能源化学(英文版)

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Preface to Special Topic: Graphene and 2D Materials for Energy Storage

Zhong-Shuai Wu, Xinhe Bao

2018, 27(1): 0-0.

摘要 ( 1559 )

Graphene,a single layer of graphite,has been one of the first real two dimensional (2D) materials isolated in 2004.Thus,graphene is becoming a cutting edge material that opens up new horizons to a whole family of 2D materials beyond the limited current applicability of graphene.The unique advantages of graphene and analogue 2D materials,such as atomic-scale thickness,high specific surface area, mechanically flexible robustness,superior storage capacity,endow them as high-performance electrodes for electrochemical energy storage devices.Although it is hard to say whether or not graphene and 2D materials will be implemented in future energy technologies,the recent achievements in this field demonstrate that their roles will be noticeable in the near future.
In view of the rapid development and great success obtained in this field,we feature this special topic of Graphene and 2D Materials for Energy Storage,publishing fundamental and applied research of the highest quality and impact covering five large aspects of graphene&2D materials for advanced energy storage systems,including but not limited to (i) controlled preparation and characterization of new-generation graphene,MXene,MoS2,metal oxide,and polymer nanosheets;(ii) elaborated assembly of new-type 1D graphene fibers,2D nanoarchitectures, and 3D porous interconnected networks;(iii) supercapacitors,micro-supercapacitors,asymmetric supercapacitors&lithium ion capacitors;(iv) Li/Na/K ion batteries,Li-S batteries and other batteries;(v) new materials,new concepts,&new device geometries,with a focus on the advanced progress of graphene and other 2D nanosheets for flexible and new-concept energy storage devices.
This topic contains 19 contributions,including 2 perspectives,10 reviews,1 communication and 6 original research articles,specifically selected from the world-leading experts working in this field of graphene and 2D materials for energy storage,because we hope they will give you new ideas.We believe that this special topic dedicated to the energy chemistry of graphene and 2D materials undoubtedly represents an insightful and comprehensive opportunity for the researchers and scientists in this field.Meanwhile,we would like to take this visible opportunity to express our sincere greeting to all the authors,reviewers,editors and publishing staffs for their great efforts and invaluable contributions for the publication of this special topic.Finally,we invite you to read the articles in this topic and see what ideas resonate with you and might be used in your future research works.

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Engineering graphene for high-performance supercapacitors: Enabling role of colloidal chemistry

Ke Zhang, Xiaowei Yang, Dan Li

2018, 27(1): 1-5. DOI: 10.1016/j.jechem.2017.11.027

摘要 ( 2045 )

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The high electrical conductivity and high specific surface area of graphene are traditionally regarded as the most intriguing features for its promise as the electrode material for supercapacitors. In this perspective, we highlight that from the engineering point of view, the unique colloidal chemistry of chemically functionalized graphene is the key property that has made graphene stand out as a promising nanoscale building block for constructing unique nanoporous electrodes for capacitive energy storage. We present several examples to demonstrate how the non-covalent colloidal forces between graphene sheets can be harnessed to engineer the nanostructure of graphene-based bulk electrodes for supercapacitors based on both the electrical double layer storage and the redox reaction or pseudo-capacitance mechanisms. The colloidal engineering strategy can be extended to enable other nanomaterials to achieve high energy storage performance.

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Graphene fiber based supercapacitors: Strategies and perspective toward high performances

Qiuyan Yang, Zhen Xu, Chao Gao

2018, 27(1): 6-11. DOI: 10.1016/j.jechem.2017.10.023

摘要 ( 1852 )

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Modern wearable electronics are thirsty for flexible, lightweight energy storage and supply devices. Flexible fiber-shaped supercapacitors, possess good flexibility, high power density, fast charging capability and long cycle life, becoming a promising option for wearable devices. The past decade has witnessed the emergence of graphene fiber based supercapacitors (GFSCs) as one of the most active vicinity in fiber-supercapactiors, for their excellent properties including high surface area, chemical stability, excellent electrical conductivity, lightweight and mechanical properties. In this perspective, we introduced the basic energy storage mechanisms of GFSCs, followed by the analysis in improving their overall performances, recent advances, and a conclusive discussion on the challenges and opportunities.

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Graphene-based materials for flexible energy storage devices

Kena Chen, Qingrong Wang, Zhiqiang Niu, Jun Chen

2018, 27(1): 12-24. DOI: 10.1016/j.jechem.2017.08.015

摘要 ( 2257 )

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The booming developments in portable and wearable electronics promote the design of flexible energy storage systems. Flexible supercapacitors and batteries as promising energy storage devices have attracted tremendous attention. As the key component of both supercapacitors and batteries, electrode materials with excellent flexibility should be considered to match with highly flexible energy storage devices. Owing to large surface area, good thermal and chemical stability, high conductivity and mechanical flexibility, graphene-based materials have been widely employed to serve as promising electrodes of flexible energy storage devices. Considerable efforts have been devoted to the fabrication of flexible graphene-based electrodes through a variety of strategies. Moreover, different configurations of energy storage devices based on these active materials are designed. This review highlights flexible graphene-based two-dimensional film and one-dimensional fiber supercapacitors and various batteries including lithium-ion, lithium-sulfur and other batteries. The challenges and promising perspectives of the graphene-based materials for flexible energy storage devices are also discussed.

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Recent advances of graphene-based materials for high-performance and new-concept supercapacitors

Xiaoyu Shi, Shuanghao Zheng, Zhong-Shuai Wu, Xinhe Bao

2018, 27(1): 25-42. DOI: 10.1016/j.jechem.2017.09.034

摘要 ( 2115 )

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Supercapacitors, with ultrahigh power density, superior rate capability, long-term cyclability, and exceptional safety, are regarded as one highly competitive candidate of electrochemical energy storage devices, filling the gap between batteries and conventional capacitors. Despite of tremendous effort, elaborated screening of high-performance electrode materials, e.g., graphene, is still intensively required. In this review, we describe the most recent progress in the research and development of graphene-based materials for high-performance and new-concept supercapacitors for the targeted applications in next-generation and smart electronics. First, the design and fabrication of high-performance supercapacitors, including electrical double layer capacitors, pseudocapacitors and hybrid supercapacitors, were summarized in term of the charge storage mechanism. Second, new-concept supercapacitors with multiple functionalities of high-voltage, fiber-shape, microscale and shape-diversity in order to fulfill the requirements of future electronics are reviewed. Accordingly, special emphasis is given to the structure-dependent-performance effects of pores, hybridization, dimensionalities of graphene-based materials on performance of supercapacitors, and tremendous potential of graphene-based planar micro-supercapacitors for the direct seamlessly integration with versatile micro-electronics. Finally, perspectives and challenges of graphene-based supercapacitors are briefly discussed.

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The roles of graphene in advanced Li-ion hybrid supercapacitors

Junwei Lang, Xu Zhang, Bao Liu, Rutao Wang, Jiangtao Chen, Xingbin Yan

2018, 27(1): 43-56. DOI: 10.1016/j.jechem.2017.11.020

摘要 ( 1990 )

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Lithium-ion hybrid supercapacitors (LIHSs), also called Li-ion capacitors, are electrochemical energy storage devices that combining the advantages of high power density of supercapacitor and high energy density of Li-ion battery. However, high power density and long cycle life are still challenges for the current LIHSs due to the imbalance of charge-storage capacity and electrode kinetics between capacitor-type cathode and battery-type anode. Therefore, great efforts have been made on designing novel cathode materials with high storage capacity and anode material with enhanced kinetic behavior for LIHSs. With unique two-dimensional form and numerous appealing properties, for the past several years, the rational designed graphene and its composites materials exhibit greatly improved electrochemical performance as cathode or anode for LIHSs. Here, we summarized and discussed the latest advances of the stateof-art graphene-based materials for LIHSs applications. The major roles of graphene are highlighted as (1) a superior active material, (2) ultrathin 2D flexible support to remedy the sluggish reaction of the metal compound anode, and (3) good 2D building blocks for constructing macroscopic 3D porous carbon/graphene hybrids. In addition, some high performance aqueous LIHSs using graphene as electrode were also summarized. Finally, the perspectives and challenges are also proposed for further development of more advanced graphene-based LIHSs.

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Recent progress in 2D materials for flexible supercapacitors

Yan Han, Yu Ge, Yunfeng Chao, Caiyun Wang, Gordon G. Wallace

2018, 27(1): 57-72. DOI: 10.1016/j.jechem.2017.10.033

摘要 ( 2331 )

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High performance supercapacitors coupled with mechanical flexibility are needed to drive flexible and wearable electronics that have anesthetic appeal and multi-functionality. Two dimensional (2D) materials have attracted attention owing to their unique physicochemical and electrochemical properties, in addition to their ability to form hetero-structures with other nanomaterials further improving mechanical and electrochemical properties. After a brief introduction of supercapacitors and 2D materials, recent progress on flexible supercapacitors using 2D materials is reviewed. Here we provide insights into the structure-property relationships of flexible electrodes, in particular free-standing films. We also present our perspectives on the development of flexible supercapacitors.

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MXene-based materials for electrochemical energy storage

Xu Zhang, Zihe Zhang, Zhen Zhou

2018, 27(1): 73-85. DOI: 10.1016/j.jechem.2017.08.004

摘要 ( 3141 )

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Rechargeable batteries and supercapacitors are widely investigated as the most important electrochemical energy storage devices nowadays due to the booming energy demand for electric vehicles and hand-held electronics. The large surface-area-to-volume ratio and internal surface areas endow two-dimensional (2D) materials with high mobility and high energy density; therefore, 2D materials are very promising candidates for Li ion batteries and supercapacitors with comprehensive investigations. In 2011, a new kind of 2D transition metal carbides, nitrides and carbonitrides, MXene, were successfully obtained from MAX phases. Since then about 20 different kinds of MXene have been prepared. Other precursors besides MAX phases and even other methods such as chemical vapor deposition (CVD) were also applied to prepare MXene, opening new doors for the preparation of new MXene. Their 2D nature and good electronic properties ensure the inherent advantages as electrode materials for electrochemical energy storage. In this review, we summarize the recent progress in the development of MXene with emphasis on the applications to electrochemical energy storage. Also, future perspective and challenges of MXene-based materials are briefly discussed regrading electrochemical energy storage.

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Two-dimensional organic cathode materials for alkali-metal-ion batteries

Chao Zhang, Chenbao Lu, Fan Zhang, Feng Qiu, Xiaodong Zhuang, Xinliang Feng

2018, 27(1): 86-98. DOI: 10.1016/j.jechem.2017.11.008

摘要 ( 2034 )

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With the increasing demand for large-scale battery systems in electric vehicles (EVs) and smart renewable energy grids, organic materials including small molecules and polymers utilized as electrodes in rechargeable batteries have received increasing attraction. In recent years, two-dimensional (2D) organic materials possessing planar layered architecture exhibit optional chemical modification, high specific surface area as well as unique electrical/magnetic properties, which have been emerging as the promising functional materials for wide applications in optoelectronics, catalysis, sensing, etc. Integrating with high-density redox-active sites and hierarchical porous structure, significant achievements in 2D organic materials as cathode materials for alkali-metal-ion batteries have been witnessed. In this review, the recent progress in synthetic approaches, structure analyses, electrochemical characterizations of 2D organic materials as well as their application in alkali-metal-ion batteries containing lithium ion battery (LIB), lithium sulfur battery (LSB), lithium air battery (LAB) and sodium ion battery (SIB) are summarized systematically, and their current challenges including cycling stability and electron conductivity for cathode materials in battery fields are also discussed.

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Two-dimensional polymer-based nanosheets for electrochemical energy storage and conversion

Shuai Bi, Chenbao Lu, Wenbei Zhang, Feng Qiu, Fan Zhang

2018, 27(1): 99-116. DOI: 10.1016/j.jechem.2017.10.026

摘要 ( 2349 )

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Over the past decades, two-dimensional (2D) nanomaterials possessing planar layered architecture and unique electronic structures have been being quickly developed, due to their wide potential application in the fields of chemistry, physics, and materials science. As a new family of 2D nanomaterials, 2D polymerbased nanosheets, featuring excellent characters, such as tunable framework structures, light weight, flexibility, high specific surface, and good semiconducting properties, have been emerging as one kind of promising functional materials for optoelectronics, gas separation, catalysis and sensing, etc. In this review, the recent progress in synthetic approach and characterization of 2D polymer-based nanosheets were summarized, and their current advances in electrochemical energy storage and conversion including second batteries, supercapacitors, oxygen reduction and hydrogen evolution were discussed systematically.

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Two-dimensional metal oxide nanosheets for rechargeable batteries

Jun Mei, Ting Liao, Ziqi Sun

2018, 27(1): 117-127. DOI: 10.1016/j.jechem.2017.10.012

摘要 ( 1788 )

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Two-dimensional (2D) metal oxide nanosheets have attracted much attention as potential electrode materials for rechargeable batteries in recent years. This is primarily due to their natural abundance, environmental compatibility, and low cost as well as good electrochemical properties. Despite the fact that most metal oxides possess low conductivity, the introduction of some conductive heterogeneous components, such as nano-carbon, carbon nanotubes (CNTs), and graphene, to form metal oxide-based hybrids, can effectively overcome this drawback. In this mini review, we will summarize the recent advances of three typical 2D metal oxide nanomaterials, namely, binary metal oxides, ternary metal oxides, and hybrid metal oxides, which are used for the electrochemical applications of next-generation rechargeable batteries, mainly for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). Hence, this review intends to functionalize as a good reference for the further research on 2D nanomaterials and the further development of energy-storage devices.

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Two-dimensional nanosheets as building blocks to construct three-dimensional structures for lithium storage

Di Zhang, Shuai Wang, Yang Ma, Shubin Yang

2018, 27(1): 128-145. DOI: 10.1016/j.jechem.2017.11.031

摘要 ( 1594 )

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2D nanosheets such as graphene, silicene, phosphorene, metal dichalcogenides and MXenes are emerging and promising for lithium storage due to their ultrathin nature and corresponding chemical/physical properties. However, the serious restacking and aggregation of the 2D nanosheets are still hampering their applications. To circumvent the issues of 2D nanosheets, one efficient strategy is to construct 3D structures with hierarchical porous structures, good chemical/mechanical stabilities and tunable electrical conductivities. In this review, we firstly focus on the available synthetic approaches of 3D structures from 2D nanosheets, and then summarize the relationships between the microstructures of 3D structures built from 2D nanosheets and their electrochemical behaviors for lithium storage. On the basis of above results, some challenges are briefly discussed in the perspective of the development of various functional 3D structures.

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Nitrogen-doped graphene: Synthesis, characterizations and energy applications

Haifeng Xu, Lianbo Ma, Zhong Jin

2018, 27(1): 146-160. DOI: 10.1016/j.jechem.2017.12.006

摘要 ( 1994 )

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Nitrogen-doped (N-doped) graphene has attracted increasing attentions because of the significantly enhanced properties in physic, chemistry, biology and material science, as compared with those of pristine graphene. By date, N-doped graphene has opened up an exciting new field in the science and technology of two-dimensional materials. From the viewpoints of chemistry and materials, this article presents an overview on the recent progress of N-doped graphene, including the typical synthesis methods, characterization techniques, and various applications in energy fields. The challenges and perspective of Ndoped graphene are also discussed. We expect that this review will provide new insights into the further development and practical applications of N-doped graphene.

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MXene-coated silk-derived carbon cloth toward flexible electrode for supercapacitor application

Minmin Hu, Tao Hu, Renfei Cheng, Jinxing Yang, Cong Cui, Chao Zhang, Xiaohui Wang

2018, 27(1): 161-166. DOI: 10.1016/j.jechem.2017.10.030

摘要 ( 2147 )

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Flexible supercapacitors are promising energy storage devices in wearable smart electronics. Exploring cost-efficient electrodes with high capacitance would promote the wide-scale application of such capacitors. Herein, in order to explore a methodology for preparing low cost, flexible, tough, and up-scalable supercapacitor electrodes, silk textile is directly carbonized to make a conductive free-standing textile substrate. Through mildly baking the surfactant-free Ti₃C₂T_x flakes suspension loaded on the carbonized silk cloth, a uniform and adhesive coating consisting of nanometer-thick Ti₃C₂T_x flakes is well established on the conductive fabric support, forming a MXene-coated flexible textile electrode. The fabricated electrode exhibits a high areal capacitance of 362 mF/cm² with excellent cyclability and flexibility. Moreover, capacitance changes neglegibly under the bending deformation mode. This study elucidates the feasibility of using silk-derived carbon cloth from biomss for MXene-based flexible supercapacitor.

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Effective exposure of nitrogen heteroatoms in 3D porous graphene framework for oxygen reduction reaction and lithium-sulfur batteries

Jia-Le Shi, Cheng Tang, Jia-Qi Huang, Wancheng Zhu, Qiang Zhang

2018, 27(1): 167-175. DOI: 10.1016/j.jechem.2017.09.014

摘要 ( 2265 )

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The introduction of nitrogen heteroatoms into carbon materials is a facile and efficient strategy to regulate their reactivities and facilitate their potential applications in energy conversion and storage. However, most of nitrogen heteroatoms are doped into the bulk phase of carbon without site selectivity, which significantly reduces the contacts of feedstocks with the active dopants in a conductive scaffold. Herein we proposed the chemical vapor deposition of a nitrogen-doped graphene skin on the 3D porous graphene framework and donated the carbon/carbon composite as surface N-doped grapheme (SNG). In contrast with routine N-doped graphene framework (NGF) with bulk distribution of N heteroatoms, the SNG renders a high surface N content of 1.81 at%, enhanced electrical conductivity of 31 S cm^-1, a large surface area of 1531 m² g^-1, a low defect density with a low I_D/I_G ratio of 1.55 calculated from Raman spectrum, and a high oxidation peak of 532.7℃ in oxygen atmosphere. The selective distribution of N heteroatoms on the surface of SNG affords the effective exposure of active sites at the interfaces of the electrode/electrolyte, so that more N heteroatoms are able to contact with oxygen feedstocks in oxygen reduction reaction or serve as polysulfide anchoring sites to retard the shuttle of polysulfides in a lithium-sulfur battery. This work opens a fresh viewpoint on the manipulation of active site distribution in a conductive scaffolds for multi-electron redox reaction based energy conversion and storage.

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Engineering two-dimensional pores in freestanding TiO₂/graphene gel film for high performance lithium ion battery

Xiaojun Yan, Yuanyuan Wang, Congcong Liu, Min Guo, Jingying Tao, Jing Cao, Dongju Fu, Liyi Dai, Xiaowei Yang

2018, 27(1): 176-182. DOI: 10.1016/j.jechem.2017.11.001

摘要 ( 1915 )

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As the key component of electrochemical energy storage devices, an electrode with superior ions transport pores is the important premise for high electrochemical performance. In this paper, we developed a unique solution process to prepare freestanding TiO₂/graphene hydrogel electrode with tunable density and porous structures. By incorporating room temperature ionic liquids (RTILs), even upon drying, the non-volatile RTILs that remained in the gel film would preserve the efficient ion transport channels and prevent the electrode from closely stacking, to develop dense yet porous structures. As a result, the dense TiO₂/graphene gel film as an electrode for lithium ion battery displayed a good gravimetric electrochemical performance and more importantly a high volumetric performance.

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Enhanced lithium storage of mesoporous vanadium dioxide(B) nanorods by reduced graphene oxide support

Thummala Jayalakshmi, Kottam Nagaraju, Ganganagappa Nagaraju

2018, 27(1): 183-189. DOI: 10.1016/j.jechem.2017.09.013

摘要 ( 1886 )

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A facile synthesis of vanadium oxide with reduced graphene oxide (rGO) is developed and used as cathode material for lithium ion batteries. VO₂(B) nanorods and VO₂(B)-rGO composite were prepared by a hydrothermal method using NaVO₃ precursor and sodium oxalate as a reducing agent. The monoclinic phase and nanorod like morphology of synthesized materials were confirmed by XRD, SEM, and TEM respectively. The electrochemical properties of samples were investigated at 1.5-4.0 V, and 0.1 C rate, and the VO₂(B) nanorods exhibit reversible capacity of about 159 mAh g^-1, whereas VO₂(B)-rGO exhibits 274 mAh g^-1. The reasonable discharge capacities were obtained at high rates. The enhanced performance in electrical energy storage system reveals the effectiveness of rGO in the composite, as it enhances the conductive electron pathway to overcome the intrinsic limits of single phase VO₂(B).

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Graphene-supported bimetal phosphorus trisulfides as novel 0D-2D nanohybrid for high rate Li-ion storage

Cheng-Feng Du, Qinghua Liang, Qingyu Yan

2018, 27(1): 190-194. DOI: 10.1016/j.jechem.2017.11.023

摘要 ( 2052 )

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Herein, we report on the synthesis and Li-ion storage properties of the 0D-2D nanohybrid consisted of bimetal phosphorus trisulfides nanoneedles (Co_0.5Ni_0.5PS₃) and graphene nanosheets (denoted as Co_0.5Ni_0.5PS₃@G). By choosing the Co_0.5Ni_0.5(OH)₂ nanoneedles as precursor, the Co_0.5Ni_0.5PS₃ derived by a simple solid-state transformation (SST) process was successfully attached onto the graphene surface. The as-prepared nanohybrids showed a superior cycling stability and rate performance for Li-ion storage. After cycling at a current density of 0.5 A g^-1 for 500 cycles, the capacity are 456 mA h g^-1. Particularly, the capacity can reach 302 mAh g^-1 at a current density of 10 A g^-1, which is 66.2% of the capacity at 0.5 A g^-1. Even cycling at a current density of 50 A g^-1, the nanocomposite can still kept a capacity of 153 mA h g^-1 with a capacity retention of 33.6%.

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Porous NiCo₂O₄ nanowires supported on carbon cloth for flexible asymmetric supercapacitor with high energy density

Huifang Zhang, Dengji Xiao, Qian Li, Yuanyuan Ma, Shuxia Yuan, Lijing Xie, Chengmeng Chen, Chunxiang Lu

2018, 27(1): 195-202. DOI: 10.1016/j.jechem.2017.10.034

摘要 ( 1951 )

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Recently, binary metal oxides have been considerably researched for energy storage since it can provide higher electrical conductivity and electrochemical activity than single components. Besides, rational arrays structure design can effectively enhance the utilization of active material. In this article, we synthesis a porous NiCo₂O₄ nanowires arrays, which were intimate contact with flexible carbon cloth (CC) by a facile hydrothermal reaction and calcination treatment. The rational array structures of NiCo₂O₄ facilitate the diffusion of electrolyte and effectively increase the utilization of active material. The asobtained NiCo₂O₄@CC electrode exhibits a high capacitance of 1183 mF cm^-2 and an outstanding capacitance retention of 90.4% after 3000 cycles. Furthermore, a flexible asymmetric supercapacitor (ASC) using NiCo₂O₄@CC as positive electrode and activated carbon cloth (ACC) as negative electrode was fabricated, which delivers a large capacitance of 750 mF cm^-2 (12.5 F cm^-3), a high energy density of 0.24 mWh cm^-2 (3.91 mWh cm^-3), as well as excellent cycle stability under different bending states. These remarkable results suggest that as-assembled NiCo₂O₄@CC//ACC ASC is a promising candidate in flexible energy storage applications.

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NS codoped carbon nanorods as anode materials for high-performance lithium and sodium ion batteries

Ajuan Hu, Song Jin, Zhenzhen Du, Hongchang Jin, Hengxing Ji

2018, 27(1): 203-208. DOI: 10.1016/j.jechem.2017.11.022

摘要 ( 1983 )

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NS codoped carbon nanorods (NS-CNRs) were prepared using crab shell as template and polyphenylene sulfide (PPS) as both the C and S precursor, followed by carbonization in NH₃. The as-obtained NS-CNRs had a diameter of~50 nm, length of several micrometers, and N and S contents of 12.5 at.% and 3.7 at.%, respectively, which can serve as anodes for both lithium-ion batteries (LIBs) and sodium ion batteries (SIBs). When serving as an anode of LIB, the NS-CNRs delivered gravimetric capacities of 2154 mAh g^-1 at current densities of 0.1 A g^-1 and 625 mAh g^-1 at current densities of 5.0 A g^-1 for 1000 cycles. When serving as an anode of SIB, the NS-CNRs delivered gravimetric capacities of 303 mAh g^-1 at current densities of 0.1 A g^-1 and 230 mAh g^-1 at current densities of 1.0 A g^-1 for 3000 cycles. The excellent electrochemical performance of NS-CNRs could be ascribed to the one-dimensional nanometer structure and high level of heteroatom doping. We expect that the obtained NS-CNRs would benefit for the future development of the doped carbon materials for lithium ion batteries and other extended applications such as supercapacitor, catalyst and hydrogen storage.

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Synthesis of bis(amino)furans from biomass based 5-hydroxymethyl furfural

Xiaoyu Wang, Wei Chen, Zheng Li, Xianhai Zeng, Xing Tang, Yong Sun, Tingzhou Lei, Lu Lin

2018, 27(1): 209-214. DOI: 10.1016/j.jechem.2017.06.015

摘要 ( 1396 )

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In this study we report a new reaction pathway in which the hydroxyl and the aldehyde groups of 5-hydroxymethyl furfural were aminated respectively. Hydroxyl group was aminated via Ritter reaction followed by direct reductive amination of aldehyde group. For the Ritter reaction of 5-hydroxymethyl furfural, mixture of trifluoromethane sulfonic acid and phosphoric anhydride showed good performance and the intermediate N-acyl-5-aminomethyl furfural with the highest yield of 89.1 wt% was obtained. Optimization of direct reductive amination of 2,5-bis(aminomethyl) furan was conducted and a yield of 45.7 wt% was achieved. This study presents a simple way for preparing bis(amino)furans from renewable biomass based 5-hydroxymethyl furfural, which enriches the biorefinery concept from biomass.

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A mixed-cation lead iodide MA_1-xEA_xPbI₃ absorber for perovskite solar cells

Yong Wang, Taiyang Zhang, Ge Li, Feng Xu, Tian Wang, Yihui Li, Yang Yang, Yixin Zhao

2018, 27(1): 215-218. DOI: 10.1016/j.jechem.2017.09.027

摘要 ( 1975 )

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The mixed-cation lead halide perovskites have emerged as a new class of promising light harvesting materials for solar cells. The formamidinium (FA), methylammonium (MA) and Cs cations are widely studied in the field of mixed-cation perovskites. Here, we have investigated ethylammonium (EA) as an alternative cation to fabricate a mixed-cation perovskite of MA_1-xEA_xPbI₃. We have characterized the materials using the X-ray diffraction (XRD), scanning electron microscope (SEM), and UV-vis spectrum. Our results have confirmed the successful incorporation of EA cations into MAPbI₃. Interestingly, the optimal amount of EA to achieve the best performance is quite low. This is different from the FA-MA mixed-cation perovskites although EA and FA have similar radii. In short, the EA-MA mixed-cation perovskite has some material and device properties highly distinguishable from the FA-MA one.

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A review on first principles based studies for improvement of cathode material of lithium ion batteries

Arslan Ullah, Abdul Majid, Naema Rani

2018, 27(1): 219-237. DOI: 10.1016/j.jechem.2017.09.007

摘要 ( 2223 )

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Lithium ion batteries (LIBs) are currently best energy storage devices providing rechargeable electrical storage to wide variety of applications-from portable electronics to automobiles. Though, these batteries are fully adopted, widely used and commercialized, but researchers are still extensively working on their constituent materials and developing technology to improve their performance. A major part of related research activities is devoted to the electrode of the battery for improvement in its performance thereby addressing issues like safety, lifetime, specific capacity, energy density and most importantly abundance and cost. There are number of cathode materials that have been proposed and tested at laboratory scale and subsequently utilized in commercialized batteries ever since the appearance of LIBs. Owing to the availability of improved computational resources in the last decade, first principles calculation has become a reliable tool and played a vital role to predict the material properties of electrodes prior to their experimental analysis. This review gives a comprehensive insight and thorough analysis of the global research efforts related to the cathode materials based on first principles framework, sheds light on current status of knowledge and explores the ways forward.

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New methyl formate synthesis method: Coal to methyl formate

Lingyun Rong, Zhongning Xu, Jing Sun, Guocong Guo

2018, 27(1): 238-242. DOI: 10.1016/j.jechem.2017.07.015

摘要 ( 1976 )

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Methyl formate is one of the most important intermediates in C1 chemistry, which has been employed in a wide range of industrial applications. Current synthesis methods for methyl formate mainly include esterification of methanol and formic acid, liquid-phase methanol carbonylation, oxidative dehydrogenation of methanol, one-step syngas synthesis, and carbon dioxide hydrogenation and condensation with methanol. Liquid-phase methanol carbonylation is currently a main commercially viable process developed by BASF Corp. for the industrial production of methyl formate. Recently, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences has developed a new synthesis method to convert coal to methyl formate (denoted as CTMF). Different from the liquid-phase methanol carbonylation using homogeneous catalysts, CTMF method features with vapor-phase methanol carbonylation using heterogeneous nanocatalysts, which can effectively utilize the coal-based syngas and produce value-added fine chemicals (i.e., methyl formate). The newly developed method not only provides a new methyl formate synthesis technology but also contributes to the development of strategies for synthesizing valuable chemicals from coal. In this review, we firstly provide introduction on the development of existing methyl formate synthesis methods and then highlight the research progress of CTMF method. Finally, a perspective on the future of CTMF is given.

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A new approach for the aerobic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid without using transition metal catalysts

Lu Zhang, Xiaolan Luo, Yebo Li

2018, 27(1): 243-249. DOI: 10.1016/j.jechem.2017.04.020

摘要 ( 1841 )

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The organic compound 2,5-furandicarboxylic acid (FDCA) has been identified by the US Department of Energy (DOE) as a valuable platform chemical for a wide range of industrial applications. Currently, the most popular route for FDCA synthesis is reported to be the oxidation of 5-hydroxymethylfurfural (HMF) by O₂ over the catalysis of noble metals (e.g., Au, Pt, Ru, and Pd). However, the high costs of noble metal catalysts remain a major barrier for producing FDCA at an industrial scale. Herein, we report a transition metal-free synthesis strategy for the oxidation of HMF to FDCA under O₂ or ambient air. A simple but unprecedented process for the aerobic oxidation of HMF was carried out in organic solvents using only bases as the promoters. According to the high performance liquid chromatography (HPLC) analysis, excellent product yield (91%) was obtained in the presence of NaOH in dimethylformamide (DMF) at room temperature (25℃). A plausible mechanism for the NaOH-promoted aerobic oxidation of HMF in DMF is also outlined in this paper. After the reaction, the sodium salt of FDCA particles were dispersed in the reaction mixture, making it possible for product separation and solvent reuse. The new HMF oxidation approach is expected to be a practical alternative to current ones, which depend on the use of noble metal catalysts.

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Improvement on electrochemical performances of nanoporous titania as anode of lithium-ion batteries through annealing of pure titanium foils

Md. Arafat Rahman, Yat Choy Wong, Guangsheng Song, De Ming Zhu, Cuie Wen

2018, 27(1): 250-263. DOI: 10.1016/j.jechem.2017.07.004

摘要 ( 1865 )

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The effect of annealing of Ti foils before anodization on the morphology and electrochemical performance of resultant nanoporous anatase TiO₂ (np-TiO₂) as anode in rechargeable lithium-ion batteries (LIBs) was investigated. The np-TiO₂ anode fabricated from annealed Ti foils exhibited higher specific surface area and reduced pore diameter compared to np-TiO₂ electrode fabricated from as-received Ti foils. The highly porous np-TiO₂ anode fabricated from annealed Ti foils exhibited 1st discharge capacity of 453.25 mAh/g and reduced to 172.70 mAh/g at 1 C current rate after 300 cycles; whilst the np-TiO₂ electrode fabricated from the as-received Ti foils exhibited 1st discharge capacity of 213.30 mAh/g and reduced to 160.0 mAh/g at 1 C current rate after 300 cycles. Even after 400 cycles, such np-TiO₂ electrode exhibited a reversible capacity of 125.0 mAh/g at 2.5 C current rate. Compared to the untreated Ti foils, the enhanced electrochemical performance of np-TiO₂ anode fabricated from annealed Ti foils was ascribed to the annealinginduced removal of residual stress among the Ti atoms. The benefit of annealing process can reduce pore size of as-fabricated np-TiO₂.

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Cu⁺-incorporated TiO₂ overlayer on Cu₂O nanowire photocathodes for enhanced photoelectrochemical conversion of CO₂ to methanol

Kangha Lee, Seokwon Lee, Hyunjin Cho, Sunil Jeong, Whi Dong Kim, Sooho Lee, Doh C. Lee

2018, 27(1): 264-270. DOI: 10.1016/j.jechem.2017.04.019

摘要 ( 1743 )

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In this paper, we report photoelectrochemical (PEC) conversion of carbon dioxide (CO₂) using photocathodes based on Cu₂O nanowires (NWs) overcoated with Cu⁺-incorporated crystalline TiO₂ (TiO₂-Cu⁺) shell. Cu₂O NW photocathodes show remanent photocurrent of 5.3% after 30 min of PEC reduction of CO₂. After coating Cu₂O with TiO₂-Cu⁺ overlayer, the remanent photocurrent is 27.6%, which is an increase by 5.2 fold. The charge transfer resistance of Cu₂O/TiO₂-Cu⁺ is 0.423 kΩ/cm², whereas Cu₂O photocathode shows resistivity of 0.781 kΩ/cm² under irradiation. Mott-Schottky analysis reveals that Cu⁺ species embedded in TiO₂ layer is responsible for enhanced adsorption of CO₂ on TiO₂ surface, as evidenced by the decrease of capacitance in the Helmholtz layer. On account of these electrochemical and electronic effects by the Cu⁺ species, the Faradaic efficiency (FE) of photocathodes reaches as high as 56.5% when TiO₂-Cu⁺ is added to Cu₂O, showing drastic increase from 23.6% by bare Cu₂O photocathodes.

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Adsorption desulfurization and weak competitive behavior from 1-hexene over cesium-exchanged Y zeolites (CsY)

Xiaojuan Liu, Dezhi Yi, Yuanyuan Cui, Li Shi, Xuan Meng

2018, 27(1): 271-277. DOI: 10.1016/j.jechem.2017.04.006

摘要 ( 1615 )

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The systematic research about the adsorption desulfurization and competitive behavior from 1-hexene over cesium-exchanged Y zeolites has been investigated. The structural properties of the adsorbents were characterized by X-ray diffraction (XRD), N₂ sorption (BET) and thermal analysis (TGA). The effects of calcination temperature, calcination atmosphere, and adsorption temperature were studied by the dynamic and static tests. The competitive adsorption mechanisms between thiophene and 1-hexene were studied by in-situ Fourier transform infrared spectroscopy (in-situ FTIR) and temperature-programmed desorption (TPD). CsY adsorbents exhibited high selectivity for thiophene even when a large amount of olefins exist. In-situ FTIR spectra of thiophene and 1-hexene adsorption indicated that both thiophene and 1-hexene were mainly adsorbed on CsY via π-complexation. The higher desorption activated energy and higher adsorption heat of thiophene than 1-hexene obtained by thiophene-TPD and hexene-TPD has revealed that thiophene is adsorbed more strongly in CsY adsorbents than 1-hexene.

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Photoelectrochemical regeneration of all vanadium redox species for construction of a solar rechargeable flow cell

Shichao Liao, Jingying Shi, Chunmei Ding, Mingyao Liu, Fengqiang Xiong, Nan Wang, Jian Chen, Can Li

2018, 27(1): 278-282. DOI: 10.1016/j.jechem.2017.04.005

摘要 ( 1689 )

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Energy storage is pivotal for the continuous utilization of solar energy suffering from the intermittency issue. Herein, we demonstrate a solar rechargeable flow cell (SRFC) based on photoelectrochemical regeneration of vanadium redox species for in-situ solar energy harvest and storage. In this device, TiO₂ and MWCNT/acetylene black (MWCNT/AB) composite are served as the photoanode and the counter electrode, respectively, with all vanadium redox couples, VO₂⁺/VO²⁺ and VO²⁺/V³⁺, as solar energy storage media. Benefitting from solar energy, the cell can be photocharged under a bias as low as 0.1 V, which is much lower than the discharge voltage of~～0.5 V. Photocharged under the optimized condition, the cell delivers a discharge energy of 23.0 mWh/L with 67.4% input electric energy savings. This prototype work may inspire the rational design for cost-effective solar energy storage devices.

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Selective hydrogenation of biomass-derived 5-hydroxymethylfurfural using palladium catalyst supported on mesoporous graphitic carbon nitride

Jiayi Chen, Yao Ge, Yuanyuan Guo, Jinzhu Chen

2018, 27(1): 283-289. DOI: 10.1016/j.jechem.2017.04.017

摘要 ( 1788 )

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Selective hydrogenation of biomass-derived 5-hydroxymethylfurfural (HMF) to 2,5-dihydroxymethyltetrahydrofuran (DHMTHF) with 96% selectivity and a complete HMF conversion is obtained over palladium catalyst supported on mesoporous graphitic carbon nitride (Pd/mpg-C₃N₄) under pressured hydrogen atmosphere in aqueous media. The excellent catalytic performance of Pd/mpg-C₃N₄ is attributed to hydrogen bonding-related competitive interactions between reactant HMF and "intermediate" 2,5-dihydroxymethylfuran (DHMF) with the support mpg-C₃N₄, which leads to a deep hydrogenation of DHMF to DHMTHF.

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Deriving Ag₃PO₄-CaO composite as a stable and solar light photocatalyst for efficient ammonia degradation from wastewater

Y. Shaveisi, S. Sharifnia

2018, 27(1): 290-299. DOI: 10.1016/j.jechem.2017.06.012

摘要 ( 1805 )

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A novel Ag₃PO₄-CaO composite photocatalyst with enhanced photocatalytic activity was synthesized and utilized for degradation of ammonia from aqueous solution under sunlight. Ag₃PO₄ was prepared by precipitation method, and the composite of Ag₃PO₄-CaO was prepared via impregnation method. Utilization of eggshell for CaO synthesis provided a cost-effective and environmental friendly way for the heterogeneous catalyst production. The as-prepared photocatalysts were characterized by FT-IR, FE-SEM, TEM, EDX, UV-vis and PL. Results show that the Ag₃PO₄-CaO samples have excellent photocatalytic performances in the wide visible-light region. The effect of operating parameters like the content of Ag₃PO₄ in composite, initial ammonia concentration, pH of solution, catalyst dosage and oxygen supply was investigated. The photocatalyst with 60 wt% content of Ag₃PO₄ had a high photocatalytic performance, because a low content of Ag₃PO₄ causes weak light absorption, and the excess amount of it results in serious electron-hole recombination due to the aggregation of Ag₃PO₄ particles. The maximum ammonia degradation (about 70%) was achieved in 340 mg/L of ammonia, pH 11, and 1.25 g/L of catalyst in the presence of pure oxygen. In comparison to Ag₃PO₄, 60 wt% Ag₃PO₄-CaO had a good stability and it could have been easily separated from the solution for recycling.

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Metal organic framework-combustion: A one-pot strategy to NiO nanoparticles with excellent anode properties for lithium ion batteries

Vaiyapuri Soundharrajan, Balaji Sambandam, Jinju Song, Sungjin Kim, Jeonggeun Jo, Pham Tung Duong, Seokhun Kim, Vinod Mathew, Jaekook Kim

2018, 27(1): 300-305. DOI: 10.1016/j.jechem.2017.05.003

摘要 ( 1971 )

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NiO nanoparticles with average particles size of 30 nm are synthesized using a one-pot metal-organic framework-combustion (MOF-C) technique, for use as an anode material in rechargeable lithium ion batteries (LIBs). The structural and electronic properties of these nanoparticles are studied using various techniques, including powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and N₂ adsorption/desorption studies. The as-synthesized NiO nanoparticles sustained reversible stable capacities of 748 and 410 mAh/g at applied current densities of 500 and 1000 mA/g, respectively, after 100 cycles. Furthermore, the anode displays a notable rate capability, achieving a stable capacity of~200 mAh/g at a high current density of 10 A/g. These results indicate that the size of the NiO nanoparticles and their high surface area influence their electrochemical properties. Specifically, this combustion strategy is clearly favorable for improving the cyclability and rate capability of various metal oxides in rechargeable battery electrodes.

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Graphene quantum dots decorated rutile TiO₂ nanoflowers for water splitting application

A. Bayat, E. Saievar-Iranizad

2018, 27(1): 306-310. DOI: 10.1016/j.jechem.2017.09.036

摘要 ( 1717 )

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Flower like rutile TiO₂ films were decorated with green-photoluminescent graphene quantum dots (GQDs) and photovoltaic properties were investigated for water splitting application. Rutile TiO₂ nanoflowers (NFs) and GQDs (average width of~12 nm) synthesized separately using a hydrothermal method and TiO₂ NFs were decorated with various amounts of GQDs solution (x=5, 10, 15 and 20 μL) by spin coating. Optical characterization reveals that GQDs are highly luminescent and absorb UV and visible light photons with wavelengths up to 700 nm. GQD_s-x/TiO₂ electrode shows a photocurrent enhancement of~95% compared to pristine TiO₂ NFs for the optimum sample (x=15 μL) at an applied potential of P=0 V using 1 M Na₂SO₄ solution as electrolyte.

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A comparative study on different regeneration processes of Pt-Sn/γ -Al₂O₃ catalysts for propane dehydrogenation

Changyong Sun, Junyin Luo, Mingjin Cao, Ping Zheng, Guocheng Li, Jiahao Bu, Zhou Cao, Shihong Chen, Xiaowei Xie

2018, 27(1): 311-318. DOI: 10.1016/j.jechem.2017.09.035

摘要 ( 1853 )

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Three different regeneration processes including hydrogen or nitrogen purging and coke-burning treatment were used to restore the Pt-Sn/γ -Al₂O₃ catalysts, through which propane dehydrogenation reaction was performed in a consecutive reaction-regeneration mode. It was found that the catalyst using hydrogen regeneration showed the best stability compared with those regenerated by nitrogen purging and coke-burning treatment, suggesting that hydrogen regeneration is an effective approach for maintaining the performance of Pt-Sn/γ -Al₂O₃ catalysts in propane dehydrogenation reaction. The effect of different regeneration atmospheres on the metal active center and the coke deposition was investigated by XRD, TEM, N₂-physisorption, TPO, TG and Raman technologies, and the results revealed that hydrogen or nitrogen regeneration resulted in little impact on the size and structure of metal active center, retaining the effective PtSn phase over the catalyst. Moreover, hydrogen regeneration not only removed the low dense components of the coke, but also altered the property of the residual coke through hydrogenation, leading to a higher mobility of coke, and thus a higher accessibility of the metal active centers. Whereas nitrogen regeneration only removed the low dense components of the coke. Although coke-burning regeneration caused a thorough coke removal, the catalyst subjected to repeated redox exhibited poor stability due to metal agglomeration, phase segregation and the resulting large Pt₃Sn particle and core-shell structure with a Sn-rich surface.

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Higher alcohols synthesis from syngas over lanthanum-promoted CuZnAl catalyst

Xuan Deng, Yong-Jun Liu, Wei Huang

2018, 27(1): 319-325. DOI: 10.1016/j.jechem.2017.10.007

摘要 ( 1920 )

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CuZnAl catalysts with different La loadings were prepared by a complete liquid phase method and tested for higher alcohols (C₂₊OH) synthesis from syngas at the conditions of 250-290℃, 4.5 MPa, feed low rate=150 mL/min and H₂/CO=2. The catalysts were characterized by XRD, H₂-TPR, NH₃-TPD, N₂ adsorption, XPS, and TEM techniques. Characterization results showed that the incorporation of La into CuZnAl catalysts resulted in the decrease of crystallite size of Cu⁰ and a strong interaction among copper and zinc or aluminum oxides. Especially, the incorporation of La increased the amount of weak acid and the Cu content on catalyst surface, which was speculated to contribute the formation of higher alcohols. Among these La-promoted CuZnAl catalysts, the La0.1 catalyst exhibited the best catalytic performance and the selectivity to higher alcohols reached above 60% when the reaction temperature was 290℃.

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Study on durability of Pt supported on graphitized carbon under simulated start-up/shut-down conditions for polymer electrolyte membrane fuel cells

Won Suk Jung

2018, 27(1): 326-334. DOI: 10.1016/j.jechem.2017.05.012

摘要 ( 1827 )

The primary issue for the commercialization of proton exchange membrane fuel cell (PEMFC) is the carbon corrosion of support under start-up/shut-down conditions. In this study, we employ the nanostructured graphitized carbon induced by heat-treatment. The degree of graphitization starts to increase between 900 and 1300℃ as evidenced by the change of specific surface area, interlayer spacing, and I_D/I_G value. Pt nanoparticles are deposited on fresh carbon black (Pt/CB) and carbon heat-treated at 1700℃ (Pt/HCB17) with similar particle size and distribution. Electrochemical characterization demonstrates that the Pt/HCB17 shows higher activity than the Pt/CB due to the inefficient microporous structure of amorphous carbon for the oxygen reduction reaction. An accelerating potential cycle between 1.0 and 1.5 V for the carbon corrosion is applied to examine durability at a single cell under the practical start-up/shutdown conditions. The Pt/HCB17 catalyst shows remarkable durability after 3000 potential cycles. The Pt/HCB17 catalyst exhibits a peak power density gain of 3%, while the Pt/CB catalyst shows 65% loss of the initial peak power density. As well, electrochemical surface area and mass activity of Pt/HCB17 catalyst are even more stable than those of the Pt/CB catalyst. Consequently, the high degree of graphitization is essential for the durability of fuel cells in practical start-up/shut-down conditions due to enhancing the strong interaction of Pt and π-bonds in graphitized carbon.

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