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2018, Vol. 27, No. 3　Online: 2018-05-15


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Halide perovskite nanocrystals: Synthesis, properties and applications

This review summarized the recent developments in the field of halide perovskite nanocrystals (NCs) and their derivatives. The synthetic methods of these perovskite NCs, as well as their optical properties, structural modification and applications have been discussed. Despite the significant progress achieved in perovskite nanostructures, challenges regarding to their long-term stability, inferior charger transport features, and lead-content still need to be addressed. Proper surface modification is a possible approach to obtain NCs with both excellent conductivity and stability. Besides, more practical works need to be done to explore environmentally benign lead-free NCs, with excellent electronic properties.

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Review

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Three dimensional photovoltaic fibers for wearable energy harvesting and conversion Ming Peng, Bin Dong, Dechun Zou 2018, 27(3): 611-621.  DOI: 10.1016/j.jechem.2018.01.008 摘要 ( 1460 )   As the development of smart electronics, self-powered sources have been attracting increasing attention. This review summarizes research progress of photovoltaic fibers and their integrated power sources with multi-stage energy conversion. Recent development of three dimensional photovoltaic fibers is glanced with special attention to structure design and materials of typical photovoltaic types (inorganic, organic, dye/quantum dot sensitized and perovskite solar cells). The application of carbon materials in fiber energy is focused as it is a hot topic recently. The hybrid energy systems based on fiber solar cells and fiber supercapacitors, fiber batteries and fiber nanogenerators are summarized together with hybrid energy textiles. This review provides a macroscopic view of novel energy fibers and will attract research interest in flexible/wearable fiber electronics and energy textiles.

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Nanocrystals of halide perovskite: Synthesis, properties, and applications Chi Yang, Yihui Wu, Qingshan Ma, Wen-Hua Zhang 2018, 27(3): 622-636.  DOI: 10.1016/j.jechem.2017.12.007 摘要 ( 2234 )   Recently, halide perovskite materials have become an exciting topic of research mainly due to their outstanding photovoltaic performance with the highest efficiency up to 22.1% at present. The nanocrystals (NCs) of these perovskites show quantum size effect, tunable bandgap, and excellent photoluminescence quantum yield (PLQY) in specific cases. Perovskite NCs have hence displayed great potentials in a broad range of applications, such as solar cells, light-emitting devices (LEDs), photodetectors, and lasers. In this review, we summarized the recent progress on the synthesis, optoelectronic properties and applications of the nanostructures of these halide perovskite materials, including hybrid organic-inorganic perovskites, pure inorganic perovskite, and perovskite-derived NCs. We have also provided a critical outlook into the challenges ahead.

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Recent theoretical progress in the development of perovskite photovoltaic materials Xin Zhou, Joanna Jankowska, Hao Dong, Oleg V. Prezhdo 2018, 27(3): 637-649.  DOI: 10.1016/j.jechem.2017.10.010 摘要 ( 1749 )   Since the seminal work by Kojima et al. in 2009, solar cells based on hybrid organic-inorganic perovskites have attracted considerable attention and experienced an exponential growth, with photovoltaic efficiencies as of today reaching above 22%. Despite such an impressive development, some key scientific issues of these materials, including the presence of toxic lead, the poor long-term device stability under heat and humidity conditions, and the anomalous hysteresis of the current-voltage curves shown by various solar cell devices, still remain unsolved and constitute an important focus of experimental and theoretical researchers throughout the world. Density functional theory calculations have been successfully applied to exploring structural and electronic properties of semiconductors, complementing the experimental results in search and discovery of novel functional materials. In this review, we summarize the current progress in perovskite photovoltaic materials from a theoretical perspective. We discuss design of lead-free perovskite materials, humidity-induced degradation mechanisms and possible origins for the observed solar cell hysteresis, and assess future research directions for advanced perovskite solar cells based on computational materials design and theoretical understanding of intrinsic properties.

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Progress in hole-transporting materials for perovskite solar cells Xichuan Yang, Haoxin Wang, Bin Cai, Ze Yu, Licheng Sun 2018, 27(3): 650-672.  DOI: 10.1016/j.jechem.2017.12.017 摘要 ( 1481 )   In recent years the photovoltaic community has witnessed the unprecedented development of perovskite solar cells (PSCs) as they have taken the lead in emergent photovoltaic technologies. The power conversion efficiency of this new class of solar cells has been increased to a point where they are beginning to compete with more established technologies. Although PSCs have evolved a variety of structures, the use of hole-transporting materials (HTMs) remains indispensable. Here, an overview of the various types of available HTMs is presented. This includes organic and inorganic HTMs and is presented alongside recent progress in associated aspects of PSCs, including device architectures and fabrication techniques to produce high-quality perovskite films. The structure, electrochemistry, and physical properties of a variety of HTMs are discussed, highlighting considerations for those designing new HTMs. Finally, an outlook is presented to provide more concrete direction for the development and optimization of HTMs for highefficiency PSCs.

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Recent advances of flexible perovskite solar cells Lingbo Li, Shasha Zhang, Zhichun Yang, Engamba Esso Samy Berthold, Wei Chen 2018, 27(3): 673-689.  DOI: 10.1016/j.jechem.2018.01.003 摘要 ( 1963 )   In few years only, the efficiency record of perovskite solar cells (PSCs) has raised quickly from 3.8% to over 22%. This emerging photovoltaic technology has primarily shown its great potential of industrialization. Flexible PSCs are thought to be one of the most priority options for mass production, related to the intrinsic advantage of perovskite thin films which could be deposited by facile solution processes at low temperature. Flexible PSCs have at least four advantages in comparison to the rigid counterpart:(1) it can generate higher power output at lighter weight, (2) it is easily portable, (3) it can be easily attached to architectures or textiles with diverse shapes, and (4) it is compatible with roll-to-roll fabrication in a large scale. In this review, we have summarized recent development of the key materials and technologies applied in flexible PSCs. The key materials including flexible substrates, transparent and conductive electrodes, and interfacial materials; some key technologies about roll-to-roll manufacture, encapsulation technology have been overviewed. Finally, a prospect on possible application directions of flexible PSCs has been discussed.

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Layered-stacking of titania films for solar energy conversion: Toward tailored optical, electronic and photovoltaic performance Wu-Qiang Wu, Jin-Feng Liao, Dai-Bin Kuang 2018, 27(3): 690-702.  DOI: 10.1016/j.jechem.2017.11.030 摘要 ( 1258 )   Nanostructured TiO2 with differentiate morphologies has attracted tremendous attention due to its wide band-gap nature as well as outstanding optical and electric properties for solar-driven light-toelectricity conversion application. Layered-stacking TiO2 film such as double-layer, tri-layer, quadrupleor quintuplicate-layer, is highly desirable to the design of high-performance semiconductor material photoanodes and the development of advanced photovoltaic devices. In this minireview, we will summarize the recent progress and achievements on proof-of-concept of layered-stacking TiO2 films (LTFs) for solar cells with emphasis on the tailored properties and synergistic functionalization of LTFs, such as optimized sensitizer adsorption, broadened light confinement as well as facilitated electron transport characteristics. Various demonstrations of LTFs photovoltaic systems provide lots of possibilities and flexibilities for more efficient solar energy utilization that a wide variety of TiO2 with distinguished morphologies can be integrated into differently structured photoanodes with synergistic and complementary advantages. This key structure engineering technology will also pave the way for the development of next generation state-ofthe-art electronics and optoelectronics. Finally, from our point of view, we conclude the future research interest and efforts for constructing more efficient LTFs as photoelectrode, which will be highly warranted to advance the solar energy conversion process.

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Review on transition metal compounds based counter electrode for dye-sensitized solar cells Chenjing Gao, Qianji Han, Mingxing Wu 2018, 27(3): 703-712.  DOI: 10.1016/j.jechem.2017.09.003 摘要 ( 1726 )   Commercial application of the dye-sensitized solar cells (DSCs) depends on great improvement of the power conversion efficiency and reduction of the fabrication cost. Generally, developing low cost counter electrode catalysts to replace the expensive Pt counter electrode is a feasible path to reduce the production cost of DSCs. In this review article, we summarize the recent progress on the transition metal compound based counter electrode catalysts containing carbides, nitrides, oxides, sulfides, phosphide, selenides, borides, silicide, and telluride toward the regeneration of the traditional iodide redox couple. Moreover, the benefits and drawbacks of each kind of CE catalyst are discussed and the research directions to design new counter electrode catalysts in future research are also proposed.

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Development of antimony sulfide-selenide Sb2(S, Se)3-based solar cells Xiaomin Wang, Rongfeng Tang, Chunyan Wu, Changfei Zhu, Tao Chen 2018, 27(3): 713-721.  DOI: 10.1016/j.jechem.2017.09.031 摘要 ( 1491 )   Antimony sulfide-selenide Sb2(S, Se)3, including Sb2S3 and Sb2Se3, can be regarded as binary metal chalcogenides semiconductors since Sb2S3 and Sb2Se3 are isomorphous. They possess abundant elemental storage, nontoxicity, good stability with regard to moisture at elevated temperatures and suitable physical parameters for light absorption materials in solar cells. To date, quite a few attempts have been conducted in the materials synthesis, photovoltaic property investigation and device fabrication. Benefiting from previous investigation in thin film solar cells and new generation nanostructured solar cells, this class of materials has been applied in either sensitized-architecture or planar heterojunction solar cells. Decent power conversion efficiencies from 5% to 7.5% have been achieved. Apparently, further improvement on the efficiency is required for future practical applications. To give an overview of this research field, this paper displays some typical researches regarding the methodologies toward the antimony sulfide-selenide synthesis, development of interfacial materials and device fabrications, during which we highlight some critical findings that promote the efficiency enhancement. Finally, this paper proposes some outstanding issue regarding fundamental understanding of the materials, some viewpoints for the efficiency improvement and their future challenges in solar cell applications.

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High-quality perovskite MAPbI3 single crystals for broad-spectrum and rapid response integrate photodetector Yunxia Zhang, Yucheng Liu, Zhou Yang, Shengzhong (Frank) Liu 2018, 27(3): 722-727.  DOI: 10.1016/j.jechem.2017.11.002 摘要 ( 1689 )   Organic-inorganic single-crystalline perovskites have attracted significant attentions due to their exceptional progress in intrinsic properties' investigation and applications in photovoltaics and optoelectronics. In this study, the large perovskite CH3NH3PbI3 single crystal with the largest length of 80 mm was prepared through the method of inverse-temperature crystallization. Meanwhile, the mass production of integrate photodetectors have been fabricated on the single-crystalline wafer and the photoresponse performances were investigated. The results show that the single-crystalline photodetectors have broad spectrum response to 900 nm, rapid response speed (<40 μs) and excellent stability. These findings are of great importance for future promising perovskite single crystalline for integrated photoelectronic application.

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Effects of anchoring groups on perylenemonoimide-based sensitizers for p-type dye-sensitized solar cells and photoelectrochemical cells Kang Yun, Shicong Zhang, Fengtao Yu, Haonan Ye, Jianli Hua 2018, 27(3): 728-735.  DOI: 10.1016/j.jechem.2018.02.008 摘要 ( 1444 )   In this work, two new dyes YK-1 and YK-2 with carboxylic acid and hydroxamic acid as anchoring groups, respectively, in combination with diphenylamine as donor and perylenemonoimide as acceptor were synthesized and applied in p-type dye-sensitized solar cells (p-DSCs) and dye-sensitized photoelectrochemical cells (PEC). The results showed that the sensitizer (YK-1) based on carboxylic acid displayed a higher conversion efficiency of 0.064% under AM 1.5 solar conditions in p-DSCs. However, it was interesting that the hydroxamic acid based sensitizer (YK-2) on NiO photocathode displayed better performance in a hydrophilic environment over a broad pH range under visible-light irradiation because of a versatile covalent attachment to NiO surfaces. This may be ascribed to hydroxamic acid anchors, which have more sites interacting with the surface of NiO in aqueous solution. This study demonstrates that YK-2 containing hydroxamic acid anchoring group is a promising candidate to achieve highly efficient and stable activity for dye-sensitized PEC system.

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ZnSe quantum dots downshifting layer for perovskite solar cells Bei Wang, Bo Li, Ting Shen, Mengjie Li, Jianjun Tian 2018, 27(3): 736-741.  DOI: 10.1016/j.jechem.2017.11.021 摘要 ( 1608 )   To date, the instability of organometal halide perovskite solar cells (PSCs) has become the focus issue that limits the development and long-term application of PSCs. Both the ultraviolet (UV) rays in sunlight and moisture in air can significantly accelerate the disintegration of the perovskite. Here, we introduced a ZnSe quantum dots layer as downshifting materials, which was spin-coated onto the backside of PSCs. This layer converted the UV rays into visible light to prevent the destruction of PSCs as well as increase the light harvesting of the perovskite layer. Under the UV irradiation in the moisture ambient (40%), the destruction speed of the unencapsulated perovskite films were also delayed evidently. In addition, the power conversion efficiency (PCE) of the PSCs was increased from 16.6% to 17.3% due to the increase of the visible light absorbance of the perovskite.

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Bifunctional polyaniline electrode tailored hybridized solar cells for energy harvesting from sun and rain Jialong Duan, Yanyan Duan, Yuanyuan Zhao, Yingli Wang, Qunwei Tang, Benlin He 2018, 27(3): 742-747.  DOI: 10.1016/j.jechem.2017.10.017 摘要 ( 1433 )   Pursuit of energy-harvesting or -storage materials to realize outstanding electricity output from nature has been regarded as a promising strategy to resolve the energy-lack issue in the future. Among them, the solar cell as a solar-to-electrical conversion device has been attracted enormous interest to improve the efficiency. However, the ability to generate electricity is highly dependent on the weather conditions, in other words, there is nearly zero power output in dark-light conditions, such as rainy, cloudy, and night, lowering the monolithic power generation capacity. Here, we present a bifunctional polyaniline film via chemical bath deposition, which can harvest energy from the rain, yielding an induced current of 2.57 μA and voltage of 65.5 μV under the stimulus of real raindrop. When incorporating the functional PANi film into the traditional dye sensitized solar cell as a counter electrode, the hybridized photovoltaic can experimentally realize the enhanced output power via harvesting energy from rainy and sunny days. The current work may show a new path for development of advanced solar cells in the future.

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Interfacial charge-transfer engineering by ionic liquid for high performance planar CH3NH3PbBr3 solar cells Xiaojia Zheng, Wei Yu, Shashank Priya 2018, 27(3): 748-752.  DOI: 10.1016/j.jechem.2017.09.016 摘要 ( 1977 )   The energy barrier at the CH3NH3PbBr3/TiO2 interface hinders the electron transfer from CH3NH3PbBr3 to compact TiO2 (cp-TiO2). Ionic liquid (IL), that forms dipoles pointing away from TiO2, can adjust the work function of TiO2 resulting in suitable energy level for charge transfer from CH3NH3PbBr3 to TiO2. The time-resolved photoluminescence spectroscopy (TRPL) measurements confirm faster electron transfer from the CH3NH3PbBr3 film to TiO2 after modification by IL. Solar cells based on IL modified cp-TiO2 demonstrate efficiency of ~6%, much higher than the devices (0.2%) fabricated using untreated cp-TiO2 as the electron transport layer.

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Deep insights into the advancements and applications of perovskite based photovoltaic cells Chandni Devi, Rajesh Mehra 2018, 27(3): 753-763.  DOI: 10.1016/j.jechem.2017.12.008 摘要 ( 1176 )   The organometal halide perovskite materials have a blend of surprising optoelectronic properties, for example high value of absorption coefficient and abrupt optical retention edge, lifetime, long charge carrier diffusion length and many more. Brought in conjunction with the capacity for manufacturing at low temperature, likewise from the solution, devices based on perovskite, particularly solar cells have been contemplated seriously with striking advancements in performance, in the course of recent years. The amalgamation of minimal effort, high efficiency and extra applications gives incredible potential to commercialization of these cells. The applications and performance of perovskite cells frequently relate with the structures of the device. Numerous creative structures of the devices were produced, targeting for vast scale manufacture, diminishing creation cost, upgrading the PCE and subsequently expanding the prospective for future applications. This paper outlines the various advanced structures of PSC, challenges confronted by these PSCs and their future perspectives. The commercial applications of PSC are additionally talked about in this paper.

Communication

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Printed hole-conductor-free mesoscopic perovskite solar cells with excellent long-term stability using PEAI as an additive Cong Xu, Zheling Zhang, Yue Hu, Yusong Sheng, Pei Jiang, Hongwei Han, Jian Zhang 2018, 27(3): 764-768.  DOI: 10.1016/j.jechem.2018.01.030 摘要 ( 1611 )   Phenethylamine (PEA) was successfully introduced into hole-conductor-free, fully printable mesoscopic MAPbI3 perovskite solar cells (MPSCs) with a carbon electrode by mixing phenethylammonium iodide with MAPbI3 perovskite solution. PEA-MAPbI3 films show better pore filling into TiO2 scaffold that forms better contact, and induce longer exciton lifetime and higher quantum efficiency of photoinduced charge separation. As a result, the power conversion efficiency of PEA-MAPbI3 MPSCs is 37% higher than that of MAPbI3 MPSCs. And PEA-MAPbI3 MPSCs show excellent long-term stability that could keep 90% of origin power conversion efficiency for over 80 days in the air.

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Dehydration of fructose and glucose to 5-hydroxymethylfurfural over Al-KCC-1 silica Fereshte Shahangi, Alireza Najafi Chermahini, Mohammad Saraji 2018, 27(3): 769-780.  DOI: 10.1016/j.jechem.2017.06.004 摘要 ( 1236 )   In this research, the influence of several factors such as reaction time, catalyst weight, temperature and different solvents on dehydration reaction of fructose and glucose to 5-hydroxymethylfurfural (HMF) was surveyed. Nanosphere Al-KCC-1 silica with fibrous morphology was manufactured and used as proficient and recyclable catalyst for this reaction. SEM, TEM, BET, XRD, EDX, elemental mapping, ICP and FT-IR spectroscopy methods were applied for characterization of the Al-KCC-1 (molar ratio Si/Al=5, 40) catalysts. 162℃ and 1 h are the best conditions for the fructose dehydration. Under this situation HMF yield and selectivity are 92.9% and 94.5% respectively and fructose conversion is 98.4%. Also 170℃ and 2 h are the best conditions for the glucose dehydration. In this situation HMF yield and selectivity are 39.0% and 39.9% respectively and glucose conversion is 97.8%.

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Enhanced gas separation performance of mixed matrix hollow fiber membranes containing post-functionalized S-MIL-53 Haitao Zhu, Xingming Jie, Lina Wang, Guodong Kang, Dandan Liu, Yiming Cao 2018, 27(3): 781-790.  DOI: 10.1016/j.jechem.2017.04.016 摘要 ( 1329 )   Mixed matrix hollow fiber membranes (MMHFMs) filled with metal-organic frameworks (MOFs) have great potential for energy-efficient gas separation processes, but the major hurdle is polymer/MOFs interfacial defects and membrane plasticization. Herein, lab-synthesized MIL-53 was post-functionalized by aminosilane grafting and subsequently incorporated into Ultem®1000 polymer matrix to fabricate high performance MMHFMs. SEM, DLS, XRD and TGA were performed to characterize silane-modified MIL-53 (S-MIL-53) and prepared MMHFMs. Moreover, the effect of MOFs loading was systematically investigated first; then gas separation performance of MMHFMs for pure and mixed gas was evaluated under different pressures. MMHFMs containing post-functionalized S-MIL-53 achieved remarkable gas permeation properties which was better than model predictions. Compared to pure HFMs, CO2 permeance of MMHFM loaded with 15% S-MIL-53 increased by 157% accompanying with 40% increase for CO2/N2 selectivity, which outperformed the MMHFM filled with naked MIL-53. The pure and mixed gas permeation measurements with elevated feed pressure indicated that incorporation of S-MIL-53 also increased the resistance against CO2 plasticization. This work reveals that post-modified MOFs embedded in MMHFMs facilitate the improvement of gas separation performance and suppression of membrane plasticization.

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Vertically aligned NiS nano-flakes derived from hydrothermally prepared Ni(OH)2 for high performance supercapacitor A. M. Patil, A. C. Lokhande, P. A. Shinde, J. H. Kim, C. D. Lokhande 2018, 27(3): 791-800.  DOI: 10.1016/j.jechem.2017.05.005 摘要 ( 1467 )   In present work, the vertically aligned NiS nano-flakes composed thin film is prepared by anionic exchange process in which hydrothermally prepared Ni(OH)2 is used as a parent thin film and Na2S as a sulfide ion source. This synthesis process produced fully transformed and shape-controlled nano-flakes of NiS from nano-flowers of Ni(OH)2. The electrochemical supercapacitor properties of NiS electrode are studied with cyclic voltammetry (CV), galvonostatic charge discharge (GCD) and electrochemical impedance spectroscopy (EIS) techniques. Highly porous surface area (85 m2/g) of NiS nano-flakes makes large material contribution in electrochemical reaction stretching specific capacitance (Cs) of 880 F/g at scan rate of 5 mV/s and 90% electrochemical stability up to 4000 CV cycles in 2 M KOH electrolyte. Further, the flexible solid-state symmetric supercapacitor device (NiS/PVA-LiClO4/NiS) has been fabricated using NiS electrodes with polyvinyl alcohol (PVA)-lithium perchlorate (LiClO4) gel electrolyte. The NiS/PVA-LiClO4/NiS device exhibits specific capacitance of 56 F/g with specific energy of 14.98 Wh/kg and excellent cycling stability after 2000 cycles. In addition, the NiS/PVA-LiClO4/NiS device demonstrates illumination of red light emitting diode (LED) for 60 s, which confirms the practical applicability of NiS/PVA-LiClO4/NiS device in energy storage.

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Oxidative depolymerization of lignin improved by enzymolysis pretreatment with laccase Yuan Zhu, Xinping Ouyang, Ying Zhao, Linfeng Jiang, Haijun Guo, Xueqing Qiu 2018, 27(3): 801-805.  DOI: 10.1016/j.jechem.2017.04.018 摘要 ( 1409 )   A new lignin depolymerization approach for improving the yield of aromatic monomers (YAM) by enzymolysis pretreatment was investigated, in which lignin was pretreated with laccase followed by oxidative depolymerization. It was found that lignin depolymeirzation was enhanced significantly by enzymolysis. The oxidative depolymerization contributed to 21.37% of YAM after the enzymolysis pretreatment, whereas the conventional oxidative depolymerization only gave 14.10% of YAM. The addition of ethanol in enzymatic pretreatment process improved the efficiency of enzymolysis, which effectively improved the solubility of pretreated lignin and depolymerization degree (DD) of lignin. The enzymolysis pretreatment increased the content of syringyl (S) style aromatic monomers, which hindered the recondensation among polymerized products. As lignin has low solubility in acidic aqueous solution, ethanol was added into enzymolysis system to improve the efficiency. However, the enzymolysis of lignin should be carried out for a limited period of time to prevent the inactivation of laccase.

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Ionic liquid-assisted hydrothermal synthesis of SnS nanoparticles: Electrode materials for lithium batteries, photoluminescence and photocatalytic activities K. N. Manukumar, G. Nagaraju, Brij Kishore, C. Madhu, N. Munichandraiah 2018, 27(3): 806-812.  DOI: 10.1016/j.jechem.2017.05.010 摘要 ( 1597 )   Tin mono-sulphide (SnS) nanoparticles (Nps) have been successfully synthesised through ionic liquid assisted hydrothermal method using hydrated tin (Ⅱ) chloride as a precursor, thiourea as sulphur source precursors using 2-Methoxy ethyl methyl imidazolium methane sulfonate ionic liquid as co-solvent. The Reitveld refinement on powder X-ray diffraction (PXRD) confirmed the presence of orthorhombic SnS structure as major phase along with traces amount of SnS2 and Sn2S3. Diffuse reflectance spectrum studies revealed the energy band gap around 1.38 eV. TEM images confirmed the SnS Nps with average particle size of 40 nm and HRTEM suggest good crystallinity. The electrochemical property for lithium storage behaviour shows an initial discharge capacity of 658 mAh/g and it retains discharge capacity of 426 mAh/g for 16 cycles, at current density 100 mA/g. The obtained results indicate that SnS Nps to be one of the possible promising anode materials for next generation Lithium batteries. Photoluminescence study of SnS Nps shows a strong green emission at 530 nm. SnS Nps were also tested for the photocatalytic adsorption of methylene blue and Rhodamine B.

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A polypyrrole-coated acetylene black/sulfur composite cathode material for lithium-sulfur batteries Wu Yang, Wang Yang, Jiani Feng, Xiujuan Qin 2018, 27(3): 813-819.  DOI: 10.1016/j.jechem.2017.05.007 摘要 ( 1387 )   Lithium-sulfur batteries are promising next-generation energy storage devices beyond conventional lithium ion batteries. However, it suffers from rapid capacity fading and poor cyclic stability. Here we report a facile in situ sulfur deposition and chemical oxidative polymerization method for preparing acetylene black/sulfur@polypyrrole (AB/S@PPy) composite as a cathode material for lithium-sulfur batteries. It is demonstrated that PPy is covered uniformly onto the surface of the AB/S composite forming a core-shell structure. In the structure, AB in the matrix and PPy on the surface acts as a combined conductive framework to provide ions and electrons transport pathways, and to inhibit the dissolution or diffusion of polysulfide into the electrolyte. The as-designed AB/S@PPy composite exhibits excellent rate capability and cyclic stability. The initial discharge specific capacity is as high as 1179.4 mAh/g, and remains at 769.3 mAh/g after 80 cycles at 0.2 C. Even at a high rate (0.5 C), a maximum discharge capacity of 811.1 mAh/g is still achieved for the AB/S@PPy composite after activation, and the capacity retention is over 62.5% after 200 cycles.

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Modified silicon carbide whisker reinforced polybenzimidazole used for high temperature proton exchange membrane Yangben Cai, Zhouying Yue, Qianlu Jiang, Shiai Xu 2018, 27(3): 820-825.  DOI: 10.1016/j.jechem.2017.05.002 摘要 ( 1480 )   Polybenzimidazole containing ether bond (OPBI) was reinforced with silicon carbide whisker (mSiC) modified by 3-aminopropyltriethoxysilane (KH550), and then doped with phosphoric acid (PA) to obtain OPBI/mSiC/PA membranes. These OPBI/mSiC/PA membranes have excellent mechanical strength and oxidative stability and can be used for high temperature proton exchange membrane (HT-PEM). The tensile strength of OPBI/mSiC/PA membranes ranges from 27.3 to 36.8 MPa, and it increases at first and then decreases with the increase of mSiC content. The high mSiC content and PA doping level contribute to improving the proton conductivity of membranes. The proton conductivity of PBI/mSiC-10/PA membrane is 27.1 mS cm-1 at 170℃ without humidity, with an increase of 55.7% compared with that of OPBI/PA membrane. These excellent properties make OPBI/mSiC/PA membranes promising membrane materials for HT-PEM applications.

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Ultrasonic-assisted synthesis of plasmonic Z-scheme Ag/AgCl/WO3-nanoflakes photocatalyst in geothermal water with enhanced visible-light photocatalytic performance Qingyong Li, Guorong Duan, Jie Luo, Xiaoheng Liu 2018, 27(3): 826-835.  DOI: 10.1016/j.jechem.2017.05.011 摘要 ( 1314 )   In this study, the Ag/AgCl/WO3 plasmonic Z-scheme photocatalysts with different contents of Ag/AgCl nanoparticles (NPs) were prepared through a facile ultrasonic precipitation method in geothermal water, wherein the geothermal water served as the chlorine source. Then the photocatalytic activity was investigated by degradation of 4-Aminobenzoic acid (4-ABA) under visible-light irradiation. It was found that the as-prepared 50 wt% Ag/AgCl/WO3 photocatalyst showed the highest photocatalytic efficiency with 25.12 and 3.53 times higher than those of pure WO3 and Ag/AgCl, respectively. The active species trapping experiments indicated that h+ and ·O2- were key factors in 4-ABA photodegradation process. The possible plasmonic Z-scheme photocatalytic mechanism of photocatalytic reaction for 4-ABA degradation was proposed based on systematical characterizations. We hope this paper could give new ideas for further exploiting geothermal energy to design and fabricate highly efficient visible-light-driven photocatalysts for environmental remediation.

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High loading carbon nanotubes deposited onto porous nickel yarns by solution imbibition as flexible wire-shaped supercapacitor electrodes Chaoqun Kang, Dashun Cao, Yuejiao Liu, Zhiwei Liu, Ruiqing Liu, Xiaomiao Feng, Dan Wang, Yanwen Ma 2018, 27(3): 836-842.  DOI: 10.1016/j.jechem.2017.05.009 摘要 ( 1323 )   The deposition of active materials directly onto metal wires is a general strategy to prepare wire-shaped electrodes for flexible and wearable energy storage devices. However, it is still a critical challenge to coat active materials onto the aimed metal wires because of their smooth surface and small specific surface area. In this work, high porous nickel yarns (PNYs) was fabricated using commercial nylon yarns as templates through step-wise electroless plating, electroplating and calcination processes. The PNYs are composed of multiplied fibers with hollow tubular structure of 5-10 μm in diameter, allowing the imbibition of carbon nanotubes (CNTs) solution by a facile capillary action process. The prepared CNTs/PNY electrodes showed a typical electrochemical double layer capacitive performance and the constructed allsolid flexible wire-shaped symmetric supercapacitors provided a specific capacitance of 4.67 F/cm3 with good cycling stability at a current density of 0.6 A/cm3.

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Synergistic effect of chitin nanofibers and polyacrylamide on electrochemical performance of their ternary composite with polypyrrole Michael A. Smirnov, Maria P. Sokolova, Natalya V. Bobrova, Alexander M. Toikka, Pierfrancesco Morganti, Erkki Lahderanta 2018, 27(3): 843-853.  DOI: 10.1016/j.jechem.2017.06.002 摘要 ( 1634 )   Development of simple methods for preparation of polymeric electrode materials with nanofibrous network structure is a perspective way toward cheap supercapacitors with high specific capacitance and energy density. In this work one-pot synthesis of electroactive ternary composite based on polypyrrole, polyacrylamide and chitin nanofibers with beneficial morphology was elaborated. Ternary system demonstrates better electrochemical performance in comparison with both polypyrrole-polyacrylamide and polypyrrole-chitin binary composites. Possible mechanism of synergistic effect of simultaneous influence of polyacrylamide and chitin nanofibers on the formation of composite's structure is discussed. The highest attained specific capacitance of electroactive polypyrrole in ternary composite reached 249 F/g at 0.5 A/g and 150 F/g at 32 A/g. Symmetrical supercapacitor was assembled using the elaborated electrode material. High specific capacitance 89 F/g and good cycling stability with capacitance retention of 90% after 3000 cycles at 2 A/g were measured.

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Ordered Nafion® ionomers decorated polypyrrole nanowires for advanced electrochemical applications Ruili Sun, Zhangxun Xia, Huanqiao Li, Fenning Jing, Suli Wang 2018, 27(3): 854-858.  DOI: 10.1016/j.jechem.2017.07.005 摘要 ( 1404 )   Fabrication of novel electrode materials with ordered proton-migration channels is an effective strategy to enhance the proton conductivity of the electrode for polymer electrolyte membrane fuel cells. Here we report the electrochemical fabrication of ordered Nafion® ionomers decorated polypyrrole nanowires to construct the ordered proton-migration channels. Based on the electrostatic interaction between Nafion® ionomers and the polymer intermediate, ordered Nafion® ionomers decorated polypyrrole nanowires could be fabricated via chronoamperometry with varying contents of Nafion® ionomers. The morphologies, charge-storage performances, electron conductivity and proton conductivity of the composites are investigated by scanning electron microscopy, cyclic-voltammetry, galvanostatic charge-discharge measurement and electrochemical impedance spectroscopy. With the modification effect of Nafion® ionomers on polypyrrole nanowires, the composite shows greater ordered structure relative to another without Nafion® ionomers and the electrochemical performances change with the content of Nafion® ionomers. The composite could achieve a high specific capacitance of 356 F/g at 1 A/g with a 0.62-fold enhancement compared to polypyrrole nanowires without Nafion® ionomers. It also displays a superior electrical conductivity of 49 S/cm and a quite high proton conductivity of 0.014 S/cm at working conditions of fuel cells, which are associated with the requirements of fuel cells and have the potential to be the electrode material for a large range of electrochemical energy conversion devices.

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One-step synthesis of carbon-supported copper nanoparticles from biomass for N-arylation of pyrazole Wenjing Li, Yongjun Gao, Pei Tang, Yao Xu, Ding Ma 2018, 27(3): 859-865.  DOI: 10.1016/j.jechem.2017.06.003 摘要 ( 1266 )   Carbon-supported copper catalyst was prepared for the first time in one-step with copper nitrate and corn stalk through calcination under different temperatures. Uniformly dispersed nanoparticles were obtained and were identified to be Cu(0) and Cu(I) in XRD patterns. Excellent catalytic activity and selectivity were achieved in the N-arylation of pyrazole under ligand and protection gas free conditions. About 90.4% of product yield was achieved with only 0.5 mol% of copper catalyst (Cu-C-300), which was considerably more efficient than previous reports. XPS results suggested that the N-arylation of pyrazole activity was closely related to the surface Cu(I) species.

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Bendable tube-shaped supercapacitor based on reduced graphene oxide and Prussian blue coated carbon fiber yarns for energy storage Mohd. Khalid, Ana M. B. Honorato 2018, 27(3): 866-873.  DOI: 10.1016/j.jechem.2017.06.011 摘要 ( 1250 )   Carbon fiber yarns (CFY) are promising as a new type of flexible building blocks for the construction of flexible architectures for the energy storage applications. The main hurdle with CFY is how to make them high energy and power capable by using economically and environmentally viable materials. Here, we report reduced graphene oxide (rGO) and Prussian blue (PB) coated CFY, derived from a facile electrochemical process at room temperature for supercapacitor electrodes. The PB coated CFY and rGO coated CFY electrodes exhibit the excellent gravimetric capacitance of 339 F/g and 160.2 F/g, respectively, in aqueous KCl electrolyte in three-electrode cell configuration. When we coupled these electrodes inside the flexible plastic tube and separated by the electrolyte wet filter paper in order to construct flexible architecture, the resulting device delivers excellent specific energy of 52.1 Wh/kg and 26.5 Wh/kg with offering specific power of 3100 W/kg and 14400 W/kg respectively, under a wide operating potential of 1.8 V with excellent rate capability. The device shows high tolerance towards bending, and retained its efficiency to the capacitance after being bent at an angle of 360° for 200 bending cycles.

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Ceria on alumina support for catalytic pyrolysis of Pavlova sp. microalgae to high-quality bio-oils Tevfik Aysu, Javier Fermoso, Aimaro Sanna 2018, 27(3): 874-882.  DOI: 10.1016/j.jechem.2017.06.014 摘要 ( 1347 )   In this work, we report for the first time the in-situ catalytic pyrolysis of Pavlova sp. microalgae, which has been performed in a fixed-bed reactor in presence of Ce/Al2O3-based catalysts. The effects of pyrolysis parameters, such as temperature and catalyst were studied on the products yield distribution and biooil composition, among others. Results showed that all catalysts increased the bio-oil yield with respect to the non-catalytic runs and reduced the O/C ratio from 0.69 (Pavlova sp.) to 0.1-0.15, which is close to that of crude oil. In terms of bio-oil oxygen content, MgCe/Al2O3 presented the best performance with a reduction of more than 30%, from 14.1 to 9.8 wt%, of the oxygen concentration in comparison with thermal pyrolysis. However, NiCe/Al2O3 gave rise to the highest aliphatics/aromatics fractions. The elemental and gas analysis indicates that N was partially removed from the catalytic bio-oils in the gas phase in forms of NH3 and HCN.

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Core-shell structured Ru-Ni@SiO2: Active for partial oxidation of methane with tunable H2/CO ratio Yixuan Dou, Yijun Pang, Lingli Gu, Yifan Ding, Wu Jiang, Xinzhen Feng, Weijie Ji, Chak-Tong Au 2018, 27(3): 883-889.  DOI: 10.1016/j.jechem.2017.07.011 摘要 ( 1941 )   This study demonstrated that a Ru-Ni bimetallic core-shell catalyst (0.6%Ru-Ni)@SiO2 with a proper surface Ru concentration is superior in achieving better catalytic activity and tunable H2/CO ratio at a comparatively lower reaction temperature (700℃). Compared to the impregnation method, the hydrothermal approach leads to a highly uniform Ru distribution throughout the core particles. Uniform Ru distribution would result in a proper surface Ru concentration as well as more direct Ru-Ni interaction, accounting for better catalyst performance. Enriched surface Ru species hinders surface carbon deposition, but also declines overall activity and H2/CO ratio, meanwhile likely enhances Ni oxidation to certain degree under the applied reaction conditions. Over the current (m%Ru-Ni)@SiO2 catalyst, the formation of fibrous carbon species is suppressed, which accounts for good stability of catalyst within a TOS of 10 h.

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Efficient microwave-assisted production of biofuel ethyl levulinate from corn stover in ethanol medium Yuxuan Zhang, Xue Wang, Tao Hou, Huan Liu, Lujia Han, Weihua Xiao 2018, 27(3): 890-897.  DOI: 10.1016/j.jechem.2017.06.010 摘要 ( 1253 )   Levulinate esters are versatile chemicals that have been used in various fields. Herein, the production of ethyl levulinate (EL) from corn stover was investigated under microwave irradiation. Several reaction parameters, including acid concentration, reaction temperature, reaction time, and liquid-to-solid mass ratio, were investigated to evaluate the reaction conditions. Response surface methodology (RSM) was employed to optimize the reaction conditions for the production of EL. A quadratic polynomial model was fitted to the data with an R2 value of 0.93. The model validation results reflected a good fit between the experimental and predicted values. A high conversion yield (58.1 mol%) was obtained at the optimum conditions of 190℃, 30.4 min, 2.84 wt% acid, and 15 g/g liquid-to-solid mass ratio. Compared with conventional heating, microwave irradiation facilitated the conversion of corn stover to EL by dramatically shortening the reaction time from several hours to ~30 min. Thus, microwave-assisted conversion of corn stover to EL is an efficient way of utilizing a renewable biomass resource.

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Modulating the CO methanation activity of Ni catalyst by nitrogen doped carbon Yaping Lin, Pan Li, Tingting Cui, Xiulian Pan, Xinhe Bao 2018, 27(3): 898-902.  DOI: 10.1016/j.jechem.2017.06.008 摘要 ( 1323 )   Nitrogen doping has been proved to be an effective way to modify the properties of graphene and other carbon materials. Herein, we explore a composite with nitrogen doped carbon overlayers wrapping SiC substrate as a support for Ni (Ni/CN-SiC) and evaluate its effects on the methanation activity. The results show that both the activity and stability of Ni are enhanced. Characterization with STEM, XRD, XPS, Raman and H2-TPR indicates that nitrogen doping generates more defects in the carbon overlayers, which benefit the dispersion of Ni. Furthermore, the reduction of Ni is facilitated.

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Highly selective/enantioselective Pt-ReOx/C catalyst for hydrogenation of L-malic acid at mild conditions Bair S. Bal'zhinimaev, Eugene A. Paukshtis, Alexey P. Suknev, Nikita V. Makolkin 2018, 27(3): 903-912.  DOI: 10.1016/j.jechem.2017.07.018 摘要 ( 1594 )   The catalyst preparation strategy was based on a strict introduction sequence of rhenium and platinum precursors and their strong interaction with carbon support resulted in the formation of 0.5 nm Pt-ReOx species of atomic dispersion, where platinum is metallic, while monolayer rhenium is partially oxidized (Re2+). The reaction kinetics was studied taking into account the process of L-malic acid association leading to the formation of inactive cyclic oligomeric species. High TOFs (ca. 50 h-1), selectivities (ca. 99%) and stability of Pt-ReOx/C catalysts in aqueous-phase hydrogenation of L-malic acid, which are close to those of the homogeneous pincer type complexes, were revealed at mild conditions (T=90-130℃). Taking into account that (i) hydrogenation reaction occurred 2-3 orders of magnitude faster than its racemization and (ii) association of L-malic acid dominates at low temperatures and in a concentrated solution, special reaction conditions that allow obtaining chemically and optically (ee > 99%) pure (S)-3-hydroxy-γ-butyrolactone and (S)-1,2,4-butanetriol were found. Basing on HAADF-STEM, EDX, XPS, and kinetic studies, the structure of active species and basic reaction pathways are proposed.

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Electrodeposition of Zn(O,S) (zinc oxysulfide) thin films: Exploiting its thermodynamic and kinetic processes with incorporation of tartaric acid Qiao Cheng, Dong Wang, Huanping Zhou 2018, 27(3): 913-922.  DOI: 10.1016/j.jechem.2017.07.020 摘要 ( 1367 )   Zn(O,S) (zinc oxysulfide) is an important chalcogenide material recently reported to be potentially applied as electrode buffers in thin film solar cells. Both vacuum and solution approaches have enabled the fabrication of Zn(O,S) films. However they either require extreme conditions and high energy consumption for synthesis, or suffer from lack of controllability mainly due to the thermodynamic and kinetic distinction between ZnO and ZnS during film growth. Here we demonstrated an effective electrodeposition route to obtain high-quality Zn(O,S) thin films in a controllable manner. Importantly, tartaric acid was employed as a secondary complexing agent in the electrolyte to improve the film morphology, as well as to adjust other key properties such as composition and absorption. To elucidate the vital role that tartaric acid played, thermodynamic and kinetic processes of electrodeposition was investigated and discussed in detail. The accumulative contribution has shed light on further exploit of Zn(O,S) with tunable properties and optimization of the corresponding electrodeposition process, for the application in thin film solar cells.

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Synthesis and electrochemical performance of micro-nano structured LiFe1-xMnxPO4/C (0 ≤ x ≤ 0.05) cathode for lithium-ion batteries Chunyang Li, Guojun Li, Xiaomei Guan 2018, 27(3): 923-929.  DOI: 10.1016/j.jechem.2017.08.006 摘要 ( 1432 )   Micro-nano structured LiFe1-xMnxPO4/C (0 ≤ x ≤ 0.05) cathodes were prepared by spray drying, followed by calcination at 700℃. The spherical LiFe1-xMnxPO4/C (0 ≤ x ≤ 0.05) particles with the size of 0.5 to 5.0 μm are composed of lots of nanoparticles of 20 to 30 nm, and have the well-developed interconnected pore structure. In contrast, when Mn doping content is 3 mol% (x=0.03), the LiFe0.97Mn0.03PO4/C demonstrates maximum specific surface area of 31.30 m2/g, more uniform pore size and relatively better electrochemical performance. The initial discharge capacities are 161.59, 157.04 and 153.13 mAh/g at a discharge rate of 0.2, 0.5 and 1 C, respectively. Meanwhile, the discharge capacity retentions are ～100% after 120 cycles. The improved electrochemical performance should be attributed to higher specific surface, smaller polarization voltage, and a high Li+ diffusion rate due to the micro-nano porous structure and lattice expansion produced by Mn doping.

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Thioetherification of isoprene and butanethiol on transition metal phosphides Tianyu Ren, Mingfeng Li, Yang Chu, Jixiang Chen 2018, 27(3): 930-939.  DOI: 10.1016/j.jechem.2017.07.017 摘要 ( 1395 )   Thioetherification between mercaptan and diolefin is an efficient process to remove mercaptans in FCC gasoline at mild condition, during which the selective hydrogenation of diolefin to monoolefin is also expected. Here, SiO2 supported transition metal (Fe, Co, Ni, Mo and W) phosphides were tested for the thioetherification of isoprene and butanethiol on a fixed-bed reactor at 120℃ and 1.5 MPa H2, and their structure before and after reaction was characterized by means of XRD, HRTEM, N2 sorption, CO chemisorption, NH3-TPD, XPS and TG. It was found that, among different metal phosphides, MoP/SiO2 showed the best performance, and the optimal nominal MoP loading was 25%. Apart from the nature of metal, the density of metal and acid sites determined the catalyst performance. Metal site was mainly responsible for hydrogenation of isoprene, while acid site dominantly contributed to the thioetherification and the polymerization of olefins. Moreover, a balance between metallic and acidic functions is required to arrive at a desired performance. Excessive metal sites or acid sites led to the over-hydrogenation of isoprene or the severe polymerization of olefins, respectively. 25%MoP/SiO2 was tested for 37 h time on stream, and butanethiol conversion maintained at 100%; although isoprene conversion remarkably decreased, the selectivity to isopentenes exceeded 80% after reaction for 11 h. We suggest that the deactivation of MoP/SiO2 is mainly ascribed to the butanethiol poisoning and the carbonaceous deposit, especially the former.

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Fabrication and application of hierarchical mesoporous MoO2/Mo2C/C microspheres Xiaoyan Li, Qinggui Xiao, Hongling Zhang, Hongbin Xu, Yi Zhang 2018, 27(3): 940-948.  DOI: 10.1016/j.jechem.2017.09.008 摘要 ( 1480 )   Hierarchical mesoporous MoO2/Mo2C/C microspheres, which are composed of primary nanoparticles with a size of about 30 nm, have been designed and synthesized through polymer regulation and subsequent carbonization processes. The as-synthesized microspheres were characterized by XRD, Raman, SEM, TEM, XPS measurements and so on. It was found that polyethylene glycol acted as a structure-directing agent, mild reducing agent and carbon source in the formation of these hierarchical mesoporous MoO2/Mo2C/C microspheres. Moreover, the electrochemical property of the microspheres was also investigated in this work. Evaluated as an anode material for lithium ion batteries, the hierarchical mesoporous MoO2/Mo2C/C electrode delivered the discharge specific capacities of 665 and 588 mAh/g after 100 cycles at current densities of 100 and 200 mA/g, respectively. The satisfactory cycling performance and controllable process facilitate the practical applications of the hierarchical mesoporous MoO2/Mo2C/C as a potential anode material in high-energy density lithium-ion batteries.