Journal of Energy Chemistry ›› 2023, Vol. 86 ›› Issue (11): 399-408.DOI: 10.1016/j.jechem.2023.07.039

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A conformal titanyl phosphate amorphous overlayer for enhancing photoelectrochemical hydrogen peroxide production

Jaekyum Kima, Young Eun Kima, Minyeong Jec, Won Tae Honga, Chang-Lyoul Leed, Tae-Hoon Kime, Sung Min Choa, Chang Hyuck Choif,g, Heechae Choic,h,*, Woo-Seok Choea,*, Jung Kyu Kima,b,*   

  1. aSchool of Chemical Engineering, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea;
    bSKKU Advanced Institute of Nano Technology (SAINT), Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea;
    cTheoretical Materials & chemistry Group, Institute of Inorganic Chemistry, University of Cologne, Greinstr. 6, 50939, Cologne, Germany;
    dAdvanced Photonics Research Institute (APRI), Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea;
    eDepartment of Materials Science and Engineering, Chonnam National University, Gwangju 61186, Republic of Korea;
    fDepartment of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea;
    gInstitute for Convergence Research and Education in Advanced Technology (I-CREATE), Yonsei University, Seoul 03722, Republic of Korea;
    hDepartment of Chemistry, Xi'an Jiaotong-Liverpool University, Suzhou 215123, Jiangsu, China
  • Received:2023-04-26 Revised:2023-07-19 Accepted:2023-07-28 Online:2023-11-15 Published:2023-11-07
  • Contact: *E-mail addresses: heechae.choi@xjtlu.edu.cn (H. Choi), checws@skku.edu (W.-S. Choe), legkim@skku.edu (J.K. Kim).

Abstract: Photoelectrochemical (PEC) H2O2 production through water oxidation reaction (WOR) is a promising strategy, however, designing highly efficient and selective photoanode materials remains challenging due to competitive reaction pathways. Here, for highly enhanced PEC H2O2 production, we present a conformal amorphous titanyl phosphate (a-TP) overlayer on nanoparticulate TiO2 surfaces, achieved via lysozyme-molded in-situ surface reforming. The a-TP overlayer modulates surface adsorption energies for reaction intermediates, favoring WOR for H2O2 production over the competing O2 evolution reaction. Our density functional theory calculations reveal that a-TP/TiO2 exhibits a substantial energy uphill for the O* formation pathway, which disfavors O2 evolution but promotes H2O2 production. Additionally, the a-TP overlayer strengthens the built-in electric field, resulting in favorable kinetics. Consequently, a-TP/TiO2 exhibits 3.7-fold higher Faraday efficiency (FE) of 63% at 1.76 V vs. reversible hydrogen electrode (RHE) under 1 sun illumination, compared to bare TiO2 (17%), representing the highest FE among TiO2-based WOR H2O2 production systems. Employing the a-TP overlayer constitutes a promising strategy for controlling reaction pathways and achieving efficient solar-to-chemical energy conversion.

Key words: Solar H2O2 production, In-situ surface reforming, Titanyl phosphate, Amorphous overlayer, Reaction pathway control