Journal
CHEMICAL ENGINEERING JOURNAL
Volume 401, Issue -, Pages -Publisher
ELSEVIER SCIENCE SA
DOI: 10.1016/j.cej.2020.126134
Keywords
BiVO4; Oxygen vacancies; Zero-valent iron; Ultrathin FeOx layer; Ultrafast electron transport; PEC water oxidation
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Funding
- National Key Research and Development Program of China [2018YFB1502001, 2018YFE0122300]
- National Natural Science Foundation of China [21776177, 21875139]
- Shanghai International Science and Technology Cooperation Fund Project [18520744900]
- SJTU-AEMD
- SJTU Center for high Performance Computing
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Efficient separation and transport of charge is a critical issue in solar-driven water oxidation. Herein, we developed a novel, facile, controllable method based on zero-valent iron (ZVI) reduction to in-situ and synchronous generate oxygen vacancies (Ov) and FeOx oxygen evolution co-catalysts (OECs) on BiVO4 for ultrafast electron transfer and excellent photoelectrochemical (PEC) water oxidation. In this method, a moderate and controllable ZVI reduction was the critical step to ensure whole penetration of Ov from BiVO4 to FeOx layer. This is because a special galvanic cell is formed between ZVI and BiVO4, making it easy to capture oxygen atom from BiVO4 and obtain a FeOx layer (5 nm) outside simultaneously in oxygen-free annealing. The Ov can extend light absorption by narrowing bandgap and significantly improve electron mobility (8.6 x 10(-7) cm(2) s(-1)) by reducing the trap assisted recombination, which is 6.1-fold of BiVO4. Meanwhile, electron lifetime increases from 11.6 to 115.3 ms. Ultrathin FeOx layer provides more sites and dramatically reduces OER over-potential of 210 mV, resulting in fast hole-to-oxygen kinetics. A photocurrent of 3.13 mA center dot cm(-2) at 1.23 VRHE is achieved for PEC water oxidation, which is 4.6-fold of pristine BiVO4. This work provides a new path to overcome charge transport limitations and achieve enhanced solar water oxidation.
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