期刊
ACS APPLIED MATERIALS & INTERFACES
卷 11, 期 8, 页码 7990-7999出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsami.8b20785
关键词
electrochemical impedance spectroscopy; solar water oxidation; water oxidation kinetics; photoanodes; water oxidation catalysts
资金
- Basic Science Research Program through the National Research Foundation of Korea (NRF) - the Ministry of Science and ICT of Korea [2015R1C1A1A02037698, 2018R1D1A1A02046918]
- Nano-Material Technology Development Program through the National Research Foundation of Korea (NRF) - Ministry of Science and ICT of Korea [2017M3A7B4052802]
- Technology Development Program to Solve Climate Changes through the National Research Foundation of Korea (NRF) - Ministry of Science and ICT of Korea [2017M1A2A2087630]
- National Research Foundation of Korea [2018R1D1A1A02046918, 2015R1C1A1A02037698] Funding Source: Korea Institute of Science & Technology Information (KISTI), National Science & Technology Information Service (NTIS)
We studied the kinetics of photoelectrochemical (PEC) water oxidation using a model photoanode BiVO4 modified with various water oxidation catalysts (WOCs) by electrochemical impedance spectroscopy. In particular, we prepared BiVO4 photoanodes with catalytic multilayers (CMs), where cationic polyelectrolytes and anionic polyoxometalate (POM) WOCs were assembled in a desired amount at a nanoscale precision, and compared their performance with those with well-known WOCs such as cobalt phosphate (CoPi) and NiOOH. Our comparative kinetics analysis suggested that the deposition of the CMs improved the kinetics of both the photogenerated charge carrier separation/transport in bulk BiVO4 due to passivation of surface recombination centers and water oxidation at the electrode/electrolyte interface due to deposition of efficient molecular WOCs. On the contrary, the conventional WOCs were mostly effective in the former and less effective in the latter, which is consistent with previous reports. These findings explain why the CMs exhibit an outstanding performance. We also found that separated charge carriers can be efficiently transported to POM WOCs via a hopping mechanism due to the delicate architecture of the CMs, which is reminiscent of natural photosynthetic systems. We believe that this study can not only broaden our understanding on the underlying mechanism of PEC water oxidation but also provide insights for the design and fabrication of novel electrochemical and PEC devices, including efficient water oxidation photoanodes.
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