A multifaceted Mo:BiVO4 (mf-BVO) photoanode is grown on F-doped-SnO2 substrates via achemical bath deposition, and the crystal reconstruction process of mf-BVO is found to boost the charge transport efficiency significantly for photoelectrochemical (PEC) water splitting. The mf-BVO exhibits columnar grains with an uncommon (121) texture with high-index facets such as (112), (020), (132), and (204). The texture and high-index facets facilitate rapid surface melting and grain fusion during thermal annealing, thus leading to crystal reconstructed micron-sized BVO grains (cr-BVO). The cr-BVO has a photocurrent density ≈50 times larger than that of mf-BVO. The reason is identified as the significantly improved charge transport efficiency resulting from the dopant activation (increased carrier concentration) and bulky grains (fewer defects). Additionally, the cr-BVO exhibits improved photocorrosion resistance compared to the nanoparticle-based BVO. After coating the oxygen evolution catalyst, the photocurrent density of cr-BVO is further increased to 4.4 mA cm−2 for water oxidation reaction at 1.23 V versus the reversible hydrogen electrode, maintaining a high and stable faradaic efficiency of over 88% for 24 h. These results demonstrate that crystal reconstruction is a facile and effective pathway to improve the charge transport efficiency, opening a new avenue for developing efficient photoelectrodes for PEC water splitting.
Y.J.J. and D.H.S. contributed equally to this work. This research was supported by the Basic Science Research Program through the National Research Foundation of Korea, funded by the Ministry of Science, ICT, and Future Planning (grant numbers NRF\u20102019R1A2C2002024 and 2021R1A4A1031357). X.L.Z. would like to thank the National Science Foundation EFRI\u2010DCheM program (Agreement Number: SUB0000425) for their generous support. J. B. would like to acknowledge the Chevron Fellowship in Energy.
