Crystal Reconstruction of Mo:BiVO<sub>4</sub>: Improved Charge Transport for Efficient Solar Water Splitting
Yoo Jae Jeong, Dong Hyun Seo, Ji hyun Baek, Min Je Kang, Bit Na Kim, Sung kyu Kim, Xiaolin Zheng, In Sun Cho
Abstract
Abstract A multifaceted Mo:BiVO 4 (mf‐BVO) photoanode is grown on F‐doped‐SnO 2 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.