Photoassisted Electrodeposition of Cobalt-Phosphate Cocatalyst on BiFeO3 Thin Film Photoanode for Highly Efficient Photoelectrochemical Performances of Water Oxidation

In this work, cobalt-phosphate (Co-Pi) cocatalyst is deposited on the surface of BiFeO3 (BFO) thin film photoanode for enhanced photoelectrochemical (PEC) performances. The prepared Co-Pi/BFO thin film is composed of irregular rhombohedral BFO nanoparticles which are uniformly covered with a layer of amorphous Co-Pi, and the corresponding PEC performance is remarkably improved with a negatively-shifted onset potential from -0.058 V (BFO) to -0.130 V (Co-Pi/BFO). The photocurrent density of Co-Pi/BFO thin film photoanode measured at 0 V (vs. Ag/AgCl) under visible light irradiation is as high as similar to 0.050 mA cm(-2) (nearly 8 times that of the prepared BFO thin film photoanode), which rivals or exceeds those of state-of-the-art BFO-based thin film photoelectrodes. On the basis of PEC measurement results, the enhanced PEC performance of Co-Pi/BFO photoanode can be attributed to the higher carrier concentration, the more efficient separation and transfer process of photogenerated charges and the lower electron/hole recombination probability induced by Co-Pi cocatalyst. In addition, the possible PEC mechanism of the Co-Pi/BFO photoanode is also discussed. The present work validates the feasibility of Co-Pi cocatalysts coupled with other photoanode systems for pursuing highly efficient PEC performances of water oxidation. (C) 2019 The Electrochemical Society.