Boosting the Photoactivity of BiVO4 Photoanodes by a ZnCoFe‐LDH Thin Layer for Water Oxidation

Monoclinic bismuth vanadate (BiVO4) has been used as an efficient photoanode material for photoelectrochemical water oxidation owing to its suitable band gap and nontoxicity. Nevertheless, the practical application of BiVO4 photoanode has been severely limited by the surface charge recombination and sluggish kinetic, which leads to the obtained photoactivity of BiVO4 is much lower than its theoretical value. In this case, ZnCoFe‐LDH thin layer is conformally decorated on the porous BiVO4 photoanode through a simple electrodeposition process. The results show that a boosted photoactivity and a remarkably enhanced photocurrent density (3.43 mA cm−2 at 1.23 VRHE) are attained for BiVO4/ZnCoFe‐LDH. In addition, the optimized BiVO4/ZnCoFe‐LDH photoanode exhibits significant negative shift in the onset potential (0.51 VRHE to 0.21 VRHE), promotes charge separation efficiency (49.3% to 60.4% in the bulk, 29.6% to 61.9% on the surface at 1.23 VRHE) and enhanced IPCE efficiency (25.5% to 54.7% at 425 nm) compared with that of bare BiVO4 photoanode. It is demonstrated that the boosted photoactivity of BiVO4/ZnCoFe‐LDH photoanode is mainly ascribed to the synergy effects of the formation of p‐n heterojunction between ZnCoFe‐LDH and BiVO4 to accelerate the photogenerated charge transfer and separation, broaden light absorption, as well as promote the surface water oxidation kinetics. A ZnCoFe‐LDH layer has been in‐situ decorated on a BiVO4 photoanode through a simple electrodeposition process and exhibits synergistic effects on the boosted PEC water oxidation activity of the BiVO4 photoanode.