Boosting photoelectrochemical activity of bismuth vanadate by implanting oxygen-vacancy-rich cobalt (oxy)hydroxide

Surface charge recombination is regarded as a detrimental factor that severely downgrades the photo electrochemical (PEC) performance of bismuth vanadate (BiVO4). In this work, we demonstrate defect rich cobalt (oxy)hydroxides (Co(O)OH) as an excellent cocatalyst nanolayer sheathed on BiVO4 to substantially improve the PEC water oxidation activity. The self-transformation of metal-organic framework produces an ultrathin Co(O)OH layer rich in oxygen vacancies, which could serve as a powerful hole extraction engine to promote the charge transfer/separation efficiency as well as an excellent oxygen evolution reaction catalyst to accelerate the surface water oxidation kinetics. As a result, the BiVO4/Co (O)OH hybrid photoanode achieves remarkably inhibited surface charge recombination and presents a prominent photocurrent density of 4.2 mA cm(-2) at 1.23 V vs. RHE, which is around 2.6-fold higher than that of the pristine BiVO4. Moreover, the Co(O)OH cocatalyst nanolayer significantly reduces the onset potential of BiVO4 photoanodes by 200 mV. This work provides a versatile strategy for rationally preparing oxygen-vacancy-rich cocatalysts on various photoanodes toward high-efficient PEC water oxidation. (C) 2021 Elsevier Inc. All rights reserved.

Automated summary

Surface charge recombination is a detrimental factor for bismuth vanadate (BiVO4) photo electrochemical (PEC) performance. In this study, a defect rich cobalt (oxy)hydroxides (Co(O)OH) nanolayer was demonstrated as an excellent cocatalyst on BiVO4 to greatly improve PEC water oxidation activity. The self-transformation of metal-organic framework produced an ultrathin Co(O)OH layer with oxygen vacancies, which served as a powerful hole extraction engine and an excellent oxygen evolution reaction catalyst. As a result, the hybrid photoanode of BiVO4/Co(O)OH achieved inhibited surface charge recombination and a prominent photocurrent density, around 2.6-fold higher than the pristine BiVO4. The Co(O)OH cocatalyst nanolayer also significantly reduced the onset potential of BiVO4 photoanodes. This work provides a versatile strategy for preparing oxygen-vacancy-rich cocatalysts on various photoanodes for high-efficient PEC water oxidation.