Exploring the impact of surface oxygen vacancies on charge carrier dynamics in BiVO₄ photoanodes through atmospheric pressure plasma jet post-treatment for efficiency improvement in photoelectrochemical water oxidation

We have demonstrated the production of high-density surface oxygen vacancy (ov_s) in BiVO₄ (BVO) photoanodes through the post-treatment of an atmospheric pressure plasma jet (APPJ). The 3.4-fold enhancement of photocurrent density of BVO photoanodes at 1.23 V_RHE for photoelectrochemical (PEC) water oxidation due to 95 % of charge transfer efficiency at the BVO/electrolyte interface. In-situ transient absorption spectroscopy investigations provided insights into the charge carrier dynamics of the APPJ-treated BVO photoanode, revealing that abundant electrons could effectively be trapped in the ov_s states to prevent charge carrier recombination. NiOOH/FeOOH oxygen evolution co-catalyst was further decorated on the APPJ-treated BVO photoanode resulted in a remarkable photocurrent density of 3.6 mA/cm² at 1.23 V_RHE, an anodic bias photon-to-current efficiency of 1.4 % at 0.62 V_RHE, and a faradaic efficiency over 90 % in PEC water splitting. Our study provides important and novel insights into the surface vacancy engineering of metal oxides for green hydrogen production.