Modulating hole extraction and water oxidation kinetics in CoPi/Au/BiVO4 photoanode via strong metal-support interactions

Abstract

Photoelectrochemical (PEC) water splitting using bismuth vanadate (BiVO₄) as a photoanode shows promise for renewable hydrogen production. Depositing cobalt phosphate (CoPi) on the BiVO₄ photoanode as an oxygen evolution cocatalyst (OEC) is an effective method to improve the PEC performance. However, the CoPi/BiVO₄ photoanode still faces challenges in terms of slow interface photogenerated carrier transport. Herein, we utilize the advantage of the classical strong metal-support interaction (SMSI) between Au and BiVO₄ to prepare a CoPi/Au/BiVO₄ (SMSI-CoPi/Au/BiVO₄) photoanode. Due to the formation of SMSI, the accumulated electrons at the interface of CoPi/Au induce the accelerated extraction of photogenerated holes. Meanwhile, the active electron density of CoPi is increased, leading to improved water oxidation kinetic. As a result, the SMSI-CoPi/Au/BiVO₄ photoanode exhibits a high photocurrent density of 5.01 mA cm⁻² at 1.23 V versus the reversible hydrogen electrode and an applied bias photon-to-current efficiency of 1.78%. This work highlights a novel approach to enhance hole transfer and water oxidation kinetics of OEC/BiVO₄ composite photoanodes, offering the great potential of using SMSI for PEC water splitting.