The built-in electric field and spin-pinning effect in BiVO4/Fe0.4Co0.6Se2/Co(Fe)OxHy for enhanced photoelectrochemical water oxidation

Photoelectrocatalytic water splitting is a promising method for producing green and clean energy. In this research, a three-layer composite photoanode BiVO4/Fe0.4Co0.6Se2/Co(Fe)OxHy, named as M@BFOH5, is prepared by a in situ electro-oxidation reconstitution and magnetization method. Through constructing a p-n heterojunction BiVO4/Fe0.4Co0.6Se2, a built-in electric field is formed to accelerate electron transfer in the cross-layer channels. The spin-pinning effect caused by ferromagnetic semiconductor Fe0.4Co0.6Se2 induce spontaneous polarization in the ultra-thin Co(Fe)OxHy layer, which is favorable for conductivity of the passivation layer (Co(Fe)OxHy). The results demonstrate the exceptional oxygen reduction reaction performance of M@BFOH5, achieving a photocurrent density of 4.99 mA cm−2 at 1.23 V in comparison to the reversible hydrogen electrode. This represents an enhancement of 3.1 and 1.37 times over BiVO4 and BFOH5, respectively. Additionally, the charge separation and charge injection efficiencies significantly increased to 92.44 % and 82.68 %, correspondingly. This subtle catalyst is designed to help accelerate oxygen reduction reaction.