Vastly Enhanced BiVO4 Photocatalytic OER Performance by NiCoO2 as Cocatalyst

Abstract

AbstractHere, a simple and efficient preparation of NiCoO2 nanoparticle modified nanoporous bismuth vanadate (BiVO4) thin film and its application in photoelectrocatalytic (PEC) oxygen evolution reaction (OER) is demonstrated. The role of NiCoO2 in the composite electrode (BiVO4/NiCoO2) is twofold: OER cocatalyst and band structure modifier. It improves surface reaction kinetics for PEC OER and enhances charge separation efficiency simultaneously, which is believed to be a determining factor for the unprecedentedly high PEC OER performance of this BiVO4/NiCoO2 nanocomposite. The photocurrent density of 3.6 mA cm−2 at 1.23 V versus RHE in 0.1 m potassium phosphate buffered (pH = 7) electrolyte by BiVO4/NiCoO2 is three times that of BiVO4 and significantly higher than most literature values. The BiVO4/NiCoO2 nanocomposite shows/possess a high charge separation efficiency (ηsurface) of ≈72% as compared to only 23% for pure nanoporous BiVO4 at 1.23 V versus RHE, which demonstrates convincing role of NiCoO2 in the composite electrode. Both the excellent photocurrent density and great operational stability of this BiVO4/NiCoO2 nanocomposite makes it a promising photocatalytic material for practical applications.