Vastly Enhanced BiVO₄ Photocatalytic OER Performance by NiCoO₂ as Cocatalyst

Abstract

Abstract Here, a simple and efficient preparation of NiCoO 2 nanoparticle modified nanoporous bismuth vanadate (BiVO 4 ) thin film and its application in photoelectrocatalytic (PEC) oxygen evolution reaction (OER) is demonstrated. The role of NiCoO 2 in the composite electrode (BiVO 4 /NiCoO 2 ) 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 BiVO 4 /NiCoO 2 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 BiVO 4 /NiCoO 2 is three times that of BiVO 4 and significantly higher than most literature values. The BiVO 4 /NiCoO 2 nanocomposite shows/possess a high charge separation efficiency (η surface ) of ≈72% as compared to only 23% for pure nanoporous BiVO 4 at 1.23 V versus RHE, which demonstrates convincing role of NiCoO 2 in the composite electrode. Both the excellent photocurrent density and great operational stability of this BiVO 4 /NiCoO 2 nanocomposite makes it a promising photocatalytic material for practical applications.