Enriched Photoelectrochemical Performance of Phosphate Doped BiVO 4 Photoelectrode by Coupling FeOOH and rGO

Abstract

Bismuth vanadate is a promising photoanode with a set of intrinsic limitations for water oxidation and photoelectrochemical degradation of organic pollution. FeOOH/P:BiVO4/rGO composite with a considerably small charge-transfer resistance was successfully developed by doping the BiVO4 lattice with phosphate (P:BiVO4), photo-depositing FeOOH nanoparticles on P:BiVO4 nanoparticles, and grafting reduced graphene oxide (rGO) onto the surface of P:BiVO4, in that order. This composite photoelectrode significantly improves photoelectrochemical performance originating from its effective suppression on electron-hole recombination and charge transfer at the semiconductor/electrolyte interface. The photoelectrocatalysts were systematically characterized by FTIR, XPS, SEM, TEM, UV-vis and XRD. The characterization results show that FeOOH/P:BiVO4/rGO consisted of spherical agglomerates comprising a large number of P:BiVO4 nanoparticles with an average size of approximately 10 nm. FeOOH nanoparticles were successfully loaded onto the surface of P:BiVO4 nanoparticles, and rGO layers with a thickness of approximately 4 nm were coated onto the P:BiVO4 particles. The enhanced photoelectrochemical properties were observed using linear sweep voltammetry. The mechanism underlying the observed photoelectrocatalytic activity enhancement was determined using Mott-Schottky analysis and electrochemical impedance spectroscopy. The photocurrent density of FeOOH/P:BiVO4/rGO in a Na2SO4 solution with 2,4-dichlorophenol (2,4-DCP) at 0.6 VAg/AgCl is approximately 100 times higher than that of P:BiVO4; the onset potentials of FeOOH/P:BiVO4/rGO (0.008 VAg/AgCl) is 5 times lower than that of P:BiVO4 (0.043 VAg/AgCl). It is suggested that FeOOH/P:BiVO4/rGO obtains the highest photoelectrocatalytic performance for 2,4-DCP degradation. The proposed mechanism is that the synergistic effect between FeOOH and rGO can alleviate two main limitations of P:BiVO4: suppression on the bulk recombination and interfacial recombination formed at the P:BiVO4-FeOOH junction and effective charge transfer at the semiconductor/electrolyte interface.