Photoelectrochemical oxygen evolution with cobalt phosphate and BiVO4 modified 1-D WO3 prepared by flame vapor deposition

We demonstrate the cobalt phosphate (Co-Pi) modified 1-D WO3/BiVO4 nanowire heterojunction photoanode as oxygen evolution catalyst for photoelectrochemical (PEC) water splitting application. WO3 nanowires were prepared by flame vapor deposition (FVD) process and BiVO4 nanoparticles were spin-coated on top of WO3 nanowires. In order to improve oxygen evolution kinetics, WO3/BiVO4 heterojunction photoanode was modified by photo-assisted electrodeposition of Co-Pi. Co-Pi improve the PEC water oxidation efficiency of 1 D-WO3/BiVO4 by reducing the charge recombination, facilitating the hole transfer and reducing the overpotential of oxygen evolution reaction. The optimum amount of Co-Pi for high photocurrent density was proposed. The loaded Co-Pi has enhanced the overall PEC performance showing largely shifted onset potential (∼450 mV) with significantly increased photocurrent (2.7 times at 1.23 V vs. RHE). The prepared composite photoanode of 1-D WO3/BiVO4/Co-Pi shows the higher incident photon to current efficiency and applied bias photon-to-current efficiency than without Co-Pi loading. We obtain the highest level of PEC performance with WO3/BiVO4/Co-Pi heterojunction composite photoanode which is based on 1-D framework of WO3 prepared by facile, rapid and economical FVD in this study.