Boosting water oxidation performance of CuWO4 photoanode by surface modification of nickel phosphate

Abstract In this work, we have reported the integration of the nickel phosphate (Ni-Pi) nanoparticles on the surface of CuWO4 photoanodes for the first time, which exhibited a significant enhancement in the photocurrent and improvement in the incident photon to current efficiency (IPCE) towards the water splitting reaction under simulated sunlight irradiation. The CuWO4 photoanode was synthesized via a solid phase reaction method using WO3 nanoplates as the sacrificial template, followed by surface modification of Ni-Pi through a drop-casting technique. The CuWO4 photoanode retained its excellent photostability after the surface modification with Ni-Pi. Time-resolved photoluminescence spectra revealed that the charge recombination dynamics of the CuWO4 photoanodes was greatly inhibited upon the loading of Ni-Pi nanoparticles. The electrochemical impedance spectra confirmed the efficient charge separation and enhanced interfacial charge transfer over the Ni-Pi-modified CuWO4 photoanodes. Thus, a significant decrease of charge recombination and a favourable photohole transfer could be the main reason underlying the remarkable performance of developed composite photoanodes, where Ni species of Ni-Pi entrapped the holes to facilitate the water oxidation kinetics.