Interstitial Lithium Doping in BiVO₄ Thin Film Photoanode for Enhanced Solar Water Splitting Activity

As one of the most promising candidates of photoanode material, bismuth vanadate (BiVO4) has been paid wide attention and achieved remarkable progress. However, the full exploitation of solar-energy-conversion potential of bismuth vanadate (BiVO4) is still limited by poor charge transport. Introducing dopants into BiVO4 has been proved to be a feasible method to improve the photoelectrochemical water splitting performance. In this work, lithium is introduced as an interstitial dopant to crystalline BiVO4 thin film photoanode, with the aid of pulsed laser deposition (PLD). Solid-state transport characterization demonstrates increased carrier density and electron conductivity in BiVO4 bulk due to interstitial lithium doping, which also increased the photocurrent and photon-to-current conversion efficiency both by up to 20% for solar water splitting. Computational results based on density functional theory determine the effect of lithium doping on the electronic and atomic structures of BiVO4 and verify the role of lithium dopant as a shallow donor that improves the conductivity of BiVO4.