Formation of Small Polaron and Polaronic Charge Transfer within BiVO4 Photocatalyst

Abstract

Harnessing the power of solar energy plays an essential role in developing renewable energy technologies to supplement or perhaps replace fossil fuel utilization. The green energy technology has the potential to address the challenges of growing energy demand and climate changes around the world. Production of H2 from water splitting via photo-electrochemical process is one of the potential green technologies. BiVO4 is one of the best photoanode material for water oxidation as well as photo-catalyst for H2 evolution via water splitting. Despite being an efficient photo absorber material, it has poor charge transport properties. It is anticipated that some of the conduction electrons get bind to specific lattice sites and form polarons, and hence, the charge transfer within this material happens via the polaron hopping from one lattice site to another. In this present study, we have studied the polaron formation at cationic lattice sites and calculated the site to site polaron hopping barrier along a specific hopping pathway in the framework of density functional theory (DFT) with the Hubbard parameter U for self-energy correction of localized d electrons. Finally, the polaron transfer rate, mobility, and diffusion coefficient will also be presented. The work of MNH is supported by NSF grant #1609811. We also acknowledge the computational time from Texas Advanced Computing Center (TACC).