Role of Polarons in Water Splitting: The Case of BiVO4

We study hole and electron polarons in BiVO4 at finite temperature through hybrid functional molecular dynamics simulations. Through the thermodynamic integration method, we obtain the transition levels corresponding to the localized charges at 300 K. We observe that the polaron levels achieved in this way lie significantly closer to each other than those at 0 K. We find both hole and electron levels to lie within the band gap, with binding energies of 0.11 and 0.88 eV, respectively. Our calculations show that polaron localization significantly affects the alignment at the solid/liquid interface and that electron hole recombination through polaronic states competes with the evolution of the water-splitting reaction in BiVO4.