Computational and Photoelectrochemical Study of Hydrogenated Bismuth Vanadate

We demonstrate hydrogenation as a facile method to significantly enhance the performance of BiVO 4 films for photoelectrochemical water oxidation. Hydrogenation was performed for BiVO 4 films by annealing them in hydrogen atmosphere at elevated temperatures between 200 and 400 °C. Hydrogen gas can reduce BiVO 4 to form oxygen vacancies as well as hydrogen impurities. DFT calculation predicted that both oxygen vacancies and hydrogen impurities are shallow donors for BiVO 4 with low formation energies. These defects could increase the donor densities of BiVO 4 without introducing deep trap states. Electrochemical impedance measurements showed that the donor densities of BiVO 4 films were significantly enhanced upon hydrogenation. Hydrogen-treated BiVO 4 (H-BiVO 4 ) photoanodes achieved a maximum photocurrent density of 3.5 mA/cm 2 at 1.0 V vs Ag/AgCl, which is 1 order of magnitude higher than that of air-annealed BiVO 4 obtained at the same potential. The enhanced photoactivities were attributed to increased donor densities of H-BiVO 4, which facilitates the charge transport and collection.