Coupled experimetal and theoretical study of photon absorption and charge transport in BiVO4 photoanodes for solar water splitting

Bismuth vanadate (BiVO4) has been identified as one of the most promising photoanode materials for water-splitting photoelectrochemical cells. The major limitations of BiVO4 are its relatively wide bandgap (~2.5 eV) and low electron mobility (~0.2 cm-2V-2S-1), which limit its solar-to-hydrogen conversion efficiency. In this talk we will present the results of a coupled experimental and ab initio theoretical study showing that nitrogen doping together with extra oxygen vacancies lead to both a reduction of BiVO4 band gap and to an increase of the majority carrier density and mobility. In turn these improvements lead to the applied bias photon-to-current efficiency over 2\%, a record for a single oxide photon absorber, to the best of our knowledge[1]. The “codoping” method adopted in our work could also be applied to simultaneously enhance photon absorption and charge transport in other oxides, providing new possibilities for photocatalytic materials. [1] T. Kim, Y. Ping, G. Galli and K. Choi, Nature Communications, 6,8769, (2015).