High Light Absorption and Charge Separation Efficiency at Low Applied Voltage from Sb-Doped SnO2/BiVO4 Core/Shell Nanorod-Array Photoanodes

BiVO4 has become the top-performing semiconductor among photoanodes for photoelectrochemical water Oxidation. However, BiVO4 photoanodes are still limited to a fraction of the theoretically possible photocurreut at low applied voltages because of modest. charge transport properties and a trade-off between light absorption and charge separation efficiencies. Here, we investigate photoanodes composed of thin layers of BiVO4 coated onto Sb-doped SnO2, (Sb:SnO2) nanorodarrays (Sb:SnO2/BiVO4 NRAs) and demotistrate a high. value for the product of light absorption and charge separation efficiencies (eta(abs) x eta(sep)) of similar to 51% at an applied voltage of 0.6 V versus the reversible hydrogen electrode, as determined by integration of the quantum efficiency over the standard-AM 1.5G spectrum. To the best of our knowledge, this is one of the highest eta(abs) x eta(sep) efficiencies achieved to date at this voltage for nanowire-core/BiVO4-shell photoanodes. Moreover, although WO3 has recently been extensively studied as a tore nanowire material for core/shell BiVO4 photoanodes, the Sb:SnO2/BiVO4 NRAs generate larger photocurrents, especially at low applied voltages. In addition, we present control experiments on planar Sb:SnO2/BiVO4 and WO3/BiVO4 heterojunctions, which indicate that Sb:SnO2 is more favorable as a core material. These results indicate that integration Of Sb:SnO2 nanorod cores with other successful strategies such as doping and coating with oxygen evolution catalysts can move the performance of BiVO4 and related semiconductors closer to their theoretical potential.