Enhanced photocurrent density for photoelectrochemical catalyzing water oxidation using novel W-doped BiVO and metal organic framework composites.

Doping heteroatoms and decorating co-catalyst are intensively applied to improve photocatalytic ability of BiVO. In this study, it is the first time to design W-doped BiVO coupling MIL-101(Fe) as photocatalyst for water oxidation using electrodeposition and hydrothermal processes. Similar system with Mo as dopant has been reported, but the dopant plays important roles on electrochemical performance. It is worthy to study the efficient system with different dopant. Doping amount of W is optimized to achieve high carrier density without creating serious recombination sites. MIL-101(Fe) is decorated on W-doped BiVO to suppress surface recombination, create accessible active sites and improve water oxidation kinetics. Optimized W-doped BiVO/MIL-101(Fe) electrode shows a high photocurrent density of 4.00 mA/cm at 1.23 V versus reversible hydrogen electrode (V) under air mass 1.5-global simulated light illumination without hole scavenger in electrolyte, due to large electrochemical surface area, high carrier density and small charge-transfer resistance. The W-doped BiVO and BiVO electrodes merely show photocurrent densities of 2.96 and 1.72 mA/cm at 1.23 V, respectively. Photocurrent retention higher than 95.5% is obtained for W-doped BiVO/MIL-101 (Fe) electrode under continuous illumination for 6300 s, suggesting lasting photocatalytic ability of this novel W-doped BiVO/MIL-101(Fe) electrode.