title: Incorporation of Mo and W into nanostructured BiVO4 films for efficient photoelectrochemical water oxidation.
abstract: Porous, nanostructured BiVO4 films are incorporated with Mo and W by simultaneous evaporation of Bi, V, Mo, and W in vacuum followed by oxidation in air. Synthesis parameters such as the Bi : V : Mo : W atomic ratio and deposition angle are adjusted to optimize the films for photoelectrochemical (PEC) water oxidation. Films synthesized with a Bi : V : Mo : W atomic ratio of 46 : 46 : 6 : 2 (6% Mo, 2% W) demonstrate the best PEC performance with photocurrent densities 10 times higher than for pure BiVO4 and greater than previously reported for Mo and W containing BiVO4. The films consist of a directional, nanocolumnar layer beneath an irregular surface structure. Backside illumination utilizes light scattering off the irregular surface structure resulting in 30-45% higher photocurrent densities than for frontside illumination. To improve the kinetics for water oxidation Pt is photo-deposited onto the surface of the 6% Mo, 2% W BiVO4 films as an electrocatalyst. These films achieve quantum efficiencies of 37% at 1.1 V vs. RHE and 50% at 1.6 V vs. RHE for 450 nm light.
authors.affiliation: Departments of Chemical Engineering and Chemistry and Biochemistry, Center for Electrochemistry, Texas Materials Institute, Center for Nano- and Molecular Science, University of Texas at Austin, 1 University Station C0400, Austin, TX 78712, USA. mullins@che.utexas.edu.
authors.forename: Sean P
authors.initials: SP
authors.lastname: Berglund
authors.forename: Alexander J E
authors.initials: AJ
authors.lastname: Rettie
authors.forename: Son
authors.initials: S
authors.lastname: Hoang
authors.forename: C Buddie
authors.initials: CB
authors.lastname: Mullins