High-throughput characterization of structural and photoelectrochemical properties of a Bi-Mo-W-O thin-film materials library

A Bi-W-Mo-O thin-film materials library was fabricated by combinatorial reactive magnetron sputtering. The composition spread was investigated using high-throughput methods to determine crystalline phases, composition, morphology, optical properties, and photoelectrochemical performance. The aurivillius phase (Bi${}_2$O${}_2$)${}^{2+}$ (Bi${}_M$(W${}_{1-N}$Mo${}_N$)${}_{M-1}$O${}_{3M+1}$)${}^{2-}$ is the predominantly observed crystal structure, indicating that the thin films in the library are solid solutions.With increasing amounts of Mo $\widehat{=}$ 7–22% the diffraction peak at 2θ = 28° $\widehat{=}$ [131] shifts due to lattice distortion, the photoelectrochemical activity is increasing up to a wavelength of 460 nm with an incident photon to current efficiency (IPCE) of 4.5%, and the bandgap decreases. A maximum photocurrent density of 31 μA/cm${}^2$ was measured for Bi${}_{31}$W${}_{62}$Mo${}_7$O${}_z$ at a bias potential of 1.23 V vs. RHE (0.1 M Na${}_2$SO${}_4$).