Improved charge separation via Fe-doping of copper tungstate photoanodes.

Photoelectrochemical (PEC) water splitting offers a clean pathway to renewable and sustainable energy in the near future. The key to improving the efficiency of PEC devices is the ability to find materials with suitable optoelectronic properties, and identifying, then overcoming their limitations. In this paper, we explore the photoelectrochemical performance of CuWO4 photoanodes for solar water splitting, and find that charge separation is the dominant limitation for this material. As a result, we attempt to dope the material with Fe, the first such example of doping this semiconductor for PEC water splitting. An improvement in performance is achieved for doped films which show 1.5 times the photocurrent density and a 50% higher charge separation efficiency at 1.23 V vs. RHE.