Cobalt Oxide-Coated Single Crystalline Bismuth Vanadate Photoanodes for Efficient Photoelectrochemical Chlorine Generation

Bismuth vanadate (BiVO4) is an outstanding photoanode material for photoelectrochemical water splitting. In this work, a series of single crystalline BiVO4 photoanodes are synthesized by pulsed laser deposition (PLD). Once coated with a thin layer of cobalt oxide (CoO x ) cocatalyst, also by PLD, the photoanodes support efficient photoelectrochemical generation of chlorine (Cl-2) from brine under simulated solar light. The activity of the chlorine generation reaction (ClER) is optimized when the thickness of CoO x is about 3 nm, with the faradic efficiency of ClER exceeding 60%. Detailed studies show that the CoO x cocatalyst layer is amorphous, uniform in thickness, and chemically robust. As such, the cocatalyst also effectively protects the underlying BiVO4 photoanodes against chlorine corrosion. This work provides insights into using artificial photosynthesis for byproducts that carry significant economic value while avoiding the energetically expensive oxygen evolution reactions.

Automated summary

In this study, single crystalline BiVO4 photoanodes were synthesized by pulsed laser deposition, and a thin layer of cobalt oxide cocatalyst was coated on the surface using the same method. The coated photoanodes showed efficient photoelectrochemical generation of chlorine from brine under simulated solar light. The thickness of the cobalt oxide layer was found to be optimal at 3 nm, achieving a faradic efficiency of chlorine generation exceeding 60%. Moreover, the amorphous and chemically robust cobalt oxide cocatalyst effectively protected the underlying BiVO4 photoanodes against chlorine corrosion. This work provides insights into the production of valuable byproducts using artificial photosynthesis and avoiding energy-intensive oxygen evolution reactions.