Atomic-layer deposition (ALD) of thin layers of cobalt oxide on n-type BiVO4 produced photoanodes capable of water oxidation with essentially 100% faradaic efficiency in alkaline, pH = 13 electrolytes. By contrast, under the same operating conditions, BiVO4 photoanodes without the Co oxide catalytic layer exhibited lower faradaic yields, of ca. 70%, for O2 evolution and were unstable, becoming rapidly photopassivated. High numbers (>25) of ALD cycles of Co oxide deposition gave electrodes that displayed poor photoelectrochemical behavior, but 15-20 ALD cycles produced Co oxide overlayers ∼1 nm in thickness, with the resulting photoelectrodes exhibiting a stable photocurrent density of 1.49 mA cm -2 at the oxygen-evolution potential and an open-circuit potential of 0.404 V versus the reversible hydrogen electrode, under 100 mW cm-2 of simulated air mass 1.5 illumination.
ASJC Scopus subject areas
- Materials Science(all)
- Physical and Theoretical Chemistry