Highly conformal deposition of ultrathin cobalt acetate on a bismuth vanadate nanostructure for solar water splitting

Abstract

In this work, the effect of photochemically modifying nanoporous bismuth vanadate in Co²⁺ solution in acetate buffer (abbreviated as Co–Ac) on water oxidation was thoroughly studied. Modification of photoanode surfaces with the electrocatalyst Co–Ac has yielded a ∼450 mV cathodic shift in the onset potential and more than threefold higher photocurrent density at 1.23 V than that of pristine BiVO₄. Structural and mechanistic studies indicate that Co–Ac effectively acts as a true catalyst on BiVO₄ in that Co–Ac can boost the photoelectrochemical properties of the BiVO₄ underlayer by mediating hole extraction across the photoexcited semiconductor–electrolyte interface. With Co–Ac as the catalyst, water oxidation becomes much more facile by overcoming the unproductive surface electron–hole recombination. This work considers the potential application of this simple surface modification approach for other candidate photoanodes.