Increasing the Photocatalytic Activity of BiVO4 by Naked Co(OH)2 Nanoparticle Cocatalysts

Bismuth vanadate (BiVO4 or BVO) is one of the most studied photocatalysts for water oxidation because its excellent visible light absorption and appropriate band energy positions. However, BVO presents a low charge mobility high electron–hole recombination rate. To address these fundamental limitations, this study proposes coating previously synthesized phase-pure monoclinic scheelite with different amounts naked cobalt (further oxidized to hydroxide) nanoparticles (NPs) via modified magnetron sputtering deposition. The resulting BVO/Co were investigated methylene blue (MB) photodegradation, photocatalytic oxygen evolution, photoelectrochemical (PEC) oxidation. In MB photodegradation tests, sample prepared deposition time 5 min (BVO/Co(5 min)) presented highest photoactivity (k = 0.06 min?1) compared other times 0.01–0.02 min?1), as well pristine 0.04 min?1). A similar trend was evidenced PEC oxidation, where photocurrent density 23 µA.cm?2 at 1.23 V (vs. RHE) observed BVO/Co(5 min) sample, value 4.6 higher BVO. Finally, an O2 evolution more than two that increased performance ascribed visible-light absorption, lesser recombination, enhanced transfer liquid/solid interface. Co(OH)2 NPs can be considered effective strategy improve target catalytic reactions, including pollutant photodegradation.