Enhancing photoelectrochemical water oxidation activity of BiVO4 photoanode through the Co-catalytic effect of Ni(OH)2 and carbon quantum dots

The CQDs + Ni(OH)2/BiVO4 photoanode was fabricated by introducing CQDs with fluorescence and optical properties. The CQDs + Ni(OH)2/BiVO4 photoanode exhibited a low water oxidation onset potential (∼0.2 V vs. RHE) and a photocurrent density of 3.05 mA cm−2 at a voltage of 1.23 V vs. RHE, which is about 2.5 times than that of the unmodified BiVO4 electrode, and the charge injection efficiency is 65%. Surface dynamics test showed that CQDs + Ni(OH)2/BiVO4 photoanode had higher charge transfer rate and lower charge recombination rate than BiVO4 electrode. As a cheap and stable catalyst for water oxidation, Ni(OH)2 combined with CQDs can effectively improve the migration of photogenerated electrons and holes, thereby improving the photoelectrochemical (PEC) water oxidation activity of the photoanode.