Efficiently catalyzing photo-oxidation of water by surface engineering of bismuth vanadate with nickel molybdenum oxide coverages.

Bismuth vanadate with suitable band edges is one of the efficient photocatalysts for water oxidation. Establishing heterojunction can improve electron diffusion lengths and photocatalytic ability of BiVO 4. In this work, nickel molybdenum oxide (Ni–Mo–O) and BiVO 4 heterojunction is established by the hydrothermal process with different nickel to molybdenum precursor ratios. The Ni–Mo–O/BiVO 4 electrode is applied as photoanodes for water oxidation. The growth mechanism of Ni–Mo–O on BiVO 4 surface is proposed. The Ni–Mo–O deposition amount is optimized regarding to light absorbance and charger transportation. The largest photocurrent density of 1.72 mA/cm2 at 1.23 V RHE is obtained for the optimal NiMoO 4 /BiVO 4 electrode (NM12) in the electrolyte without hole scavenger, while the pure BiVO 4 electrode only shows a photocurrent density of 0.90 mA/cm2. The NM12 electrode even presented an impressive photocurrent density of 5.39 mA/cm2 at 1.23 V RHE in the electrolyte with the hole scavenger, owing to the abundant active sites and higher light absorbance as well as the favorable synergistic effects from its suitable Ni to Mo ratio. The NM12 electrode also shows excellent long-term stability with the photocurrent retention of 83% after illumination for 6500 s. This work opens a blueprint for establishing a novel heterojunction with the adjustable metal ratio and coverage on BiVO 4. [Display omitted] • Nickel molybdenum oxide (Ni–Mo–O) and BiVO 4 heterojunction is made by hydrothermal. • Ni–Mo–O/BiVO 4 photoanode with varied Ni to Mo ratios is used for water oxidation. • The growth mechanism of Ni–Mo–O on BiVO 4 surface is proposed. • Photocurrent density of 5.39 mA/cm2 at 1.23 V RHE is got for optimal NM12 electrode. • The NM12 electrode shows an excellent photocurrent retention of 83 % after 6500 s. [ABSTRACT FROM AUTHOR]