Efficient bismuth vanadate homojunction with zinc and tungsten doping via simple successive spin-coating process for photoelectrochemical catalyzing water oxidation

BiVO4 is one of the promising photocatalysts for water oxidation due to its suitable band positions and narrow band gap. Doping heteroatoms in BiVO4 can increase charge concentration and develop efficient charge-transfer path via shifting conduction or valance band edges. Spin-coating method is simple and cost-effective for depositing photocatalyst on conductive substrate. It is the first time to use the simple spin-coating method for fabricating multi-layered Zn-doped and W-doped BiVO4 homojunction as photocatalyst for water oxidation. The pristine BiVO4 and single metal-doped BiVO4 electrodes are also fabricated for comparison. The charge concentration is enhanced by doping tungsten in BiVO4. The preferable type II homojunction electrode composed of Zn-doped BiVO4 bottom layer and W-doped BiVO4 top layer (W:BVO/Zn:BVO) shows the highest photocurrent density of 2.85 mA/cm2 at 1.23 VRHE under air mass 1.5 global and the smallest charge-transfer resistance of 238.34 omega. The pristine BiVO4 electrode only shows a photocurrent density of 1.88 mA/cm2 measured at the same condition. The excellent long-term stability with the photocurrent retention of 100% under continuous light illumination for 4000 s is also achieved for the optimized W:BVO/Zn:BVO electrode. This work provides a simple way to attain highly improved electrochemical performance for BiVO4 toward photoelectrochemical catalysis.

Automated summary

BiVO4 is a promising photocatalyst for water oxidation, doping heteroatoms and tungsten can enhance charge concentration and increase photocurrent density. The electrode with a Zn-doped bottom layer and W-doped top layer shows the highest photocurrent density and excellent long-term stability for water oxidation.