Modified synthesis of BiVO4 and effect of doping (Mo or W) on its photoelectrochemical performance for water splitting

Abstract

The photoelectrochemical (PEC) water splitting approach is an interesting concept due to abundant solar energy source and economical viability. However, it is challenging to realize the theoretical potential of photoactive materials mainly because of intricate interactions between sunlight, semiconductors and liquid solutions. BiVO4 is one such promising material because of its favorable valence and conduction band position with a bandgap of ∼2.4 eV. In this work, thin films of BiVO4 (2 cm X 2 cm surface area) have been prepared through modified synthesis route by using robust USP technique. Further, BiVO4 doped with Mo or W elements of different atomic concentrations (3, 5, 7 and 9 at.%) have been prepared. The results indicate that doping of Mo and W in BiVO4 shown ∼2.5 times of higher photocurrent density as compared to pristine BiVO4. Poor electron–hole separation yield is one of the main limiting factors for BiVO4. The purpose of Mo or W-doping in this study is to increase the electron–hole separation yield which is resulted by improving the electron transport properties. Mo or W played a role of donor dopants by compensating cation vacancies or electrons, which contribute to increase in conductivity. Both structural and performance characterization of electrodes have been carried out to corroborate with the results. Increase in charge carrier density and decrease in charge transfer resistance unfolds the reason behind increase in photoelectrochemical performance.

Keywords

• BiVO4
• Doping
• Water splitting
• Ultrasonic spray pyrolysis
• Photocurrent​ density
• Performance characterization