Improvement in the structural, optical, electronic and photoelectrochemical properties of hydrogen treated bismuth vanadate thin films

• BiVO4 synthesis in controlled manner by rf sputtering technique followed by annealing in hydrogen ambient.
• Reduction in surface Bi4+ and increases in density of hydroxyl groups on hydrogen treatment in BiVO4 thin films.
• Presence of small amount of V4+ species are advantageous for the enhancement of photoelectrochemical behaviour of H:BiVO4.
• Detailed experimental study on hydrogen treated BiVO4 in photoelectrochemical water splitting.
• Modulation of photoelectrochemical properties as a function of hydrogen treatment temperature.

In the present study structural, optical and electronic properties of bismuth vanadate (BiVO4) thin films prepared by rf-sputtering technique were modified by post-hydrogen treatment to improve the photoelectrochemical (PEC) performance for water oxidation. X-ray diffraction and Raman analysis do not reveal any major structural changes but show increase in crystallite size and creation of defect states, however, optical absorption studies shows changes in band gap energy values due to the creation of inter-band states on hydrogen treatment. X-ray photoelectron spectroscopy studies show that the hydrogen treatment reduces surface Bi4+ considerably and increases the density of hydroxyl groups on the BiVO4 surface. The combined effect of these changes manifests in terms of enhanced photocurrent density of 3.31 mA/cm2 (at applied potential 1.0 V versus Ag/AgCl), which is about nine time higher than the pristine BiVO4 and reduced photocurrent onset potential.