The effect of silver doping on photoelectrochemical (PEC) properties of bismuth vanadate for hydrogen production

Bismuth vanadate (BVO) as one of the promising photoanodes suffers from low charge transport mobility and conductivity. Here, dip coating of successive layers of bismuth vanadate (BVO) precursor were utilized to prepared BVO photoanode. Ag-doped BVO electrodes were also prepared by adding a trace amount of Ag+ in the bismuth vanadate precursor and codepositing Ag with the BVO film. In the Ag-doped BVO, Ag+ ions substitutionally replaced Bi3+ ions and increased the electron concentration in BVO. The photocurrent density and photoconductivity of Ag-doped BVO were monitored by changing the loading percentage of Ag (1–5%). At optimum Ag-doping percentage (2% Ag-doped BVO), the photocurrent density is found to be 5.5-fold greater than that of pure BVO. Deterministic investigation indicated that the enhanced PEC performance of the 2% Ag-BVO was attributed to significantly increased donor concentration (30-fold), greater visible light absorption, decreased recombination process of charge carriers (9-fold), thinner space charge layer (6-fold) and reduced flat band potential (16%). The water splitting experiment showed that the total generated H2 after 2 h of irradiation for 2% Ag-BVO was estimated as 5.2 μmol cm-2 and the equivalent value for O2 was 2.70 μmol cm-2.