AgFeS2-Nanowire-Modified BiVO4 Photoanodes for Photoelectrochemical Water Splitting

Photoelectrochemical water splitting is a promising and environmentally friendly route for the conversion of solar energy into hydrogen. However, the efficiency of this energy conversion process is low because of the limited light absorption and rapid bulk recombination of charge carriers. In this study, the combination of a novel ternary sensitizer AgFeS₂, having a narrow bandgap of 0.9 eV, with a BiVO₄ electrode is presented for the enhancement of the solar-energy-to-hydrogen conversion efficiency. The photoelectrochemical properties of this combined material were investigated and the photocurrent densities of AgFeS₂–BiVO₄ composite electrodes were greatly enhanced compared with pristine BiVO₄ (15 times higher at 0.6 V vs. Ag/AgCl under AM 1.5G illumination). The enhanced photoelectrochemical properties arise from extended light absorption, fast charge transfer and appropriate energy gap alignment. It was demonstrated that AgFeS₂ nanowires are promising inorganic sensitizers for improving the efficiency of solar water splitting.