Stability of an H2-producing photocatalyst (Ru/(CuAg)0.15In0.3Zn1.4S2) in aqueous solution under visible light irradiation

Efficient photocatalytic water-splitting systems require stable photocatalysts that have photocatalytic activity with repeated consecutive use. This study investigated H2 production under visible light irradiation with an Ru/(CuAg)0.15In0.3Zn1.4S2 photocatalyst and KI as an electron donor. In addition, the stability and reusability of the catalyst were evaluated over multiple cycles of H2 production and catalyst regeneration. The results show that sintering temperature influenced the crystallinity and photocatalytic activity, as indicated by the X-ray diffraction analyses and H2 production rates. In particular, the catalyst sintered at 873 K yielded the highest quantum yield of 4.6% at 420 ± 5 nm of wavelength. After seven consecutive reaction cycles, the quantum yield decreased from 4.6% to 3.0% at the end of the seventh cycle. The decrease probably occurred because (1) particles of the catalyst underwent pronounced aggregation, which led to the increase in particle size; and (2) a release of significant metal ions was observed during H2 production, which led to a loss of the catalyst mass and potential changes in the photocatalytic activity. This study will help facilitate a search of stable photocatalysts for water splitting.