Visible light-induced hydrogen over CuFeO2 via S2O32− oxidation

The properties of CuFeO2 have been studied according to the catalytic hydrogen production upon visible light. CuFeO2 with a low band gap Eg, a good chemical stability and a suitable flat band potential appears as a suitable candidate. The potential of photoelectrons allows favorably a thermodynamically H2-evolution from alkaline thiosulfate S2O32− solution. There is a major difference between pure and loaded oxide with some metal catalysts. Our best results have been obtained with unloaded CuFeO2 at 50 °C and pH 13.60. Thiosulfate S2O32− ions can be oxidized to sulfite SO32− and subsequently to sulfate SO42− and the electronic exchange occurs via mediation of surface states. The quite high H2-formation at the beginning shows a tendency towards saturation, it competes with SO32− produced by parallel oxidation of S2O32−.