Visible light-induced hydrogen over CuFeO_2 via S_2O_3~(2-) oxidation

摘要

The properties of CuFeO_2 have been studied according to the catalytic hydrogen production upon visible light. CuFeO_2 with a low band gap E_g, a good chemical stability and a suitable flat band potential appears as a suitable candidate. The potential of photoelectrons allows favorably a thermodynamically H_2-evolution from alkaline thio-sulfate S_2O_3~(2-) solution. There is a major difference between pure and loaded oxide with some metal catalysts. Our best results have been obtained with unloaded CuFeO_2 at 50℃ and pH 13.60. Thiosulfate S_2O_3~(2-) ions can be oxidized to sulfite SO_3~(2-) and subsequently to sulfate SO_4~(2-) and the electronic exchange occurs via mediation of surface states. The quite high H_2-formation at the beginning shows a tendency towards saturation, it competes with SO_3~(2-) produced by parallel oxidation of S_2O_3~(2-).