In2S3/AgIO3 photoanode coupled I−/I3− cyclic redox system for solar-electrocatalytic recovery of H2 and S from toxic H2S

Abstract The abundant availability of toxic H 2 S in many industrial and natural resources and its low thermodynamic decomposition makes it a viable economic source for the production of environmentally clean fuel (H 2 ). Here, a highly efficient In 2 S 3 /AgIO 3 photoanode and Pt/C–based waterproofed carbon fibre cathode were prepared for the recovery of H 2 and S from toxic H 2 S in a cyclic redox system of I − /I 3 − . The H 2 S was oxidized to S by I 3 − in the photoanode compartment and H + was efficiently reduced to H 2 in the photocathode region. A maximum H 2 and S production rate of ∼0.26 mmol h −1  cm −2 and ∼0.23 mmol h −1  cm −2 were achieved, respectively and the photocurrent density of ∼0.9 mA cm −2 was attained during the entire operation. The In 2 S 3 /AgIO 3 photoanode exhibited high energy conversion efficiency and polysulfides were not detected after the reaction, suggesting that the toxic H 2 S was completely converted into H 2 and S. The proposed system with I − /I 3 − redox provides an energy-sustaining method for simultaneous treatment of toxic H 2 S and clean fuel production.