A H2-evolving photocathode based on direct sensitization of MoS3 with an organic photovoltaic cell

Abstract

An organic solar cell based on a poly-3-hexylthiophene (P3HT):phenyl-C₆₁-butyric acid (PCBM) bulk hetero-junction was directly coupled to molybdenum sulfide resulting in the design of a new type of photocathode for the production of hydrogen. Both the light-harvesting system and the catalyst were deposited by low-cost solution-processed methods, i.e. spin coating and spray coating respectively. Spray-coated MoS₃ films are catalytically active in strongly acidic aqueous solutions with the best efficiencies for thicknesses of 40 to 90 nm. The photocathodes display photocurrents higher than reference samples, without a catalyst or without coupling with a solar cell. Gas chromatography analysis confirms the light-induced hydrogen evolution. The addition of titanium dioxide in the MoS₃ film enhances electron transport and collection within thick films and therefore the performance of the photocathode.