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

An organic solar cell based on a poly-3-hexylthiophene (P3HT): phenyl-C₆₁-butyric acid (PCBM) bulk hetero-junction was directly coupled with 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 catalyst or without coupling with a solar cell. Analysis by gas chromatography 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.