Metal‐Free Photocatalytic Graphitic Carbon Nitride on p‐Type Chalcopyrite as a Composite Photocathode for Light‐Induced Hydrogen Evolution

Abstract Recently, it has been shown that an abundant material, polymeric carbon nitride, can produce hydrogen from water under visible‐light irradiation in the presence of a sacrificial donor. We present herein the preparation and characterization of graphitic carbon nitride (g‐C 3 N 4 ) films on p‐type semiconducting CuGaSe 2 chalcopyrite thin‐film substrates by thermal condensation of a dicyandiamide precursor under inert‐gas conditions. Structural and surface morphological studies of the carbon nitride films suggest a high porosity of g‐C 3 N 4 thin films consisting of a network of nanocrystallites. Photoelectrochemical investigations show light‐induced hydrogen evolution upon cathodic polarization for a wide range of proton concentrations in the aqueous electrolyte. Additionally, synchrotron radiation‐based photoelectron spectroscopy has been applied to study the surface/near‐surface chemical composition of the utilized g‐C 3 N 4 film photocathodes. For the first time, it has been shown that g‐C 3 N 4 films coated on p‐type CuGaSe 2 thin films can be successfully applied as new photoelectrochemical composite photocathodes for light‐induced hydrogen evolution.