Pt-doped g-C3N4 photocatalyst for simultaneous hydrogen production and value-added chemical synthesis under visible light.

Abstract

Metal-free photocatalysts, especially through the use of semi-conductors g-C₃N₄ (graphitic carbon nitride, CN) have become a prominent topic due to their sustainable advantages and promising effectiveness in hydrogen (H₂) production. However, CN material requires specific modifications, since its efficacy under visible light suffers from fast recombination of electron/hole pairs (e^‒/h⁺), slow charge transfer and limited surface area. In this study, we present the synthesis of CN via the thermal treatment of urea and melamine mixture. To enhance its crystallinity and photocatalytic performance, Pt nanoparticles were loaded onto CN by simple incipient wetness impregnation method. The H₂ production was investigated through the potential application of aromatic alcohols including anisyl (AA), benzyl (BA), piperonol (PA), and methanol (M) alcohols, as sacrificial reagents. H₂ production was achieved using the hybrid Pt-CN system with the added benefit of value-added organic synthesis under visible light exposure. The Pt-CN photocatalyst exhibited varying H₂ evolution rates on the alcohol used as sacrificial reagent, with the PA yielding to the highest rate of 503.5 µmol·g^-1·h^-1. Stability assessments confirmed the robustness of the synthesized Pt-CN photocatalyst across three consecutive visible light driven experiments. Notably, piperonal (P) synthesis occurred along with H₂ production under visible light. Comprehensive structural, textural, morphologic, optoelectronic and electrochemical characterizations were performed correlating the Pt-CN's properties with its visible photocatalytic performance.