In situ composite of biomass derived carbon/porous carbon nitride and its enhanced performance in solar-driven photocatalytic hydrogen evolution reaction

• Porous carbon/CN photocatalyst was successfully prepared by a simple in-situ composite method. • The solar-driven HER rate of the composite photocatalyst reached 4.98 mmol h −1 g −1 under simulated solar irradiation (AM 1.5 G). • The composite photocatalyst exhibits good cycling stability. • The intrinsic mechanisms underpinning this enhancement were elucidated through theoretical calculations. Converting waste organic biomass into functional carbon materials is regarded as a sustainable development strategy to address environmental pollution and energy crisis. In this work, carbon/porous carbon nitride (PCN) composite photothermal catalysts were prepared via an in-situ method with urea and phragmites spikelets as raw materials for the solar-driven hydrogen evolution reaction (HER). The biomass derived porous carbon, in close contact with PCN, not only acts as a charge transfer bridge facilitating the rapid separation and migration of photogenerated charges but also serves as a photothermal carrier to enhance the kinetic process of the photocatalytic reaction. Under simulated solar irradiation (AM 1.5 G), the optimal HER rate of the composite catalyst is 4.98 mmol g −1 h −1 , which is 2.1 times that of pure PCN. The physicochemical properties of the materials, including morphology, crystal structure, elemental composition and state, and energy band characteristics, were determined. Additionally, theoretical calculations were employed to explore the impact of biomass-derived porous carbon on the electronic structure and band structure of carbon nitride. This work not only broadens the range of raw materials for biomass-derived porous carbon but also provides a novel strategy for promoting photocatalytic HER through synergistic multifield effects, showing broad application prospects in the field of resource recovery and green catalysis.