Oxidized Platinum Cocatalyst and Self-Assembled Graphene over Graphitic Carbon Nitride for Photocatalytic Hydrogen Evolution

Thenanostructural design of graphitic carbon nitride (g-C3N4) plays a primary role in addressing the drawbacksposed by low surface area, which results in poor dispersion of accessibleactive sites in the reaction media of bare g-C3N4. Here, we report the solid-state structure transformation throughsolvothermal treatment of bulk g-C3N4 in anenvironmentally sustainable organic solvent. The grid-like structureof the monolayered g-C3N4 nanosheets was achievedusing a facile solvothermal process. The formation of self-assembledgraphene on g-C3N4 during the process facilitatedcharge transfer and separation on the photocatalyst, as confirmedby density functional theory calculations. The grid-like structureof the g-C3N4 contributed to the formation ofa platinum oxide cocatalyst, while the formation of metallic platinumwas observed in the bulk g-C3N4 sample. Theplatinum oxide cocatalyst enhanced the hydrogen evolution rate (HER)by inhibiting the reversible reaction pathway of hydrogen gas to protons.As a result, the platinum support on the grid-like structure of g-C3N4 and self-assembled graphene hybrid (hCN-G) achievea photocatalytic H-2 evolution rate 7.5 times that of bulkg-C3N4 (CN-b). The hCN-G contained 2.04 wt %graphene, which contributed significantly to the improvement in photocatalyticactivity. The HER of hCN-G at the stationary point reached 16 832.9 mu mol g(-1) h(-1) under 1 sunof simulated sunlight irradiation.

Automated summary

The solvothermal treatment of bulk g-C3N4 in an environmentally sustainable organic solvent resulted in the formation of grid-like structured graphene on g-C3N4, facilitating charge transfer and separation. The grid-like structure also contributed to the formation of a platinum oxide cocatalyst and significantly improved the photocatalytic activity.