Achieving efficient incorporation of Π-electrons into graphitic carbon nitride for markedly improved hydrogen generation.

The past decade has witnessed rapid advances in graphitic carbon nitride (g-C3N4) as it is metal-free and affords highly stable hydrogen (H2) generation. Notably, density functional theory calculations show that C-substitution for N in g-C3N4 can increase Π-electron availability and in turn significantly increase the photocatalytic H2 generation. However, creating such C-incorporated g-C3N4 has proven challenging owing to the higher electronegativity of N over C. Here, we report a rapid and highly efficient strategy for introducing C into g-C3N4 by copolymerizing Π-electrons-rich barbituric acid with melamine via a facile microwave-assisted heating, thereby eliminating the issues in conventional electric furnace heating, such as the severe volatilization, due to the mismatch on the sublimation temperatures of barbituric acid and melamine. The g-C3N4 catalyst after optimizing the C-doping content actively generates increased amounts of H2 under visible light exposure with the highest H2 generation rate of 25.0 μmol h-1, nearly 20 times over that using g-C3N4 produced by conventional electric furnace heating of two identical monomers (1.3 μmol h-1). As such, the microwave-assisted heating strategy may stand out as an extremely simple route to incorporating π-electrons into g-C3N4 with markedly improved photocatalytic performance.