Engineering doping and defect in graphitic carbon nitride by one-pot method for enhanced photocatalytic hydrogen evolution

Hydrogen energy, as one clean energy, is one of the important ways to decarbonize in the future. The advancement of doping and constructing defect engineering in graphitic carbon nitride (g-C₃N₄) show promise for artificial photosynthesis for H₂ evolution using solar energy. Unfortunately, it is still difficult to generate g-C₃N₄ that has been co-modified by doping and defect and investigate their synergistic effects. In this study, potassium thioacetate was used first-time as a potassium source and dehydrogenation agent to prepare g-C₃N₄ decorated by K⁺ ions and cyano groups with enhanced H₂ evolution by a one-step method in an air atmosphere. The presence of K⁺ ions can increase the density of electron clouds in the delocalized π bond of the heptazine ring. The cyano group may successfully delocalize the solitary valence electrons in conjugated heterocycles since it is a potent electron-withdrawing group. These outcomes allow the modified catalysts to achieve improved H₂ evolution activity, reduced interfacial transfer resistance, and increased light absorption and photocurrent. Finally, K(0.05)-CN's photocatalytic hydrogen evolution rate (HER) rose to 1319 μmol h⁻¹ g⁻¹, which is five-fold better than that of CN, and the normalized HER reached 118 μmol h⁻¹ m⁻², which was much higher than other reports. This research not only offers a fresh approach to creating photocatalysts with good H₂ evolution efficiency but also advances a deep understanding of how structural defects and alkali metal doping affect photocatalytic activity.