Graphitic carbon nitride (g-C₃N₄) has emerged as a promising photocatalyst due to its layered architecture, ease of synthesis, and notable photocatalytic efficiency. Despite these advantages, insights into its site-specific catalytic behavior and reaction kinetics remain limited. In this study, we synthesized ultrathin g-C₃N₄ nanosheets via thermal exfoliation, achieving a high surface area (307.35 m² g⁻¹) and enhanced hydrogen evolution performance (2008 μmol h⁻¹ g⁻¹) with a quantum efficiency of 4.62% at 420 nm. Employing single-molecule fluorescence microscopy, we visualized catalytic activity with ~10 nm spatial resolution, identifying distinct reactivity patterns across structural features such as wrinkles, edges, and basal planes. Notably, wrinkles and edges demonstrated photocatalytic rates 20 and 14.8 times greater than the basal plane, driven by localized band structure modulation. While steric hindrance increased adsorption on basal planes, DFT calculations further clarified the energetics of reactant and product interactions. We also investigated strain engineering, showing that tensile strain in folded wrinkles enhances performance via favorable band alignment (type I), improved light harvesting, and directional charge transport. This work highlights the influence of strain and nanoscale structural features on g-C₃N₄ photocatalysis, providing valuable insights for the rational design of advanced 2D materials for solar-driven chemical energy conversion.
References
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