Defect Engineering of g-C₃N₄ Nanosheets for Enhanced Piezoelectric H₂ Evolution

Recent advancements in piezocatalysis for hydrogen production from water under ambient conditions have garnered significant attention. Traditional g-C₃N₄ sheets, characterized by their microscale dimensions and in-plane polarization, face limits in piezoelectric catalysis due to extended charge transfer distances and the confinement of reaction sites to sheet edges. In this study, N vacancies (N_v) and Cl dopants were introduced into the g-C₃N₄ matrix by incorporating ammonium chloride into the urea precursor during the calcination process. These modifications reduced charge transfer distances in the plane and shifted the reaction sites from the edges to the surface, leading to more efficient charge separation and an increased number of active sites. As a result, the hydrogen generation rate improved by 2.6-fold from 763 to 1961 μmol/g/h. This research presents a straightforward yet impactful strategy to enhance the piezo-catalytic performance of two-dimensional g-C₃N₄ materials.