Biochar-TailoredCarbon Nitride Enables Piezo-PhotocatalyticH_<b>2</b>O_<b>2</b> Production viaBoosted Charge Transport

Piezo-photocatalytic systems enable efficient H₂O₂generation, presenting a promising mechanical-energy-to-chemical-energy conversion pathway. However, limitations, including insufficient polarization efficiency and poor directional charge transfer, persist in current piezoelectric semiconductors, constraining the photocatalytic performance. Here, we develop a biochar-tailored method to fabricate PCCN-x, a modified carbon nitride nanosheet incorporating nitrogen defects and carbon bridges, which demonstrates high efficiency in piezo-photocatalytic H₂O₂ generation. Experimental and theoretical analyses reveal that introducing nitrogen defects together with carbon incorporation creates an asymmetric configuration in the triazine unit, generating a pronounced dipole field that drives spontaneous polarization. This configuration enhances oriented charge migration at the nitrogen active sites, enabling efficient ·O₂^– adsorption and activation via an indirect two-electron reduction pathway. The optimized PCCN-10 yields 4.61 mmol g^–1 h^–1 H₂O₂ in the absence of cocatalysts, outperforming most previously reported piezo-catalysts and g-C₃N₄-based photocatalysts. Remarkably, the system sustains high piezo-photocatalytic performance (2.19 mmol g^–1 h^–1) even when operating in a pure water system. Overall, this work develops a multifield-coupled catalytic framework based on biochar-tailored defect engineering, offering a new design principle for sustainable H₂O₂ production and advancing multifunctional material systems for green energy applications.