Biochar-Tailored Carbon Nitride Enables Piezo-Photocatalytic H2O2 Production via Boosted Charge Transport

Piezo-photocatalytic systems enable efficient H 2 O 2 generation, 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 H 2 O 2 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 ·O 2 – adsorption and activation via an indirect two-electron reduction pathway. The optimized PCCN-10 yields 4.61 mmol g –1 h –1 H 2 O 2 in the absence of cocatalysts, outperforming most previously reported piezo-catalysts and g-C 3 N 4 -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 H 2 O 2 production and advancing multifunctional material systems for green energy applications.