• • TPCN3 achieves a photocatalytic H2O2 production rate of 1.74 mmol g−1 h−1, a 13.4-fold enhancement over pristine PCN, directly addressing the low efficiency bottleneck in solar-driven H2O2 synthesis.
• • The D-A configuration with TAPT donor expands the π-conjugated system and induces a strong built-in electric field, which accelerates intramolecular charge separation and suppresses recombination, as confirmed by transient absorption spectroscopy.
• • TPCN3 exhibits significantly faster degradation kinetics toward various emerging contaminants compared to PCN, demonstrating dual functionality in both energy conversion and environmental remediation.
• • The molecular copolymerization strategy provides a scalable and metal-free route to modulate charge dynamics in carbon nitride, offering a cost-effective alternative to conventional anthraquinone process for H2O2 production.