H-Bonds in Carbon Quantum Dot-anchored C₃N₅ to Boost Proton-Coupled Electron Transfer for Piezoelectric-Driven...

Tuning proton-coupled electron transfer (PCET) is a promising strategy to boost the oxygen reduction reaction (ORR) for hydrogen peroxide (H₂O₂) synthesis, but the slow transmission rate of protons and electrons to active sites remains a significant bottleneck. To address this, we developed an H-bond-driven PCET process based on carbon quantum dot-anchored C₃N₅ (CQDs-C₃N₅) for piezo-catalytic H₂O₂ synthesis. CQDs-C₃N₅ exhibited a remarkable piezo-catalytic synthesis rate of 5025 μmol g^-1 h^-1 under ambient conditions, surpassing that of most reported piezoelectric materials. This efficiency is attributed to the intermolecular H-bonds between CQDs and C₃N₅, which significantly accelerate PCET in the ORR. The piezoelectric-generated charges, from the dipole field of the C₃N₅ plane, and protons in water, were rapidly transferred to the C rings of CQDs via H-bond networks. This process facilitated the adsorption of oxygen onto the C2 sites adjacent to the carboxyl groups of CQDs, which in turn led to the formation of H₂O₂ through a rapidly protonated, indirect 2e^- pathway. Additionally, a piezo-self-Fenton reaction system was constructed for oxytetracycline-rich wastewater purification, with effectively effects on chemical oxygen demand, antibiotic-resistant bacteria and antibiotic-resistant genes degradation, etc. This study highlights the critical role of H-bond networks for tuning PCET in the ORR and provides a comprehensive understanding for the precise control of catalytic reaction kinetics through molecular structural engineering.