Electron Injection From B₄C to Sn Sites Optimizes *OOH Adsorption Enabling Efficient H₂O₂ Electrosynthesis

The development of efficient non-precious metal electrocatalysts is a key challenge for the sustainable electrosynthesis of H₂O₂. In this study, a Sn/B₄C composite catalyst was constructed via low-temperature pyrolysis under a hydrogen atmosphere. The optimized Sn/B₄C-3 exhibited excellent 2e^- ORR performance, achieving 93.69% H₂O₂ selectivity in 0.1 M KOH and 91.9% selectivity in 0.05 M Na₂SO₄ in RRDE measurements. In a neutral flow cell, the Sn/B₄C-3 delivered an H₂O₂ production rate of 13.33 mol g_cat ^-1 h^-1 with a Faradaic efficiency of 91.38%, and maintained operation for 130 h. XPS and in situ ATR-SEIRAS analyses reveal that electron transfer from B₄C to Sn generates electron-rich Sn centers, which optimally modulate the adsorption energy of the key *OOH intermediate. DFT calculations confirm that these centers lower the energy barrier for H₂O₂ formation and enable optimal *OOH binding, thereby steering the pathway toward selective 2e^- ORR. The catalyst maintained stable performance over 130 h of continuous operation in a flow cell. Furthermore, the in situ generated H₂O₂ solution inactivated Escherichia coli and Streptomyces griseus within 40 min, achieving 99% sterilization efficiency. This study introduces an innovative design principle for electrocatalysts based on metal-carbide synergy, promoting sustainable H₂O₂ production for applications such as microbial disinfection.