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 gcat -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.