Rigid Confinement and Interfacial Electronic Polarization Enable Highly Selective SiO2@C/Sn Catalysts for Two-Electron Oxygen Reduction Toward Efficient H2O2 Production.

The two-electron oxygen reduction reaction (2e- ORR) provides a sustainable route for green hydrogen peroxide (H2O2) synthesis, but the development of p-block metal catalysts that combine high activity with long-term stability remains challenging. Herein, we propose a hierarchical core-shell catalyst, SiO2@C/Sn. Mesoporous silicon dioxide (SiO2) serves as a rigid confinement scaffold to effectively suppress the migration and aggregation of Sn nanoparticles. Simultaneously, a conductive carbon layer was in-situ formed on the SiO2 surface, markedly enhancing interfacial charge transport. Importantly, the interfacial electronic structure of the Sn nanoparticles is moderately tuned by the combined effect of SiO2 confinement and the continuous electronic interface provided by the carbon layer, thereby maintaining an optimal adsorption-desorption balance for the *OOH intermediate and significantly improving selectivity toward the 2e- pathway. SiO2@C/Sn achieves H2O2 selectivity exceeding 97% and a production rate of 16.15 mol·g- 1·h- 1 in alkaline media, while 80% selectivity with a yield of 8.13 mol·g- 1·h- 1 in neutral media. The catalytic activity shows almost no decay after 100 h of continuous operation. In-situ spectroscopies combined with DFT calculations further reveal that polarization coupling at the SiO2-carbon interface induces electronic redistribution that optimizes the electronic states of Sn sites and thereby stabilizes the 2e- reaction pathway.