Rigid Confinement and Interfacial Electronic Polarization Enable Highly Selective SiO₂@C/Sn Catalysts for...

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.