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

Area of Science:

• Catalysis
• Materials Science
• Electrochemistry

Background:

• The two-electron oxygen reduction reaction (2e- ORR) is a sustainable method for producing hydrogen peroxide (H2O2).
• Developing p-block metal catalysts with high activity and stability for 2e- ORR is challenging.
• Existing catalysts often suffer from migration and aggregation of active nanoparticles, leading to reduced performance.

Purpose of the Study:

• To design and synthesize a novel hierarchical core-shell catalyst (SiO2@C/Sn) for enhanced 2e- ORR.
• To improve the selectivity and production rate of H2O2 synthesis.
• To achieve long-term stability of the catalyst.

Main Methods:

• Fabrication of a hierarchical core-shell catalyst using mesoporous SiO2 as a scaffold and a conductive carbon layer.
• In-situ formation of Sn nanoparticles on the SiO2@C support.
• Electrochemical characterization including H2O2 selectivity and production rate measurements.
• In-situ spectroscopy and Density Functional Theory (DFT) calculations to elucidate reaction mechanisms.

Main Results:

• The SiO2@C/Sn catalyst demonstrated high H2O2 selectivity (>97% in alkaline, 80% in neutral media) and production rates.
• The core-shell structure effectively suppressed Sn nanoparticle aggregation and enhanced charge transport.
• The catalyst exhibited excellent long-term stability with minimal decay after 100 hours of operation.
• Interface engineering at the SiO2-carbon boundary optimized the electronic structure of Sn sites for the 2e- pathway.

Conclusions:

• The hierarchical SiO2@C/Sn catalyst offers a promising solution for efficient and stable H2O2 production.
• The synergistic effects of SiO2 confinement and the carbon layer are crucial for tuning catalytic activity and selectivity.
• The study provides fundamental insights into catalyst design for selective 2e- ORR through interface polarization coupling.