Supported Au nanoparticles on TiO2 aerogel: A sustainable defect-engineered photocatalyst for enhanced CO2 cycloaddition under visible light and mild condition

초록

The efficient conversion of carbon dioxide (CO2) into value-added chemicals under mild and sustainable conditions is of increasing importance for mitigating greenhouse gas emissions. Herein, we report the synthesis of Au-decorated titanium dioxide (TiO2) aerogels (Au@TiO2) as a visible-light-responsive photocatalyst for the cycloaddition of CO2 to epoxides. The TiO2 aerogel, prepared via sol-gel and supercritical drying methods, offers a high surface area and mesoporous structure. Au nanoparticles, incorporated through deposition-precipitation, expand the absorption spectrum into the visible range and promote charge separation via localized surface plasmon resonance. Enhanced photocatalytic activity is attributed to the synergistic effects of oxygen vacancies, Ti3+ species, and Au nanoparticles, which facilitate both CO2 activation and electron-hole separation. Under visible light irradiation for 6 h, the catalyst achieves up to 98% epoxide conversion and 90 % selectivity, with excellent recyclability over five cycles. Notably, the system also maintains high activity under natural sunlight, achieving 74% conversion. These findings demonstrate the potential of Au@TiO2 aerogels as a sustainable photocatalyst for CO2 utilization under ambient conditions.

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