Ag₂₄Au cluster decorated mesoporous Co₃O₄ for highly selective and efficient photothermal CO₂ hydrogenation

Photothermal carbon dioxide hydrogenation represents a promising route to reduce the emission of greenhouse gas CO₂ and produce value-added chemicals, but the selectivity and stability of photothermal catalysts need to be improved. Herein, we report the rational fabrication of well-defined Ag₂₄Au cluster decorated highly ordered nanorod-like mesoporous Co₃O₄ (Ag₂₄Au/meso-Co₃O₄) for highly efficient and selective CO₂ hydrogenation. The orderly assembled meso-Co₃O₄ nanorods were prepared via a nanocasting method, offering large surface area and abundant active sites for CO₂ adsorption and conversion. Moreover, the catalytic activity and selectivity were further improved by molecule-like Ag₂₄Au cluster decoration and reaction temperature optimization. The Ag₂₄Au/meso-Co₃O₄ composite catalyst exhibited an ultrahigh CH₄ yield rate of 204 mmol·g⁻¹·h⁻¹ and a greatly improved CH₄ selectivity of 82% for CO₂ hydrogenation, significantly higher than those of pristine meso-Co₃O₄ catalyst. The mechanism of the photothermal catalytic performance improvement was verified by CO₂ temperature-programmed desorption and time-resolved transient photoluminescence, revealing that CO₂ molecules underwent a vigorous adsorption and rapid activation process over Ag₂₄Au/meso-Co₃O₄. The hot electrons created by the localized surface plasmon resonance effect of Ag₂₄Au clusters facilitated the charge transfer for subsequent multi-electron CO₂ hydrogeneration processes, resulting in a significant increase in the productivity and selectivity for CO₂-to-CH₄ conversion. This work suggests that the rational coupling of well-defined metal atom clusters and ordered transition metal compound nanostructures could open a new avenue towards photo-induced green chemistry processes for efficient CO₂ recycling and reutilization.