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.