Construction of floatable copper/corncob biochar composite with LSPR effect for CO2 capture and efficient photo-thermal catalytic conversion

The synthesis of high-value chemicals through photothermal reduction of carbon dioxide is of great significance for addressing the energy shortages and environmen-tal challenges, however the poor heating effect of powder catalysts results in low CO2 reduction efficiency. Herein, a Cu/corncob biochar honeycomb composite was synthesized using a facile impregnation/calcination method. The corncob biochar exhibited a honeycomb morphology with high specific surface area and abundant adsorption sites due to its porous surface structure. The localized heating and the generation of high-energy hot electrons were facilitated by the localized surface plasmon resonance (LSPR) induced by Cu nanoparticles. Consequently, the photo-thermal catalytic reduction of CO2 was enhanced, significantly contributing to the high conversion of CO2 to methanol in pure water. Notably the 5% wt Cu/corncob biochar demonstrated a CO2 adsorption capacity of 52.59 cm3/g under conditions of 25 ℃ and 1 bar. Simultaneously, under full-spectrum irradiation, Cu nanoparticles catalyzed the formation of key intermediates *COOH and *CH3O species during the CO2 conversion process, resulting in a high CH3OH yield of 63.3 μmol/g. This work provides a promising strategy to reduce environmental pollution caused by solid waste accumulation and carbon dioxide emissions.