Construction of a floatable copper/corncob biochar composite with an LSPR effect for CO2 capture and efficient photothermal catalytic conversion

Abstract

The synthesis of high-value chemicals through the photothermal reduction of carbon dioxide is of great significance for addressing energy shortages and environmental 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 a 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 localized surface plasmon resonance (LSPR) induced by Cu nanoparticles. Consequently, the photothermal catalytic reduction of CO₂ was enhanced, significantly contributing to the high conversion of CO₂ to methanol in pure water. Notably, 5% wt Cu/corncob biochar showed a CO₂ adsorption capacity of 52.59 cm³ g⁻¹ under conditions of 25 °C 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⁻¹. This work provides a promising strategy to reduce environmental pollution caused by solid waste accumulation and carbon dioxide emissions.