Boosting CO2 Hydrogenation via Histidine-Modulated Highly Dispersed Cu/SiO2 Catalysts

Abstract Copper (Cu)-based catalysts have been extensively investigated for CO2 hydrogenation. Their practical application is often hindered by poor thermal stability and a strong tendency for Cu nanoparticles to agglomerate at elevated temperatures. Although various strategies have been explored to improve the performance of Cu catalysts, many rely heavily on introducing metal promoters or oxide supports. In this work, histidine-modulated Cu catalysts supported on SiO2 were synthesized by dispersing Cu nanoparticles and incorporating nitrogen-containing species via coordination with an organic ligand. The histidine-modulated Cu catalysts exhibit significantly higher metal dispersion (∼17%) than the unmodulated catalyst (∼5%). The histidine-modulated Cu catalysts showed enhanced catalytic performance, with CO2 conversion more than an order of magnitude higher than that with the conventional Cu/SiO2 catalysts (9.2% vs 0.8%), accompanied by a moderate rise in methanol selectivity (11.4% vs 19.4%) at 260 °C, 2.0 MPa, and 3000 mL·gcat−1·h−1 for the 10 wt % Cu catalysts. XPS and in situ DRIFT analyses further reveal that histidine modulation effectively enhances CO2 adsorption and facilitates Cu+ stabilization. Overall, the histidine-modulated Cu catalysts are much less susceptible to sintering, thereby enhancing stability and offering a practical and sustainable route to more efficient CO2-to-methanol catalysis.