Highly efficient Co centers functionalized by nitrogen-doped carbon for the chemical fixation of CO2

Abstract

CO₂, the main greenhouse gas, has received considerable attention due to environmental issues. From a scientific perspective, CO₂ as a cheap and abundant carbon source, could be applied in synthesizing more valuable chemicals such as urea, formic acid, and cyclic carbonates. However, the high bond energy of CO (750 kJ mol⁻¹) and the non-polarity property make CO₂ molecules difficult to activate. In this paper, we have carefully designed a low-cost, stable and, most importantly, highly efficient Co-based heterocatalyst Co@N_xC functionalized by nitrogen-doped carbon to activate CO₂ molecules and convert it into cyclic carbonates. The CO₂ conversion process could be triggered at very mild conditions (60 °C and 1 bar CO₂). We carefully adjusted the nitrogen content in the carbon support to enhance the catalytic performance of Co centers via the interface effect. Consequently, the optimal catalyst displayed extraordinary activity toward the cycloaddition of CO₂ with styrene oxide as high conversion (92%) and selectivity (>99%) were achieved in 4 h without byproducts.