Mechanochemical synthesis of Ni-Co bimetallic catalyst for enhanced hydrogenation of carbon dioxide to methane

Using renewable hydrogen and inexpensive catalysts, the catalytic hydrogenation of CO2 to CH4 is a promising strategy for storing renewable energy. Herein, a Ni-Co bimetallic catalyst was developed with a mechanochemical synthesis method for highly active and selective CO2 methanation. Under conditions of 360 degrees C, 0.1 MPa and 9600 mL h- 1 gcat -1 , the selectivity to CH4 achieves 99.8 % at a CO2 conversion of 84.5 % and a CH4 space-time yield (STY) of 1325.6 g kg-1 h- 1, outperforming the previous reports under similar reaction conditions. The transfer of electrons from Ni to Co can result in the formation of electron-rich Co species, which not only enhances CO2 adsorption but also facilitates H2 dissociation through the electron donation and back-donation mechanism. Experimental and theoretical investigations demonstrate that CO2 methanation commences with CO2 dissociation into CO* and O* species, subsequently proceeding with carbon terminal hydrogenation, followed by the execution of three exothermic reactions via CH*, CH2*, and CH3* species. This work contributes to the design and synthesis of cheap and efficient catalysts for hydrogenation of CO2 to CH4.