Precisely designed cobalt single atom on ZrO2 support for chemical CO2 fixation 

 

The presence of single atoms as active sites on a metal oxide support can dramatically enhance catalytic activity. Here, we demonstrate that cobalt-doped ZrO₂ constitutes a single atom catalyst where each Co⁺² ion is active for CO2 fixation. The synthesized Co/ZrO₂ catalyst was characterized by EXAFS and STEM to confirm the presence of isolated Co⁺² on the ZrO₂ support. The STEM-EDS data showed uniform distribution of Co over the surface of the ZrO2 support. The catalytic results reveal that Co active sites on ZrO₂ enhance catalytic performance and provide 100% conversion into carbonate products in the presence of trace amounts of tetrabutylammonium bromide (TBAB). When undoped ZrO₂ and Co₃O₄ impregnated ZrO₂ catalyst was utilized for comparison, less than 50% conversion of epoxides was obtained. The single-atom catalyst (SAC) showed a broad substrate scope, solvent-free reaction and higher catalytic activity and selectivity.