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 act as 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 a 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 similar to 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.