Density functional theory calculations have been applied to explore a series of 12 selected nano-hollow cages A12X12 for catalysis of CO2 to hydrogenated products. The reactivity order among the nanocages is found to be A12N>12A12P>12A12As12. Among the 12 selected nano-hollow cages, only six nanocages are able to activate CO2 molecule. Surprisingly, endohedral doping of alkali metals (Li, Na, K) leads to a decrease in band gap, increases charge separation and hereby increases the adsorption energies. Additionally, while the undoped A12As12 nanocages remain inert for CO2 activation alkali metal doped A12As12 nanocages showed an increased level of CO2 activation. Furthermore, among the alkali metals, potassium doped endohedral nanocages showed increased adsorption energy and the least energy barrier for CO2 activation. These findings have immense importance to provide new ideas for the design of potential nanocages catalyst for CO2 reduction.