Carbon dioxide (CO2) was converted into formate (HCO2) in a catalytic reduction system mainlycomposed of potassium borohydride (KBH4) and nanoscale bimetallic nickel–copper alloy (NBN–C), inwhich, the average CO2 conversion efficiency of 41.92% was obtained under the optimal experimentalconditions, with a HCO2selectivity of 53.42%. Various characterization methods were employed toinvestigate the physicochemical properties of NBN–C and the results indicated that NBN–C was a coreshellmesoporous catalyst with key active sites containing Ni0 and Cu0, at which the catalytic reduction ofCO2 took place. The reaction mechanism was proposed based on these characterizations and relevantliteratures.