Exploiting effective electrocatalysts toward electrochemical conversion of CO₂ into valued-added chemicals is highly desirable for achieving the global carbon cycle. In this work, we report the synthesis of Cu₃P/C nanocomposites by phosphatizing the copper-based metal organic framework precursor. Systematic electrochemical characterizations demonstrate the Cu₃P/C nanocomposites hold high activity and favorable selectivity towards CO₂ reduction reaction (CO₂RR) into CO, as manifested by an onset potential is about -0.25 V versus reversible hydrogen electrode (RHE) and a faradic efficiency (FE) of 47% for CO production at a relatively low potential (-0.3 V). The attractive catalytic properties might be attributed to the synergistic effect of cooper and phosphorus elements, as well as the unique structure of Cu₃P. Furthermore, we propose an asymmetrical-electrolyte Zn-CO₂ battery with the Cu₃P/C as cathode catalyst, demonstrating a decent performance with an open-circuit voltage of 1.5 V and a power density of 2.6 mW cm-2 (at 10 mA cm-2).