Nitrogen‐Doped Carbon Polyhedrons Confined Fe–P Nanocrystals as High‐Efficiency Bifunctional Catalysts for Aqueous Zn−CO₂ Batteries

Emerging Fe bonded with heteroatom P in carbon matrix (FePC) holds great promise for electrochemical catalysis, but the design of highly active and cost‐efficient FePC structure for the electrocatalytic CO 2 reduction reaction (CO 2 RR) and aqueous ZnCO 2 batteries (ZCBs) is still challenging. Herein, polyhedron‐shaped bifunctional electrocatalysts, FeP nanocrystals anchored in N‐doped carbon polyhedrons (Fe‐P@NCPs), toward a reversible aqueous ZnCO 2 battery, are reported. The Fe‐P@NCPs are synthesized through a facile strategy by using self‐templated zeolitic imidazolate frameworks (ZIFs), followed by an in situ high‐temperature calcination. The resultant catalysts exhibit aqueous CO 2 RR activity with a CO Faradaic efficiency up to 95% at −0.55 V versus reversible hydrogen electrode (RHE), comparable to the previously best‐reported values of FeNC structure. The as‐constructed ZCBs with designed Fe‐P@NCPs cathode, show the peak power density of 0.85 mW cm −2 and energy density of 231.8 Wh kg −1 with a cycling durability over 500 cycles, and outstanding stability in terms of discharge voltage for 7 days. The high selectivity and efficiency of the battery are attributed to the presence of highly catalytic FeP nanocrystals in N‐doped carbon matrix, which can effectively increase the number of catalytically active sites and interfacial charge–transfer conductivity, thereby improving the CO 2 RR activity.