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 CO2 reduction reaction (CO2RR) and aqueous Zn-CO2 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-CO2 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 CO2RR 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 CO2RR activity.

Automated summary

Emerging Fe-P-C structure, specifically Fe-P nanocrystals anchored in N-doped carbon polyhedrons (Fe-P@NCPs), has shown great potential for electrochemical catalysis in both CO2 reduction reaction (CO2RR) and Zn-CO2 batteries (ZCBs). These bifunctional electrocatalysts are synthesized through a simple strategy using self-templated zeolitic imidazolate frameworks (ZIFs) and high-temperature calcination. The resulting Fe-P@NCPs exhibit comparable CO2RR activity to the best-reported Fe-N-C structures, with a CO Faradaic efficiency of up to 95% at -0.55 V vs reversible hydrogen electrode (RHE). When used as cathode materials in ZCBs, the Fe-P@NCPs demonstrate peak power density of 0.85 mW cm(-2), energy density of 231.8 Wh kg(-1), cycling durability over 500 cycles, and outstanding stability in discharge voltage for 7 days. The presence of highly catalytic Fe-P nanocrystals in N-doped carbon matrix contributes to the high selectivity and efficiency of the battery by increasing catalytically active sites and improving interfacial charge-transfer conductivity for enhanced CO2RR activity.