Optimizing particle morphology: Atomic iron–nitrogen centers with graphitic‐N for highly efficient CO2 electroreduction

Abstract

AbstractTransition metal‐coordinated nitrogen sites on carbon catalysts (M‐N‐C) hold potential for CO2 electroreduction (CO2ER), but optimal morphology and active sites are unclear. We introduce a novel approach, developing zeolitic imidazolate framework‐8 (ZIF‐8)‐derived carbon catalysts with Fe‐N and graphitic‐N sites (Fe2‐NC) via molecular confinement and thermal activation. Fine‐tuning ZIF‐8 size and activation temperature yielded 44.98% active N sites. The 300 nm Fe2‐NC catalyst displayed outstanding CO2‐to‐CO conversion, with a 170 mV overpotential and 94.3% Faradaic efficiency at −0.5 V, outperforming state‐of‐the‐art materials. Enhanced CO2ER kinetics and conductivity contributed to this superiority. Results highlight the correlation between maximum CO Faradaic efficiency and cumulative Fe‐N/graphitic‐N sites, dependent on size and activation. The 300 nm Fe2‐NC in a gas diffusion electrode‐loaded flow cell achieved a 15.3‐fold CO partial current density increase. In a Zn‐CO2 battery, the 300 nm Fe2‐NC demonstrated a peak power density of 0.618 mW cm−2, showcasing energy storage potential.