Highly Efficient Bi–Fe-Doped Carbon Electrocatalyst with ZIF8 Structure for Alkaline OER Water Splitting

In this work, bimetallic Bi–Fe/N-doped carbon (Bi–Fe/NC) catalysts derived from zeolitic imidazolate framework-8 (ZIF8) as an oxygen evolution reaction (OER) electrocatalyst were fabricated by a solvothermal process, followed by pyrolysis. The effect of pyrolysis temperature, Bi-to-Fe ratio, and metal-to-ZIF8 ratio on catalytic performance toward OER was investigated. X-ray diffractogram revealed that samples pyrolyzed at different temperatures resulted in different oxides. The sample pyrolyzed at 900 °C produced γ-Fe2O3, which exhibited good electrocatalytic performance in 1 M KOH, with an overpotential and a Tafel slope of 397.48 mV at 10 mA cm–2 and 80.61 mV dec–1, respectively. Its superior performance compared to samples with lower pyrolysis temperatures could be attributed to its enhanced conductivity and electrochemically active surface area (ECSA). The sample with a 2:8 Bi-to-Fe ratio exhibited the best electrocatalytic performance, which was influenced by structural defects and phase composition. When the metal loading ratio was varied, a metal loading ratio of 0.05 achieved an optimal balance of metal dispersion and defect density, thereby enhancing electronic conductivity and ECSA. This work highlights the potential of Bi–Fe doped ZIF-derived carbon as an electrocatalyst for oxygen evolution.