Ternary metal–organic framework of FeCoZn-ZIF as an efficient electrocatalyst for the oxygen evolution reaction

Abstract

Developing efficient, stable, and low-cost electrocatalysts for the oxygen evolution reaction (OER) is crucial for green hydrogen production via water electrolysis. In this work, a series of FeCoZn zeolitic imidazolate framework (ZIF) catalysts with varying metal ratios were successfully synthesized via a one-step hydrothermal method. Comprehensive characterization revealed that the as-prepared Fe₁Co₁Zn₂-ZIF maintained the typical rhombic dodecahedral morphology of ZIF-67, whereas the ternary metal doping induced a roughened surface decorated with nanoparticles, thereby increasing the specific surface area and the exposure of active sites. Electrochemical tests demonstrated that the catalyst with a Fe : Co : Zn molar ratio of 1 : 1 : 2 (Fe₁Co₁Zn₂-ZIF) exhibited optimal OER performance in 1 M KOH, requiring an overpotential of only 366 mV to achieve a current density of 10 mA cm⁻², comparable to that of commercial RuO₂. It also showed the lowest Tafel slope (78.7 mV dec⁻¹). Furthermore, this catalyst demonstrated superior charge transfer capability (R_ct = 12.52 Ω) and good stability, maintaining its catalytic activity for approximately 28 hours. The excellent performance is attributed to the synergistic effect among Fe, Co, and Zn, where Zn incorporation modulates metal dispersion, and Fe doping optimizes the electronic structure and facilitates charge transport. This study provides a new strategy for designing high-performance, cost-effective ternary metal-based OER electrocatalysts.