New Type of Copper–iron Metal-Organic Framework Composited with Carbon Nanotubes for Enhanced Oxygen Evolution Reaction

To reveal the oxygen evolution reaction (OER) catalytic performance and structure-activity relationship of copper-iron-based metal-organic frameworks (MOFs) at the molecular level, new types of Cu-Fe MOF based materials, Cu2Fe/CNT and {CuFe2}n/CNT (CNT: carbon nanotube), were synthesized and studied. The results showed that the two materials exhibited different catalytic activities, with the former showing lower activity (Overpotential at the current density of 10 mA cm-2: 110 = 450 mV, Tafel slope: 92.4 mV dec-1) and the latter showing much higher activity (110 = 370 mV, Tafel slope: 64.8 mV dec-1). Further analysis revealed that the performance difference was due to ligand rearrangement between metals in Cu2Fe/CNT, which affected the exposure of active metal sites. Meanwhile, the unique three-dimensional MOF structure of {CuFe2}n/CNT significantly increased the electrochemical surface area (ECSA), enhancing the electrochemical performance. This study demonstrates how the intricate ligand rearrangement effects in non-precious metal catalysts can greatly influence their performance. Understanding and rationally tuning these coordination interactions is crucial for designing high-performance non-noble metal electrocatalysts.