Effect of Amino Group of Organic Ligand in Cobalt-Based MOF Derived Materials on Electrocatalytic Oxidation of Urea

Electrocatalytic urea oxidation (UOR) has emerged as a promising alternative to the energy-intensive oxygen evolution reaction, offering dual benefits of energy-saving hydrogen production and environmental remediation of nitrogen-containing pollutants. In this work, we designed two metal-organic framework (MOF)-derived catalysts, Co-bpta-btc and Co-bpat-btc (bpta = 3,5-bis(4-pyridyl)-1,2,4-triazole; bpat = 3,5-bis(4-pyridyl)-4-amino-1,2,4-triazole; btc = 1,3,5-benzenetricarboxylate), to investigate the crucial role of the amino group in enhancing UOR performance. The derivative materials (Co-bpat-btc-700/NF and Co-bpta-btc-700/NF) are obtained through pyrolysis of Co-bpat-btc and Co-bpta-btc at 700 °C and loading on nickel foam (NF). The Co-bpat-btc-700/NF catalyst constructed from bpat ligands with amino group exhibited improved activity with a lower potential (1.358 V at 10 mA cm^–2) compared to its nonamino Co-bpta-btc-700/NF (1.377 V at 10 mA cm^–2), with the performance gap widening to 57 mV at 50 mA cm^–2. The main highlight of this work lies in the molecule-level regulation of the catalyst to optimize the electrocatalytic UOR activity. Specifically, it is reflected in the construction of two Co-MOFs using organic ligands with or without amino groups and similar structures. The urea conversion efficiency of the catalyst containing amino groups is higher (79.16% vs 66.78%). Systematic electrochemical characterization combined with product analysis revealed that the -NH₂ group not only facilitates charge transfer but also promotes urea-to-carbonate conversion, as evidenced by the higher CO₃^2– yield. These findings provided molecular-level insights into MOF structural design for efficient UOR catalysts and demonstrated a viable strategy for developing multifunctional electrocatalysts for energy and environmental applications. Notably, while this work demonstrates significant performance improvements, the specific action mechanism of amino groups still needs further investigation.