Tuning the organic ligands to optimize the nitrogen reduction performance of Co(ii) or Ni(ii)-based MOFs†

The electrocatalytic nitrogen reduction to ammonia reaction (eNRR) can use clean energy and catalyst materials to convert N₂ to NH₃ under relatively mild conditions, but how to design and synthesize electrocatalysts has been the focus of eNRR research. Metal–organic frameworks (MOFs) are a class of crystalline porous materials with a high specific surface area, high porosity and a designable structure, and show great potential as new electrocatalysts. Designing and synthesizing MOFs with high stability and high conductivity, and optimizing the adsorption energy of MOFs with nitrogen and intermediates are the key to improve the electrocatalytic performance. Hence, five Co-MOFs with a similar structure were designed to investigate the effect of small changes in the organic ligand structure on nitrogen reduction performance. Among them, the Co-MOF based on the thiazole ligand shows the best eNRR performance, with the highest NH₃ yield (51.30 μg h⁻¹ mg_cat⁻¹) and Faraday efficiency (29.2%) at −0.4 V vs. RHE. This study can provide theoretical guidance for the design and development of high-performance eNRR electrocatalysts in the future.