Research progress on electrochemical reduction for ammonia synthesis using cobalt-based catalysts

Electrocatalytic nitrate reduction to ammonia (NRA) offers a sustainable solution for simultaneously remediating wastewater and producing valuable ammonia; however, its practical application hinges on the development of efficient, stable, and cost-effective electrocatalysts. Among non-precious transition metals, cobalt-based catalysts are particularly promising due to their tunable d-electron configurations. Compared to iron or copper, cobalt species exhibit more favorable adsorption energies for key nitrogenous intermediates, resulting in superior NH 3 selectivity and Faraday efficiency (FE). This review systematically summarizes recent advances in cobalt-based single-atom catalysts, compounds, alloys, MOF-derived materials, oxides and molecular electrocatalysts for NRA. Furthermore, we analyze design strategies and performance modulation techniques across these material categories, identify key technical barriers to large-scale application, and outline future research directions. This work aims to provide a theoretical framework for designing high-performance cobalt-based NRA catalysts. This article reviews the mechanism of nitrate reduction reaction (NO 3 RR) achieved by cobalt-based catalysts, summarizes the research progress in the field of nitrate reduction in different cobalt-based catalytic systems, and discusses the design strategies and regulation ideas for optimizing the performance of cobalt-based materials. • Systematically reviews diverse cobalt-based electrocatalysts, ranging from single atoms (SACs) and alloys to MOFs and molecular complexes, establishing their specific structure-activity relationships for nitrate reduction. • Elucidates the unique advantages of cobalt, specifically its tunable 3d electron configuration and “chemical-electrochemical” loop mechanism, which balance intermediate adsorption and suppress HER better than Fe or Cu. • Analyzes advanced modification strategies, including microenvironmental control, defect engineering, and bimetallic synergy, to break adsorption energy scaling relations and optimize reaction kinetics. • Identifies critical engineering bottlenecks, such as stability in complex wastewater matrices and energy-intensive ammonia separation, providing a holistic roadmap for transitioning from lab-scale research to industrial application.