Electrochemical nitrate reduction to ammonia by non-noble metal single-atom catalysts: bridging waste remediation and sustainable hydrogen storage

Review article, 2026

Ammonia plays a pivotal role in agriculture and industry, while being increasingly viewed as a carbon-free hydrogen carrier. Over the past decade, electrochemical nitrate reduction to ammonia has emerged as a promising green route, bridging waste remediation and effective hydrogen storage. In this context, non-noble metal single-atom catalysts (SACs) are particularly attractive due to their tunable electronic structure and high reaction selectivity. This review provides a timely and comprehensive overview of electrochemical nitrate reduction to ammonia by non-noble metal SACs. In this review, the principles and reactor configurations for electrochemical nitrate reduction are examined and then the synthesis strategies and characterization techniques for non-noble metal SACs are critically summarized. Recent advances in utilizing non-noble metal single-atom catalysts for electrochemical nitrate reduction to ammonia are systematically assessed in terms of NH3 yield, Faraday efficiency, selectivity, and underlying mechanisms. Finally, the persistent challenges and future perspectives are discussed, with the aim of guiding the rational design of non-noble metal single-atom catalysts towards highly efficient electrochemical nitrate reduction to ammonia.