Advances in Electrocatalytic N-2 Reduction-Strategies to Tackle the Selectivity Challenge

The industrial process used to reduce N-2 to NH3, typically the Haber-Bosch process, is energy-intensive and highly dependent on fossil fuels, a major source of greenhouse gas emissions causing undesirable climate change. Electrochemical reduction of N-2 to NH3 using renewable energy is one attractive approach to address this problem. A major challenge for electrochemical nitrogen reduction reaction (NRR) is low catalytic activity, accompanied by ultralow selectivity. Current studies have made some breakthroughs in Faradaic efficiency, with reasonable current density, while remaining far from satisfying the needs of commercial applications. This review discusses current strategies, focusing on the perspectives of catalyst design, cell configuration, electrolyte choice, etc., to tackle the selectivity challenge. In addition, rigorous control experiments to eliminate possible ammonia contamination and standard ammonia detection methods to ensure data accuracy are proposed, providing guidance for the field of NRR studies.