Symmetry-breaking structure electrocatalysts for nitrate reduction to ammonia

Ammonia (NH₃) is a pivotal component for the majority of fertilizers, chemicals, and pharmaceuticals. Its conventional production through the Haber–Bosch process is highly energy-intensive and significantly contributes to CO₂ emissions, thereby exacerbating global warming. In parallel, the overuse of agricultural fertilizers and the inadequate industrial wastewater management cause the heavy nitrate (NO₃⁻) pollution which poses huge environmental and health hazards to human beings. In an effort to address these challenges, scientists have been exploring more sustainable methods of ammonia synthesis and strategies to mitigate nitrate pollution. Among these, the electrocatalytic reduction of nitrates to ammonia/ammonium (NO₃RR) presents a promising solution. This innovative approach not only reduces the environmental footprint of ammonia production by operating under ambient conditions but also contributes to the purification of water bodies by lowering nitrate levels. This review intricately explores the complexities involved in the electrocatalytic reduction of nitrates to ammonia, shedding light on the nuanced mechanisms underlying the process and elucidating the importance of symmetry-breaking structures. It particularly underscores the pivotal role played by various symmetry-breaking structures in catalysts, which serve to disrupt and invigorate the reaction environment, thus enhancing the efficiency of the electrocatalytic process. In culmination, we offer a comprehensive summary of the advancements in the development of catalysts featuring symmetry-breaking structures, providing insights and forward-looking recommendations for the future engineering of broadly applicable symmetry-breaking structure catalysts.