Modifying Microenvironment in Van der Waals Gap by Cu/N Co‐Doping Strategy for Highly Efficient Nitrite Reduction to Ammonia

Electroreduction of nitrite to ammonia has significant promise for economical NH₃ electrosynthesis and wastewater treatment. Herein, sulfur vacancies rich Cu─N co-doped SnS₂ nanosheet is designed as a highly active and durable NO₂RR catalyst. Benefiting from the Cu─N co-doped strategy, Cu/N-SnS_2-x achieves the highest NH₃ yield rate of 18.15mg h^-1 mg_cat ^-1 at -0.935 V (vs RHE) and excellent Faradaic Efficiency of 95.73% at -0.835 V (vs RHE). In situ FT-IR and in situ XPS proves that Cu/N-SnS_2-x has a greater capacity for atomic hydrogen generation, which facilitates the conversion of nitrite to ammonia and maintains excellent structural stability during the NO₂RR process. Theoretical calculations reveal that the introduced sulfur vacancies effectively expose the metal atoms inside SnS₂ and make them adsorb nitrite efficiently, which effectively accelerates the transformation of nitrite to ammonia. Besides, the introduced Cu and N can form a new electronic structure, which induces Cu in an electron-deficient state promotes the adsorption of reaction intermediates on Cu, and reduces the reaction energy barrier for nitrite reduction on the Cu/N-SnS_2-x surface. The current exploration presents fresh prospects for the rational development of an effective electrocatalyst for synthesizing ammonia from nitrite.