Amorphous Sn/Crystalline SnS₂ Nanosheets via In Situ Electrochemical Reduction Methodology for Highly Efficient...

Electrochemical nitrogen reduction reaction (NRR) as a new strategy for synthesizing ammonia has attracted ever-growing attention, due to its renewability, flexibility, and sustainability. However, the lack of efficient electrocatalysts has hampered the development of such reactions. Herein, a series of amorphous Sn/crystalline SnS₂ (Sn/SnS₂ ) nanosheets by an L-cysteine-based hydrothermal process, followed by in situ electrochemical reduction, are synthesized. The amount of reduced amorphous Sn can be adjusted by selecting electrolytes with different pH values. The optimized Sn/SnS₂ catalyst can achieve a high ammonia yield of 23.8 µg h^-1 mg^-1 , outperforming most reported noble-metal NRR electrocatalysts. According to the electrochemical tests, the conversion of SnS₂ to an amorphous Sn phase leads to the substantial increase of its catalytic activity, while the amorphous Sn is identified as the active phase. These results provide a guideline for a rational design of low-cost and highly active Sn-based catalysts thus paving a wider path for NRR.