Amorphous Sn/Crystalline SnS₂ Nanosheets via In Situ Electrochemical Reduction Methodology for Highly Efficient Ambient N₂ Fixation

Abstract

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.

Exploration and Investigation of Periodic Elements for Electrocatalytic Nitrogen Reduction

“…Tin sulfides were also scrutinized for NRR in the form of amorphous Sn/crystalline SnS 2 (Sn/SnS 2 ). [ 272 ] It was synthesized by hydrothermal process followed by electrochemical reduction method. It exhibited an efficiency of 6.5% at −0.7 V when tested in 0.1 m phosphate buffer solution (PBS).…”

Recent Advances in the Application of Structural‐Phase Engineering Strategies in Electrochemical Nitrogen Reduction Reaction

“…In addition to amorphous oxides, the amorphous metal Sn can limit surface electron accessibility, resulting in suppression of the HER process, and can also be used as an NRR electrocatalyst. Li et al [58] used amorphous Sn/crystalline SnS 2 as the electrocatalyst in 0.1 m NaOH; the yield of NH 3 was 23.8 µg h −1 mg cat. −1 at −0.8 V versus RHE, and the Faraday efficiency was 6.5% at −0.7 V versus RHE.…”

“…[ 24 ] As of now, there have been the following two types of amorphous electrocatalysts for NRR in research reports: amorphous Bi 4 V 2 O 11 /CeO 2 [ 57 ] and amorphous Sn/crystalline SnS 2 . [ 58 ] The amorphous Bi 4 V 2 O 11 contains significant defects, which play a role as active sites. The CeO 2 not only serves as a trigger to induce the amorphous structure but also establishes band alignment with Bi 4 V 2 O 11 , resulting in rapid interfacial charge transfer.…”

Recent Advances in Noble‐Metal‐Free Catalysts for Electrocatalytic Synthesis of Ammonia under Ambient Conditions

“…[66] Chu et al synthesized the SnO 2 quantum dots (QDs) supported on reduced graphene oxide (RGO) with a high NH 3 yield of 25.6 μg h À 1 mg cat À 1 and a FE of 7.1% at À 0.5 V. The SnO 2 /RGO could offer abundant sites for effective N 2 adsorption and lower the energy barrier. [67] Moreover, the optimized Sn/SnS 2 catalyst could reach an NH 3 yield of 23.8 μg h À 1 mg cat À 1 at À 0.8 V and a high FE of 6.5% at À 0.7 V. [68] To date, only one work has reported an Antimony-Based catalyst, PC/Sb/SbPO 4 (PC, phosphorus-doped carbon), toward NRR. [69]…”