通过 MoS2 上的硫空位工程定向调节竞争性活性位点以实现固氮,Advanced Functional Materials

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通过 MoS2 上的硫空位工程定向调节竞争性活性位点以实现固氮
Advanced Functional Materials ( IF 18.5 ) Pub Date : 2023-05-12 , DOI: 10.1002/adfm.202302501
Hao Fei ₁ , Ruoqi Liu ₁ , Jian Wang ₂ , Ting Guo ₁ , Zhuangzhi Wu ₁ , Dezhi Wang ₁ , Fangyang Liu ₃

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_{电催化氮还原反应 (NRR) 为 NH 3}合成提供了一种环境友好且可持续的替代方案。然而，开发具有高活性和选择性的NRR电催化剂仍然是一个重大挑战。以密度泛函理论（DFT）计算为指导，并通过实验进一步验证，制备了具有良好控制的S空位的调制MoS _{2 （MoS}₂ -Vs）作为NRR的优异电催化剂，其中NRR的活性和选择性均得到提高很大程度上依赖于S-空位浓度。优化后的催化剂（MoS ₂ -7H）在合适的S空位浓度（17.5%）下具有优异的NRR活性（NH ₃产率：66.74 µg h ⁻¹ mg ⁻¹ at -0.6 V）和选择性（法拉第效率 (FE)：14.68% at -0.5 V）。进一步的机理研究表明，NRR 性能具有很强的浓度依赖性，因为其活性由于 S 空位增强的 N ₂吸附和降低的反应能垒而增强。同时，其选择性通过稳定增强的NRR活性同步提高，并通过限制H ₂解吸动力学反向抑制析氢反应，这使其与其他报道的有缺陷的MoS ₂基催化剂显着区别。

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Targeted Modulation of Competitive Active Sites toward Nitrogen Fixation via Sulfur Vacancy Engineering Over MoS2

Electrocatalytic nitrogen reduction reaction (NRR) offers an environmentally benign and sustainable alternative for NH₃ synthesis. However, developing NRR electrocatalysts with both high activity and selectivity remains a significant challenge. Guided by the density functional theory (DFT) calculations and further verified by the experiment, a modulated MoS₂ with well-controlled S vacancies (MoS₂-Vs) is prepared as an excellent electrocatalyst for NRR, where both the activity and selectivity of NRR mightily rely on the S-vacancy concentration. The optimized catalyst (MoS₂-7H) in a suitable S-vacancy concentration (17.5%) is empowered with an excellent NRR activity (NH₃ yield rate: 66.74 µg h⁻¹ mg⁻¹ at −0.6 V) and selectivity (Faradic efficiency (FE): 14.68% at −0.5 V). Further mechanistic study reveals that the NRR performance is powerfully concentration-dependent since its activity is enhanced due to the S-vacancy-strengthened N₂ adsorption and reduced reaction energy barrier. Simultaneously, its selectivity is synchronously improved by the steadily enhanced NRR activity and inversely suppressed hydrogen evolution reaction through limiting H₂ desorption kinetics, which sets it markedly apart from other reported defective MoS₂-based catalysts.

更新日期：2023-05-12

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