Application Of Electrocatalytically Active Transition Metal Nanomaterials In Nitrogen Reduction Reaction

NH₃ is one of the most important fundamental chemicals in the world and has great applications in industry and agriculture.With the increasing demand for NH₃,it is imperative to develop alternative methodology for energy-intensive Haber-Bosch process.Electrocatalytic nitrogen reduction reaction?NRR?for NH₃ synthesis is a promising approach.However,identifying the high activity,stability and excellent selectivity of electrocatalysts for N₂ adsorption and activation remains a challenge.To meet these challenges,we applied defect engineering and interface engineering to design electrocatalysts to boost the efficiency of NH₃ synthesis:1.As an important transition metal oxide,WO₃ could realize the activation of N?N triple bond and direct photocatalytic synthesis of nitrate.Inspired by this,we applied defect engineering to design WO₃ nanosheets rich in oxygen vacancies to achieve electrocatalytic N2 reduction to NH3 under ambient conditions.Such WO3 nanosheets rich in oxygen vacancies?R-WO₃?achieve a large NH₃ yield of 17.28?g h^-1 mg_cat.^-1and a high Faradaic efficiency of 7.0%in 0.1 M HCl,much superior to the WO₃ nanosheets deficient in oxygen vacancies.Remarkably,R-WO₃ NSs also show excellent electrochemical and structure stability.2.Layered transition metal sulfides have a large specific surface area and excellent electronic properties,which are very beneficial for electrocatalytic applications.We used R-WO₃ nanosheets as precursors to prepare defect-rich WS₂ nanosheets?R-WS₂?by vacuum sealed-tube vulcanization method.This R-WS₂ achieve a high of 12.1%Faradaic efficiency with a NH₃ generation rate of 16.375?g h^–1 mg_cat.^–1,under neutral conditions?0.1 M Na₂SO₄?,this performance outperform most NRR electrocatalysts.3.In nature,Mn can significantly promote the catalytic activity of nitrogenase in photosynthetic bacteria Rhodospirillum rubrum extracts.MnO₂ shows lots of merits such as low cost,low toxicity and friendly interfacial properties with carbon materials,and intrinsically possesses a poor hydrogen evolution reaction activity.However,the low conductivity of MnO₂ is detrimental to electrocataltic applications.Previous researchs show that interface engineering is an effective strategy to optimize catalytic performance.To this end,we designed MnO₂-Ti₃C₂T_x nanohybrids using interface engineering.MnO₂-Ti₃C₂T_x nanohybrids can be used as an efficient and stable non-precious metal catalyst for ambient N₂-to-NH₃ conversion due to the the fascinating properties at the interface and synergism of the constituent components.In 0.1 M HCl,MnO₂-Ti₃C₂T_x nanohybrids achieve a high NH₃ yield of 34.12?g h^–1 mg_cat.^–1and a high Faradaic efficiency of 11.39%,comparing favorably to the behaviours of MnO₂ and Ti₃C₂T_x.Density functional theory calculations further reveal that the unsaturated surface Mn atoms act as active sites to adsorb and activate the inert N₂ molecules for the NRR process and the rate-determining step is the first hydrogenation process.