Controllable Synthesis Of Metal Nanomaterials For Nitrogen Electroreduction Reaction

Ammonia(NH3)plays a vital role in modern industrial and agricultural production.At present,the Haber-Bosch method is still the most efficient industrial method for the synthesis of NH3,but it has the disadvantages of high energy consumption and low environmental protection.As one strategy for the synthesis of NH3,the nitrogen electroreduction reaction(NRR)has great potential because it has the advantages of being driven by renewable energy and abundant raw materials.This has great practical significance for the sustainable development of energy and green chemistry.In addition,the metal nanomaterial with d-orbital can easily supply electrons to the N=N triple bond orbital,enhance N2 adsorption and weaken the stability of the N=N triple bond,thereby achieving effective N2 activation and conversion.However,there is still a great challenge to carry out effective controllable synthesis.Therefore,it is necessary to rationally design and optimize metal nanomaterials to improve the NRR activity,selectivity and stability.In this paper,we introduce the controlled synthesis of PdCu nanoparticles with different crystal-phase structures,Pt3Fe nanocrystals with adjustable surface structure,and MoFe nanobelts with different components,and explore their NRR performance.The main contents are summarized as follows:Chapter 1.This part briefly introduces the NRR research progress,reaction mechanism,reaction path,strategies of catalyst design,and clarifies the basis and research content of this paper.Chapter 2.Most of reported NRR electrocatalysts are disordered phase structure.On the contrary,ordered phase structure with ordered atomic arrangement,strong electron interaction,and high mixing enthalpy can regulate electronic structure of catalyst to enhance catalytic performance.Therefore,we successfully transform disordered phase structure PdCu catalyst into ordered phase structure PdCu catalyst by calcination treatment.Compared with disordered phase structure PdCu catalyst,ordered phase structure PdCu catalyst exhibits strong N2 binding ability and low reaction energy barrier during the NRR process,hence it has more excellent activity and stability.Chapter 3.Most of reported NRR catalysts are nanoparticles,and the exposed surface structure is relatively complicated.In contrast,nanocrystals with distinct surface structure can be adopted as ideal model electrocatalysts for fundamentally understanding the relationship between surface structure and catalytic activity.Therefore,we prepared Pt3Fe nanocrystals with different surface structures.Among them,Pt3Fe nanowires with high-index facets show slow hydrogen evolution reaction kinetics and strong N2 binding ability during the NRR process,ensuring that their activity is better than that of Pt3Fe nanocubes with {200} facets and Pt3Fe nanorods with {111} facets.Chapter 4.Most of reported NRR catalysts with excellent activity are precious metal catalysts,but the high cost problem severely limits their wide application.In recent years,the research focus has gradually shifted to non-noble metal catalysts.Inspired by the biological nitrogen fixation catalyzed by MoFe nitrogenase,Mo and Fe components have excellent N2 binding ability.In addition,in order to increase the number of active sites,it is necessary to construct novel structure with high specific surface area.Therefore,we prepared Mo3Fe nanobelts catalyst with high specific surface area and numerous active sites,which show excellent NRR activity and stability.