Electronic Structure Regulation Of Ruthenium-based Catalysts And Their Catalytic Application

As a critical step in hydrogen electrolysis of water,hydrogen evolution reaction（HER）has attracted wide research interest.However,the slow kinetics is a major obstacle to the large-scale implementation of hydroelectrolysis for hydrogen production,thus creating a strong need for a fast and stable catalyst to accelerate the reaction rate.Polyvinyl chloride（PVC）is one of the top five engineering plastics in the world,which is widely used in the construction industry and in the packaging,electrical and clothing industries.With the improvement of environmental protection requirements,the research and development of mercury-free catalyst has become the bottleneck technology of polyvinyl chloride industry.In catalytic reactions,the electronic structure of the catalyst plays an important role in the adsorption and activation of the reaction molecules.To realize the controllable electronic control of the catalyst by effective means is the key to improve its catalytic performance.In this paper,by constructing interface and ionic liquid ligand limited domain around Ru-based catalyst system,the intrinsic activity of Ru-based catalyst in electrocatalytic and thermal catalytic reactions can be improved,which provides useful reference for promoting its practical application（electrocatalytic hydrogen evolution and acetylene hydrochlorination）.The work of this paper is mainly divided into the following three parts:The first part of the work is to explore efficient Ru-based catalysts for electrocatalytic hydrogen evolution reaction（HER）.In this work,a defective B,N co-doped porous carbon is used as a carrier to load the metal Ru.On the one hand,the carrier promotes the high dispersion of Ru nanoparticles.On the other hand,electron transfer is established between the surface of B and N co-doped carbon and ultra-small Ru nanoparticles,and electrons are transferred from N atom to Ru atom,and then from Ru atom in reverse to B atom to give Ru moderate electron modification,which provides moderate H adsorption energy and low hydrolytic separation barrier.Benefit from particle size control and electronic regulation,the synthetic Ru based catalyst（Ru/（B-N）-PC）shows excellent HER performance in 1 M KOH(potential of 15 m V at current density of 10 m A cm^-2,Tafel slope of 22.6 m V dec^-1,superior stability over commercial Pt/C catalyst).It is also one of the most excellent HER catalysts in the literature.This work has successfully realized the interface regulation of B and N co-doped polar carbon surface for Ru-based catalysts,which is of great significance to promote the application of Ru-based catalysts in HER.The second part is to design and construct Ru Ni alloy with high density interfacial regulation and study the aspect of HER electrocatalysis.In the work,the carrier（Mo C@CN）is prepared by one-step pyrolysis,then the reasonable design and manufacture of Ru based catalyst（Ru/Ni/Mo C@CN）with dual active site is realized by equal volume co-maceration.Through various structural characterization,ruthenium and nickel species are present in both Ru Ni alloy ultrafine nanoparticles and Ru,Ni single atom forms.The electronic interaction between Ru and Ni in Ru/Ni/Mo C@CN will change the surface electronic state of the electrocatalyst,which optimizes the hydrogen adsorption free energy and promotes HER.In addition,Mo C quantum dots as carriers can accelerate charge transfer and protect Ru Ni nanoparticles from the electrolyte,thus providing impressive HER performance.Therefore,the Ru/Ni/Mo C@CN catalyst shows better HER activity under both acid and alkaline media.In particular,there is only an overpotential of 18 m V at a current density of 10 m A cm^-1 and a satisfactory long-term durability in alkaline media.This study provides a feasible approach for the rational design of efficient electrocatalysts with dual active sites.The third part uses ionic liquid electronic regulation to realize the efficient non-mercury metal catalytic application of Ru based catalyst in acetylene chlorination reaction.With the optimal Ru-NPC-Br-2 catalyst,the acetylene conversion remained above 97%within 50 h(T=170 ^oC,WHSV（C₂H₂）=2400 ml g^-1 h^-1 and V_HCl/V_C2H2=1.15).Furthermore,by reducing Ru load（0.5%Ru-NPC-Br-2）,the lifetime can reach 60 h under the condition that the acetylene conversion rate is above 98%(T=170 ^oC,WHSV（C₂H₂）=1600 ml g^-1 h^-1 and V_HCl/V_C2H2=1.15).The transmission electron microscope（TEM）,X-ray photoelectron spectroscopy（XPS）,thermal weight（TGA）methods show that the tetraethyllammonium bromide ion liquid can effectively promote the dispersion of Ru,inhibit the reduction of high Ru in the active site and the coke deposition in the acetylene chlorination reaction.This is of great significance to promote the study of non-mercury metal Ru-based catalysts.