Synthesis Of Cage-shaped Hollow Carbon Spheres Loaded Ruthenium-based Metal And Their Application In Hydrogen Evolution Reaction

With the dramatic increase in environmental pollution and energy crisis,humans are increasingly demanding clean renewable energy.Hydrogen is a clean fuel with the advantages of high combustion calorific value,non-polluting combustion products,and extensive resources.It is an ideal energy carrier.Hydrogen production by electrolysis of water is an effective method for producing hydrogen.It has the advantages of high hydrogen production efficiency and no pollution.However,it is currently facing problems such as high energy consumption and large investment costs.The hydrogen evolution catalyst can effectively reduce the hydrogen evolution overpotential.However,the traditional Pt-based catalysts are expensive,which limits the large-scale application of hydrogen production by electrolysis of water.Therefore,it is very important to develop efficient and inexpensive hydrogen evolution catalysts.Ru is a noble metal.It has a hydrogen binding energy close to that of Pt,and has high hydrogen evolution catalytic activity,but its price is only 1/5 of Pt.If some problems such as easy agglomeration and poor conductivity can be well properly solved,Ru metal will be an ideal noble metal substitute for Pt-based catalysts.The carbon-based carrier can increase conductivity,promote electron transfer in the catalytic process,and increase catalytic activity.Hollow carbon spheres are a kind of carbon-based material with special structure.They have the advantages of large specific surface area,stable structure,controllable size,and convenient introduction of functional groups.They are carbon-based carriers with excellent performance.The mesopores on the carbon material can provide channels for ion transmission,accelerate the catalytic reaction,and enhance the catalyst activity.Based on this,this work uses hollow carbon spheres with large mesopores as a carrier to synthesize two kinds of catalysts named Ru@DHPCS and Ru Ni@HPCS for the electrolysis of water to produce hydrogen,and explore the effects of structure and composition on catalytic activity.Main contents are listed as follows:（1）Using PS microspheres as the template and polydopamine as the carbon precursor,double-shell hollow microspheres were successfully synthesized.By etching away the titanium oxide between the two layers of polymer,large mesopores were successfully introduced into the microspheres.Finally,cage-shaped double-shelled hollow carbon spheres/Ru catalyst（Ru@DHPCS）were successfully synthesized by using Ru Cl₃·x H2O as the raw material through hydrothermal reaction.Through SEM,TEM and other structural characterization,we found that the synthesized microspheres have uniform structure,obvious pores,and the loaded Ru nanoparticles are uniform without agglomeration.Through x-ray photoelectron spectroscopy analysis,it is found that nitrogen can be successfully introduced in the carbon spheres using polydopamine as the carbon precursor,which will effectively improve the surface wettability of the carbon spheres and increase its conductivity.By exploring the influence of different amount of Ru loadings on the catalytic performance,we synthesized catalysts with different Ru loadings by adding different amount of Ru Cl₃·x H2O,and finally found that the catalyst has the best hydrogen evolution catalytic activity when 2.5 mg Ru Cl₃ is added to 10mg microspheres.When the current density reach 10 m A cm^-2,the aquired overpotential is 19m V,79m V,and the Tafel slope is 58.7 m V dec^-1,64.2 m V dec^-1 in the 1 M KOH,0.5 M H₂SO₄solution.respectively,it shows excellent hydrogen evolution activity.（2）Using carboxylated polystyrene microspheres（CPS）as templates,silica particles as a pore-forming agent,and polydopamine as a carbon precursor.Then,cage-shaped hollow carbon spheres/Ru Ni catalyst（Ru Ni@HPCS）were successfully synthesized by using Ru Cl₃·x H2O and Ni（NO₃）₂·6H2O as the raw material of alloy particles,cage-shaped hollow carbon microspheres as carrier through hydrothermal reaction.Through SEM,TEM and other structural characterization,we find that the synthesized microspheres have uniform structure,obvious pores,and the supported Ru Ni alloy nanoparticles are uniform and non-agglomerated.Ru Ni@HPCS exhibits excellent catalytic activity in both acidic and alkaline environments,and the current density can reach 10 m A cm^-2 in acidic and alkaline environments.The overpotentials of 10 m A cm^-2 are 63m V,16m V,and the Tafel slopes are 46.2 m V dec^-1,46.1 m V dec^-1,respectively.The performance of the catalyst in alkaline solution is even better than commercial Pt/C,accompanying with excellent stability.