Synthesis Of Ruthenium-based Nano-alloys And Their Application For Hydrogen Evolution Reaction

Hydrogen energy is an ideal energy carrier owing to its high energy density,clean and pollution-free features.Among the available hydrogen production methods,electrochemical water splitting provides an effective strategy to produce eco-friendly clean hydrogen.Developing the efficient and stable electrocatalyst to promote hydrogen evolution reaction（HER）is the key to realize massive hydrogen production by electrochemical water splitting.By far platinum（Pt）-based catalysts are still considered to be the efficient catalysts for HER,but their practical application in hydrogen production by electrolysis of water is seriously hindered by the scarcity and high cost.As a cheaper alternative to Pt,Ru possesses similar bond strength with hydrogen,which endows Ru the high HER catalytic activity.Hence,developing Ru-based nanomaterials as remarkable HER catalysts has received a lot of attentions in recent years.In this paper,composition engineering and morphology engineering were adopted to improve the HER performance of Ru-based nanomaterials,involving transition metal doping,carbon layer modification and tip-like local electric field enhancement.The origins of enhanced HER performance were also explored by combining with experiments and theoretical simulation.The research consists of the following parts:1.Carbon layer confined RuCr nanoparticles（RuCr@C）were prepared by using a simple molten salt-assisted synthesis method.As expressed by electrochemical measurements,the Ru Cr@C possesses excellent HER performance in 1.0 M KOH solution.It exhibits an overpotential of only 19 m V at a current density of 10 m A cm^-2,and a high turnover frequency value up to 4.25 H ₂ s^-1 under an overpotential of50 m V.With evidence from theoretical simulations,incorporating oxophilic Cr can significantly reduce the energy barrier of water dissociation,while the carbon layer further optimizes the adsorption strength of H^*on Ru site.These two aspects play a synergistic effect in the critical steps of alkaline HER,endowing Ru Cr@C excellent HER activity2.Nano-cone assembled Ru₃Ni alloy nanomaterials were synthesized by a simple solvothermal method.As demonstrated by measurements,the Ru₃Ni/C shows good HER performance with a low overpotential of 16 m V at 10 m A cm^-2,especially a ultralow overpotential of 168 m V at 1000 m A cm^-2 in 1.0 M KOH solution.Moreover,the Ru₃Ni/C can keep stable over 1800 h.In anion exchange membrane（AEM）based electrolyzer,the Ru₃Ni/C displays high hydrogen yield rate and ultrahigh stability of450 h under a current density of 1000 m A cm^-2,which shows the great potentials for commercial application.Combining experimental studies and theoretical calculations,the origins of the excellent HER performance over Ru₃Ni/C were investigated.On the one hand,the surface adsorption of^*OH on the catalyst is enhanced with the presence of Ni,so as to promote water dissociation and improve the HER catalytic activity.On the other hand,the nano-cone structure possesses tip-like enhanced local electric field effect,which could increase the K⁺ion concentration around the catalyst surface.The water molecules could be more polarized by concentrated K⁺,which can stretch the H-OH bond of H₂O and reduce the energy barrier for water dissociation.With benefits from those aspects,the Ru₃Ni/C possesses outstanding HER performance.