Preparation Of Nanoporous Ruthenium-Based Composites And Their HER Performance For Water Splitting

The increasing fossil fuel consumption has caused serious energy shortages and environmental pollution,and it is urgent to seek clean and renewable energy.Hydrogen energy has a high combustion heat value and no harmful emissions to the environment during combustion.Thus,it is considered to be one of the best energy sources to replace carbon based fuels.Electrocatalytic decomposition of water to produce hydrogen is one of the clean and sustainable methods for hydrogen production,and has attracted much attention due to its high purity.Hydrogen evolution reaction（Hydrogen Evolution Reaction,HER）is one of the semi reactions of electrocatalytic water decomposition,and its energy conversion efficiency is determined by the overpotential.Developing efficient electrocatalysts and reducing the overpotential required for the reaction are the keys to improving the efficiency of hydrogen production in HER.Precious metal Pt is the most active catalyst in the hydrogen evolution reaction of electrolytic water,but its reserves in nature are extremely low and expensive,making it unsuitable for large-scale use.Therefore,there is an urgent need to improve the atomic utilization rate of precious metals,reduce costs,and develop HER catalysts with the similar activity to that of commercial Pt/C.Metal Ru has similar chemical properties to Pt,and its hydrogen adsorption Gibbs free energy is also close to that of Pt in the hydrogen evolution theory.It has excellent HER activity,and its price is far lower than that of Pt-based materials.Therefore,it has broad application prospects in HER.Hence,it is of great significance to reasonably regulate the preparation of hydrogen evolution electrocatalysts from Ru-based nanomaterials.This thesis mainly focuses on the following aspects:1.Preparation of nanoporous Ru_xCu_97-xAl₃alloy and its catalytic efficiency by hydrogen evolution reactionRu_xC_u15-xAl₈₅(Ru₃Cu₁₂Al₈₅,Ru_5.2Cu_9.8Al₈₅and Ru_9.8Cu_5.2Al₈₅)ternary alloy strips with a width of 2 mm and a thickness of 40μm were prepared by melting a certain proportion of Ru,Cu,and Al alloy ingots in a vacuum electric arc furnace,and rotating and quenching the strip in an argon filled atmosphere.Corrosion of three different proportions of Ru_xCu_15-xAl₈₅ternary alloys in Na OH solution was conducted to obtain three different proportions of Ru_xCu_97-xAl₃alloy samples.Among them,Ru₆₄Cu₃₃Al₃has the most excellent electrocatalytic activity,favourable durability and good structural stability in hydrogen evolution reactions in alkaline electrolytes.In an alkaline solution,it only required an overvoltage of 20 mV to achieve a current density of 10 mA·cm^-2.After continuous testing in 1M KOH for 240000seconds（approximately 67 hours）,the current density of Ru₆₄Cu₃₃Al₃(40 mA·cm^-2)experienced only a slight attenuation,retaining 93.75%of its initial activity.The preparation strategy we proposed-dealloying has a high degree of versatility and flexibility,it can be extended to develop other simple and composite electrocatalysts for hydrogen extraction reactions.2.Preparation of nanoporous Ru_xCu_97-xAl₃P_xand its catalytic performance for hydrogen evolution reactionThree dried samples of Ru_xCu_97-xAl₃alloy and NaH₂PO₂ in different proportions prepared above were placed on the downstream and upstream sides of the tubular furnace,respectively.Subsequently,the above device is heated under an atmosphere filled with argon.We have successfully prepared Ru_xCu_97-xAl₃P_xnanoclusters with controllable morphology and different proportions,which are composed of rich porous structures and interconnected nanospheres.Benefiting from the synergy between rich active sites among various elements,as well as smooth material transport,the Ru₆₄Cu₃₃Al₃P_xelectrocatalyst has unique electrocatalytic properties for hydrogen evolution.Compared to other proportions of samples,the Ru₆₄Cu₃₃Al₃P_xelectrocatalyst produced exhibits optimal electrocatalytic performance and long-term sustainability of hydrogen evolution reactions in alkaline electrolytes.It only requires an overvoltage of-18 mV to achieve a current density of 10 mA·cm^-2,and after 100 hours of i-t testing,the current density of Ru₆₄Cu₃₃Al₃P_xremains basically at 40 mA·cm^-2,showing only a negligible decrease.In summary,based on the alloy Ru_xCu_15-xAl₈₅,we conducted component and morphology control to prepare nano porous Ru_xCu_97-xAl₃alloy hydrogen evolution electrocatalyst,and then prepared phosphide composite materials and it can be applied to electrocatalytic water resolution hydrogen reactions.In terms of alloys,we have adjusted the atomic ratios of Ru,Cu,and Al,and designed unique spherical nanoclusters with interconnected porous structures that provide outstanding electrocatalytic performance in hydrogen evolution reactions in alkaline electrolytes.In terms of phosphide composites,we have prepared hydrogen evolution electrocatalysts with excellent performance under alkaline conditions by using low-temperature vapor phase phosphating to control the atomic ratio of P to Ru,Cu,and Al.The above experiments can be used as a precondition for the development and breaking of high performance hydrogen precipitation electrocatalysts.