Preparation And Electrochemical Performance Of Noble Metal-Based Composite Nanomaterials

Facing the increasingly serious energy crisis and environmental problems,it is necessaryto develop the new green,environment-compatible,and efficient energy and technology achievements.On the one hand,clean and renewable energy sources should be expanded.On the other hand,it is necessary to develop new energy storage devices with high efficiency and low cost for developing new energy technologies.Hydrogen has the advantages of environment-compatible,easy to store and high energy density,which makes it the most promising clean energy.On the other hand,the supercapacitor cause more attention for its large power density,high charging speed,long cycle life and environmental compatibility.In this paper,electrolytic catalysts for water splitting and supercapacitor electrode materials were explored,which were listed as follows:(1)Electrolysis of water is an effective way,abundant raw materials and high energy conversion,of obtaining the hydrogen.For industrial electrolytic hydrogen production,the high cost of catalysts restricts its development.Therefore,the design of electrolytic catalysts with high activity and low cost is the current focusof researches.Ir nanoparticles were in-situ grown on the surface of the SiNWs by the reduction of Si-H bonds in the hydrothermal reaction.The SiNWs serve as both the supports and the co-catalyst during the HER reaction.The 17.7 wt%Ir@SiNWs catalyst has a low overpotential and high current density(j0= 1.299 mA cm-2)together with a low Tafel slope of 20 mV dec-1.Further more,the real exchange current density of the 17.7 wt%Ir@SiNWs is 0.0486 mA cm-2 which is large than 0.0465 mA cm-2 for commercial 20 wt%Pt/C.In addition,the stability of 17.7 wt%Ir@SiNWs is excellent together with a low activation energy.(2)A simple one-pot hydrothermal method was used to in-situ grow iridium nanoparticles on reduced graphene oxide(Ir@rGO).The Ir@rGO has a high catalytic activity for both HER and OER.Both for HER and OER,the overpotential of 25.6%Ir@rGO is lower than commercial Pt/C.The one set potential of 25.6%Ir@rGO for OER is about 1.45V and the overpotential for HER is nearly 0.The 25.6%Ir@rGO has the optimalcatalytic activity for overall water splitting and the potential is only 1.54 V at the water splitting activity of 10 mA cm-2.Forethemore,the stability of 25.6%Ir@rGO for overall water splitting is quite excellent.(3)The Ag/NiO nanocomposite(ANC)was obtainedthrough the AgNiO2 precursor after an activation process,which exhibits aremarkable electrochemical performance.It is obviously noticed that ANC shows high specific capacities of 1166 and 512 C g-1 at current densities of 2 and 32 A g-1,respectively.The decay in the specific capacity is only 10%loss after 2000 cycles,revealing the excellent cycling stability of ANC.