Study On The Preparation And Catalytic Performance Of Nickel-based Low-load Noble Metal Composite Materials

The development of highly active and durable methanol electrooxidation reaction?MOR?electrocatalysts for direct methanol fuel cells?DMFCs?is crucial to achieve their practical application in future energy storage and conversion.Direct methanol fuel cell?DMFC?has the advantages of rich source of raw materials,convenient carrying,high volumetric energy density,low temperature startup,clean and environmental protection,etc.,making it a broad application prospect as a power source for electric vehicles and portable computers and other equipment.The development of electrocatalytic methanol oxidation catalysts with high activity and durability is crucial for the practical application of direct methanol fuel cells for their future energy storage and conversion.Up to now,Pt and Pt-based materials are the most active MOR catalysts.First,we demonstrate that a nickel supported Pt-decorated electrode with an ultralow mass loading featuring Ni-Pt hybrid nanoparticles growing on self-reconstructed porous nickel frameworks was synthesized via a facile electrochemical activation process in an acidic solution,and its application in electrocatalysis was explored.Combined with characterization analysis,the formation mechanism of Pt/p-Ni was studied,and then the electrocatalytic performance of Pt/p-Ni was systematically studied on the activation temperature,the potential range of activation,the continuous activation period and the pH of the activation solution.The activation approach results in surface rearrangement of Ni substrate to form nanoporous skeletons and highly dispersed Ni-Pt hybrid nanoparticles with a mean size of 4.34 nm grown on the nano-ligaments of the Ni porous skeletons,with a Pt loading of 1.50?g cm^-2.The porous skeletons decorated with nano-dispersion of Pt significantly increase the surface active sites and,therefore,yield a superior catalytic activity.Secondly,The self-supported Pt-decorated porous nickel frameworks?Pt/p-Ni?was systematically studied in the alkaline medium for electrocatalytic performance,throughcyclicvoltammetry,electrochemicalimpedancespectroscopy,chronoamperometry,etc.The Pt/p-Ni exhibit 3.65-fold higher activity for catalyzing the MOR than that of commercial Pt/C with the same Pt loading under alkaline media.Experiments coupled with density-functional theory?DFT?calculations suggest the existence of a strong electronic interaction with charge transfer from the Ni skeletons to Pt atoms at the superface of the Pt/p-Ni.This electronic structure modification leads to efficiently weaken the adsorption of CO on the catalyst surface and alleviate the CO_ads poisoning of the active sites,resulting in remarkably enhanced MOR activity and durability.Therefore,the electrode can be used as a highly active DMFC anode catalyst.Finally,we have prepared a nano-porous nickel-palladium composite catalyst?Pd/Ni?containingultra-low-loadednoblemetalPdbyasimple displacement-deposition method in eutectic ionic liquids,and its application in electrocatalysis was explored.The prepared samples were characterized by SEM and ICP-MS,and the electrocatalytic oxidation activity and stability of Pd/Ni were investigated by cyclic voltammetry and chronoamperometry.The results show that the Pd/Ni electrode surface was found to consist of densely mixed nanoparticles with an average particle size of approximately 100 nm,and the Pd loading is 50?g cm^-2;Compared to other Pd/Ni catalysts reported in other literatures that catalyze methanol oxidation activity in alkaline media,Pd/Ni electrodes prepared by displacement methods in eutectic ionic liquids show more excellent catalytic activity and stability.