Preparation And Electrocatalytic Properties Of Platinum-nickel Heteromorphic Nanocatalysts

By rationally designing the size,morphology,composition and surface state of precious metal nanoparticles,it will maximize atomic utilization and will effectively increase the high activity and durability of the electrocatalyst.Therefore,a variety of effective strategies have been proposed,which can be divided into two main categories:(1)Adding another 3d transition metal(nickel,cobalt,copper,iron)can form a Pt alloy,thereby changing the availability of active surface sites(The overall effect)or the binding strength of the reactants,intermediates and products(electron and strain effect),and further reduce the amount of platinum,which can significantly improve the electrocatalytic properties of the alloy catalyst,(2)the synthesis of unique nanostructures and shapes Platinum-based particles,such as one-dimensional nanowires and nanorods,two-dimensional nanosheets,three-dimensional nanostructures,octahedrons,dodecahedrons,spines,and various nanoframes and nanocage.Such nanostructured crystals have an ultra-high specific surface area to provide more active sites,maximally increase the utilization of Pt atoms,and ultimately achieve an increase in catalyst activity and stability.Among various synthetic strategies,the morphology,surface structure and chemical composition of platinum-based nanocatalysts are the first considerations and are the most important in experimental research.Basic research and application-based research are milestones if they can effectively regulate these factors and make them work at their best.In this paper,we have explored and developed a simple and controllable solvothermal method to prepare various nanocrystalline catalysts,and can effectively and accurately control their morphology,surface structure and chemical composition.The experimental results are as follows:(1)Platinum-nickel(Pt-Ni)nanostructures with hyperbranched nanostructures were synthesized by one-pot solvothermal method.The catalysts consist of uniformly dispersed nanoparticles.In the electrochemical test results,Pt-Ni hyperbranched nanostructures as catalysts for oxygen reduction have higher electrocatalytic activity and stability than Pt-Ni nanoparticles and commercial Pt/C catalysts.Its excellent electrocatalytic performance is due to the fact that hyperbranched nanostructures often have many active sites,which maximizes the utilization of Pt atoms,and Pt-Ni hyperbranched nanostructures have a large number of tips,leading to a large number of negative charges at the tips,leading to the tip effect.(2)Cross-dumbbell platinum-nickel(Pt-Ni)nanostructure was prepared for the first time.It is composed of several nanosheets connected through the intermediate crystal nucleus to form an open three-dimensional structure.The results of electrochemical measurements show that the ternary nano-alloys exhibit excellent catalytic activity in alcohol oxidation and oxygen reduction reactions,as well as excellent CO toxicity resistance.The main reason is that the lattice mismatch strain in Pt-Ni bimetallic alloys will lead to the decrease of d-band centers,which will weaken the adsorption energy between Pt and O,thereby improving the electrocatalytic performance of ORR.On the other hand,the presence of Ni decreases the chemisorption of oxygen-containing substances such as CO on the catalyst surface,thus improving CO tolerance during MOR.