Study On PtNi Nanostructured Electrocatalysts For Hydrogen Evolution And Methanol Oxidation Reactions

In today's international society,fossil fuels like oil,coal,and natural gas are still the main sources of energy,which are in an urgent situation of running out.Besides,the burning of these fossil fuels can lead to the discharging of sulfide,nitrogen oxides and volatile organic gases to the atmosphere,causing various environmental problems.With the fossil energy reserves dwindling and increasingly serious environmental pollution,we should find new energy to replace the main energy and develop more reasonable,clean and efficient methods to take advantage of it.Fuel cells and water splitting as the key energy candidates to the future hydrogen economy can directly convert the chemical energy of fuels into electrical energy,thus has attracted widespread attention in both industry and fundamental studies,regarded as the first generation technology in 21st century.The point of fuel cells is the design of efficient electrocatalysts.Up till now,among all the catalysts,Pt-based materials has the largest potential.Unfortunately,the high cost and low stability during the reaction are strongly blocking their commercial application.Therefore,many researchers are engaging in synthesizing electrocatalysts with a higher utilization rate of Pt and an enhanced stability.In this thesis,a simple coreduction process involving glycine and PVP as both reductants and capping agents was used to produce PtNi concave nanocubes?CNCs?bounded by high-indexed facets.The as-prepared PtNi CNCs were then distributed evenly in n-butyl amine for 3 days to combine adequately with OH.As expected,the obtained PtNi-OH?-O?CNCs exhibited both enhanced activity and stability in methanol oxidation reaction?MOR?under basic condition.Because the OH group on the surface of the catalyst can not only participate in the oxidation of adsorbed CO,but also promote the dissolution of water molecules,which produces more adsorbed OH to facilitate the removal of CO.Later,in order to improve the catalytic properties of Pt-based catalysts,we synthesized ultrathin Ni?OH?₂ nanosheets and loaded PtNi CNCs on them via a hydrothermal method to introduce more OH to the material.During the combination,the smooth surface of PtNi CNCs turned to a rough one,providing more active sites.The resultant products are named PtNi/Ni?OH?₂ and used in hydrogen evolution reaction?HER?and MOR under alkaline condition.In HER,Ni?OH?₂ with defects can help cleave the HO-H binding,leading to a higher activity and stability.In MOR,the removal of adsorbed CO on the surface of PtNi/Ni?OH?₂ are accelerated,causing a better activity and stability.