Controllable Synthesis Of Platinum-Based Nano Electro-Catalysts And Their Catalytic Performance

The search for clean and efficient energy conversion systems or new energy resources have become a must be solved issue about sustainable development.because of a serious energy crisis and the global environmental pollutions that have arisen from the excessive consumption of fossil fuels.Therefore,high-efficiency energy conversion systems with almost no environmental pollution,such as,metal-air batteries and Fuel Cells,as the most promising practical portable electric devices and electrical vehicles have aroused intense research interest over the past several decades.Proton exchange membrane fuel cells(PEMFC)have received wide attention as nextgeneration energy conversion technologies,with zero emissions,high efficiency and fast startup at low temperatures.At present,Pt-based catalysts are still used as eletrocatlasyts most widely in Fuel Cells.However,the high cost and low stability limit its large-scale commercial applications.Therefore,the development of new catalysts with low cost,high activity and stability,remains a great challenge.In view of the above problems,we selected a relatively low-cost transition element and controlled the synthesis of a series of Pt-based alloy nanocatalytic materials by optimizing the reaction conditions.Futhermore,their electrocatalytic performance toword methanol oxidation reaction(MOR)and oxygen reduction reaction(ORR)which used as the model reaction have been studied systematically.The research contents mainly include: controllable synthesis of carbon-supported zero-dimensional Pt-M nanocrystalline,ultrathin one-dimensional PtNi nanowires,as well as selfsupporting three-dimensional PtCu nanowire and their catalytic performance.(1)Carbon-supported zero-dimensional Pt nanoparticles are the mainstream catalysts for commercial applications.In order to improve their catalytic activity,PtCu nanocrystalline was successfully prepared in situ on carbon supports by solvothermal method without capping agents and used in cathodic oxygen reduction and anodic methanol oxidation.The catalytic activity of PtCu nanocrystalline are superior to conventional carbon-supported platinum catalysts due to alloying synergistic effect.The results show that the PtCu Nanocrystalline exhibits excellent catalytic activity for oxygen reduction and methanol oxidation.The ORR mass activity is 11.5 times higher than the commercial Pt/C;the MOR mass activity is 15.3 times higher than commercial Pt/C.(2)Ultrafine(~2 nm)one-dimensional PtNi nanowires was prepared,witch by solvothermal method,which have lots characteristics,such as high conductivity,thermal stability,and structural flexibility characteristics.The catalytic results show that the one-dimensional PtNi nanowires exhibit excellent catalytic activity and stability for oxygen reduction.The mass activity is 7.2 times higher than commercial Pt/C,and the mass activity is not reduced after 10 K cycles potential cycling.(3)A three-dimensional self-supporting surface copper-rich PtCu nanowire networks was synthesized by solvothermal method,and then converted into a platinumrich surface(with a large amount of Cu defects)by chemical etching and electrochemical etching.Compared with the one-dimensional nanowire film,more prominent interconnect structure,and the small size of the constituent monomer endowed it high active area and catalytic activity.And the overall large size greatly weakens Ostwald ripening.The catalytic results show that the three-dimensional selfsupporting PtCu nanowire networks(with a large amount of Cu defects)exhibits excellent catalytic activity and stability: the ORR mass activity is 13.9 times higher than commercial Pt/C and not reduced after 100 K cycles potential cycling;the mass activity for MOR is 17.8 times higher than commercial Pt/C.