Shape-controlled Syntheses And The Catalytical Properties Of Pt And Pt-based Alloy Nanoparticles

In the past decade,platinum group metal nanomaterials have attracted much attention due to their excellent morphological diversity and catalytic performance.Pt and its alloy nanomaterials are indispensable and most effective catalysts for fuel cell,water electrolys,CO₂ reduction and hydrogenation.In addition to size effect,the composition,morphology and surface structure of Pt and its alloy nanomaterials are also key factors determining their catalytic performance.At present,many morphologies of Pt and its alloy nanomaterials have been successfully prepared by different synthetic methods,such as Pt octapod,PtNi nanoframe,PtCo nanoflowers,etc.In this paper,the syntheses of Pt and its alloy nanocatalysts were studied by oil-bath method and microwave method.Their electrocatalytic properties for the oxidation of methanol or formic acid as well as the catalytic hydrogenation of aromatic nitro compounds were preliminarily investigated.Uniform and monodispersive pompon-like Pt nanoparticles with an average size of 60nm were successfully synthesized with H2PtCl6?6H2O as the precursor,polyvinylpyrrolidone?PVP?as the stabilizer,C₆H₅COOH as the additive,tetraethylene glycol?TEG?as the solvent and reducing agent,and TEG as the solvent and reducing agent by oil bath at 160°C for 3hours.The products were characterized by TEM,XRD and XPS.The results showed that the catalytic activity of Pt nanopompons for the electrocatalytic oxidation of methanol or formic acid was about 2.0 or 1.9 times that of commercial Pt black,respectively.By means of microwave method,the Pt-Co alloy concave cubic nanoparticles were successfully prepared with H₂PtCl₆·6H₂O and CoCl₂·6H₂O as the metal precursors,PVP as a stabilizer,TEG as both a solvent anda a reducing agent,KI as an additive under microwave irradiation for 120 s.The Pt-Co alloy nanoparticles were characterized by TEM,XRD,SEM,XPS,UV-vis,HAADF-STEM and EDX.The results showed that the electrocatalytic activity of concave cubic Pt-Co alloy nanocatalyst for methanol or formic acid oxidation was about1.8 and 1.6 times that of commercial Pt black,respectively.For the hydrogenation of nitrobenzene?NB?to aniline?AN?by using Pt-Co alloy nanoparticles as a catalyst,the conversion of nitrobenzene and the selectivity of aniline were 99%and 87.9%,respectively,showing excellent catalytic activity and selectivity.By means of microwave method,the Pt-Co alloy concave cubic nanoparticles were successfully prepared with H₂PtCl₆·6H₂O and NiCl₂·6H₂O as the metal precursors,PVP as a stabilizer,TEG as both a solvent anda a reducing agent,KI as an additive under microwave irradiation for 140 s.The Pt-Ni alloy concave nanocubes were characterized by TEM,XRD,SEM,XPS,UV-vis,HAADF-STEM and EDX.The results showed that the electrocatalytic activity of concave cubic Pt-Ni alloy nanocatalyst for methanol or formic acid oxidation was about 2.5 and 1.8 times that of commercial Pt black,respectively.For the hydrogenation of p-chloronitrobenzene?p-CNB?to p-chloroaniline?p-CAN?by using Pt-Co alloy nanoparticles as a catalyst,the conversion of p-chloronitrobenzene and the selectivity of p-chloroaniline were 99%and 85.6%,respectively,showing good catalytic activity and selectivity.