Preparation Of Pt/RGONRs With Polyol Reduction Methods And Catalytic Performance For Oxygen Reduction Reaction

With the development of science and technology,the demand for energy is increasing.As a member of proton exchange membrane fuel cells?PEMFCs?,direct methanol fuel cells?DMFCs?have attracted much attention due to its high energy conversion,reaction at room temperature and the availability of raw materials.The oxygen reduction reaction?ORR?occurring at the cathode is the rate-limiting reaction in DMFCs.In order to increase the utilization rate of Pt in the catalyst and enhance the catalytic performance,microwave-assisted polyol and acetate-assisted ambient temperature polyol method was used to synthesis a series of Pt/RGONRs supported catalysts and their electrocatalytic activity were investigated in ORR reaction.Reduced graphene oxide nanoribbons?RGONRs?supported platinum catalysts were prepared by microwave-assisted polyol method,in which Pt nanoparticles were uniformly dispersed with a mean particle size of 3.5 nm.During the synthesis,Pt ions were firstly attached to graphene oxide nanoribbons,then the encased metal ions and graphene oxide nanoribbons were reduced simultaneously by ethylene glycol.X-ray diffraction and X-ray photoelectron spectra indicate that the graphene oxide nanoribbons were partially reduced and the Pt nanoparticles were attached on the oxygen-containing groups on the surface of the support.Pt/RGONRs exhibited excellent activity for the oxygen reduction reaction?ORR?,and promising durability after 5000 cycles of accelerated durability tests.The enhancement of eletrocatalytic activity and better durability may be explicated by the well dispersed Pt NPs on the RGONRs and the attachment of Pt irons with the oxygen-containing groups before the reduction.Using aged chloroplatinic acid dispersion which was stewed under light for more than three months as the Pt precursor and RGONRs which were pre-treated by microwave as the carrier,Pt/RGONRs with better Pt nanoparticle dispearsion were prepared by Acetate-assisted ambient temperature polyol method.After investigating the effects of carrier with and without prereduction,the effect of different stewing time,different concentration of acetate and different kinds of acetate were also investigated.It was found that Pt/RGONRs-Zn which prepared by zinc acetate with a molar ratio of 20 times to Pt in the aged chloroplatinic acid,stewing for 12 h and pre-reduction RGONRs as carrier showed the best electrocatalytic activity for ORR.The mass specific activity of the catalyst at 0.85 V was 14.4 mA/mg_Pt,whch was 2 times better than the commercial Pt/C,indicating that the Acetate-assisted ambient temperature polyol method was a suitable method for preparation Pt based catalyst.Accorrding to the characteristic of reaction at room temperature,it is of great significance to study the mechanism of ethylene glycol reduction reaction.