| Direct methanol fuel cell clean, efficient, and is an ideal portable battery technology.PtRu alloy in the anode catalyst of direct methanol fuel cell catalysts is one of the bestperformance, but at present the bifunctional function and the electronic effect of type alloycatalyst on electrical catalytic repective roles in the process of methanol oxidation haven’trelated research to confirm， which developed difficult for the development of newmulti-component metal catalyst. In core-shell type catalyst, the nuclear layer metal effect theshell on electron, which can provide background basis for study the role of electronic effect,and laying a foundation of distinguish the role between the two kinds effect of alloy catalyst.Due to metal Ru nucleosynthesis is difficult. Ru@Pt preparation of core-shell type catalysthas not yet been reported at room temperature.This paper through two step chemical reduction synthesized different thickness of thinshell Ru@Pt core-shell nano catalyst, using X-ray diffraction spectrum (XRD), X-rayphotoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and X-rayenergy spectrum (EDS) means to represent the particle crystal structure, surface elements,microstructure and composition. The electrochemical catalytic performance of catalyticoxidation of methanol was test by using cyclic voltammetry, AC impedance andchronoamperometry to test.The characterization results show that: the prepared Ru@Pt core-shell type is sphericalnanometer catalystand the particle size is uniform, the average diameter is about7nm. In theXRD spectrum diagram of Ru@Pt nanoparticles catalyst, Pt (111) crystal plane diffractionpeak appears obvious excursion. The content of Pt is smaller, the migration is more obvious.Its main reason is that Ru nuclear layer has electronic induction effect on Pt shell layer, Pt metal lattice change. And in the XRD spectra of each sample almost not appear Ru diffractionpeak. So it is the further inference of the catalyst for the core-shell type catalyst. XPS showsthat the Pt0on Ru/Pt catalyst surface is higher than pure Pt, the main reason is that Ruelectronic effect on Pt. The content of Pt is smaller, the electronic effect of the catalyst isstronger.The test results of cyclic voltammograms in H2SO4electrolyte show that: the prepareddifferent Ru@Pt atom ratio catalyst no Ru, Pt metal clads Ru and protects it. So it furtherconfirmes that the prepared catalyst is core-shell structure. Different Ru/Pt atom ratio catalyst,between-0.64V to-0.4V, with the decreace of content of Pt hydrogen stripping peakincreases and then reduce act as "volcano", the Pt:Ru=0.5:1catalyst has the highest peak.The electrochemical test results of catalytic oxidation reaction of methanol show that:with the decreace of the content of Pt, the core-shell type catalyst activity of catalyticoxidation of methanol is not monotonous, but presents first increases and then decreases actsas "volcano", the Pt:Ru=0.5:1catalyst has the highest activity. In Ru@Pt core-shell typecatalyst, Ru electronic effect on Pt, which enhancements the catalytic activity of the catalysts.And with the increase of methanol concentration, the methanol catalytic oxidation peakcurrent of catalyst is higher. The the electronic effect is stronger, the the reaction series issmallerAc impedance test results show that: the concentration of methanol is greater, theresistance of different core-shell type Ru@Pt catalyst for methanol electric catalytic oxidationis smaller. And different catalyst in the same methanol concentration, with the Pt contentdecreases, in every methanol concentration the reaction resistance presents a trend of increasefirstly and then decrease. Electronic effect of catalyst can reduce the resistance in the processof the reaction... |
PDF Full Text Request