The Noble Metal Nanoparticles Were Supported On New Carbon Materials And Study Of Its Use For Direct Full Cells

A3-4nm thickness of phosphotungstic acid (H3PW12O40, PW) layer was deposited on to the surface of multiwalled carbon nanotubes via sorption by ultrasonic method. These PW/MWCNT hybrids can be used as a promising supports for anode catalysts of the direct methanol fuel cell (DMFC). A facile polyol thermo-reduction method has been put forward to prepare PtIr (PtRu or Pt)/PW/MWCNT hybrids. To demonstrate the superiority of the as-prepared anode catalysts in the structure and the performance of methanol electro-oxidation, Pt and Pt bimetallic catalysits were prepared in similar synthetic strategy using MWCNTs as supports. A comparable investigation between these catalysts using different supports was carried out by transmission electron microscopy (TEM), cyclic voltammetry (CV), chronoamperometry and electrochemical impedance spectroscopy. In the presence of PW, PtIr (PtRu or Pt) nanoparticles can be uniformly dispersed on the surface of the MWCNTs in high-density with a smaller size and a narrower distribution, and these Pt and Pt bimetallic catalysts exhibited a significantly improved electrochemically active surface area (ECSA) and a remarkably enhanced activity toward methanol oxidation. Besides, these Pt and Pt bimetallic catalysts on PW/MWCNT hybrids also show longer operation stability and higher CO tolerance as well as better cell performance by compared with those on MWCNTs. The evaluation of anode catalysts in DMFC indicates that the observed power density depends on the intrinsic property of the size, dispersion and composition of Pt and Pt bimetallic catalysts. Carbon nanotubes (CNTs) supported Pdlr bimetal nanoparticles are synthesized with the Ir nanoparticles (NPs) as the linkers. The obtained Pdlr/CNTs hybrids were characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and inductively coupled plasma-atom emission spectroscopy. The results show the dispersion of PdIr NPs on CNTs can be improved by CNTs modification with Ir NPs, and the PdIr NPs were uniformly deposited on CNTs with the structure of Pd shell and Ir core (Ir@Pd). The average diameters of the Ir@Pd NPs on the CNTs increased from2.3to4.2nm with the Pd load on to the surface of Ir NPs. The electrochemical investigation exhibits the modification of Pd by Ir can promote the electrocatalytic activity of the Pd/CNTs catalysts for formic acid oxidation and the CNTs supported core shell PdIr catalyst possesses better electrocatalytic activity and stability for formic acid oxidation than the CNTs supported Pd catalysts.PdPt nanoparticles are homogeneously dispersed on the surface of graphene nanosheets.PdxPt nanoparticles with varied compositions (x=1,2,3and4) were synthesized by a thermolytic process at varied ratios of the H2PdCl4and H2PtCl6precursors.The composition of PdPt nanoparticles can be optimized at3:1Pd/Pt ratio,and as-prepared Pd3Pt1/g catalysts possess unique properties including a small size of PdPt nanoparticles, a high electroactive surface area and a large current density of formic acid oxidation.For comparison, some Pt catalysts, Pd catalysts are also prepared in a controlled experiment.The results showed that a Pd3Pti nanocomposite had excellent electrocatalytic activity and stabilities for the electro-oxidation of formic acid.