Investigation of Platinum Dispersed on Reduced Graphene Oxide-supported Tungsten Carbide via Sacrificial Cu Adlayers for Methanol Oxidation

Reduced graphene oxide-supported tungsten carbide composite(WC/RGO)was prepared by program-con-trolled reduction-carburization technique.Scanning electron microscope(SEM)and transmission electron micro-scope(TEM)show that WC nanoparticles with a narrow distribution(10-20 nm)are highly dispersed both on the edge and between the layers of RGO.And then it was used as a support to load different low contents(no more than 0.4 wt%)of Pt via sacrificial Cu adlayers.The morphology and the electrocatalytic activity of the prepared catalysts were characterized by TEM and cyclic voltammograms(CV),respectively.The results indicate that a small amount of isolated Pt atoms show low or even no activity for methanol oxidation.With the increasing deposition cycles,the content of Pt and the ensembles of neighboring Pt atoms are increased,which makes the onset potential shift nega-tively and mass current density increase.The results demonstrate that controllable amount of Pt can be deposited on WC/RGO by galvanic displacement with Cu,and the extent and domain of Pt loading affect the electrochemical performance.Meanwhile,this research also provides another route to prepare a catalyst with ultra low noble metal on WC/RGO for solving the problem of high cost of the catalyst.

Synthesis and Characterization of Sphere-like Pt Nanoparticles Supported on DWCNT/WO_3 Nanorods with Electrocatalytic Activity

Tungsten oxide （WO3） nanorods, which were used to load platinum （Pt） nanoparticles, were investi- gated. H2WO4 nanorods with diameters from 10 to 50 nm were obtained when tungsten precursor was added into homogenous double-walled carbon nanotubes （DWCNT） and ethylene glycol （EG） solution. Nanosized rod-like WO3 were achieved after calcination of the DWCNT/H2W04 composite. Sphere-like Pt nanoparticles were loaded on the surface of the nanorods by EG in-situ reduction. Pt particles were isolated by DWCNT/WO3 nanorods and secondary accumulation could be prevented when Pt particles appeared in the DWCNT/WO3 nanorod/EG dispersion solution. Therefore, Pt nanoparticles with mean di- ameters of 2-6 nm could be obtained. Pt-deposited on DWCNT/WO3 nanorods exhibited high electrochemical activity, which could facilitate the low-cost mass production of Pt catalyst.

Nanostructure Architectures of Tungsten Carbide for Methanol Electrooxidation Catalyst

We reported a novel protocol to efficiently synthesize tungsten carbide （WC） nanomaterials with pure crystal structure and certain specific morphology. The key step in this protocol is the preparation of the catalyst precursor W18049 with surface oxygen vacancies. The existence of large quantities of oxygen vacancies gives plenty channels for diffusion and keeps the specific morphology of WC in the carbonization process. Efforts to build WC blocks with well-defined geometrical shapes （e.g., rods, wires, spheres and flakes） have further expanded its possibility to be the support for methanol electrooxidation catalyst. The platinum supported on pure phase WC materials served as an effective CO tolerant electrocatalyst for methanol oxidation. Electrochemical experiments indicated that the improved catalytic activity was related to the special morphologies of WC supports. Its sea urchin like feature leads to substantial interfaces between WC and Pt by preparing more anchor points for Pt loading and also the barriers for the subsequent crystal growth, which enhances the synergistic effect between WC and Pt.