| Direct methanol fuel cells(DMFCs)are promising power sources for applications.Until now,it is widely recognized that platinum(Pt)catalyts are the common catalysts for methanol oxidation.The major barrier to further development of DMFCs is the high price and CO poisoning of Pt catalysts.Tungsten carbide(WC),as an inexpensive catalyst,has similar catalytic properties with Pt.The addition of WC to Pt has a favorable effect on methanol oxidation.However,the low conductivity and small surface area of WC limit its catalytic activity.Reduced graphene oxide(RGO)is selected as an ideal support for loading WC to improve the conductivity and enlarge the surface area of catalysts.In our work,reduced graphene oxide-supported tungsten carbide composite(WC/RGO)was prepared by program-controlled reduction-carburization technique.And it was characterized by X-ray diffraction(XRD),scanning electron microscope(SEM)and transmission electron microscope(TEM).It shows 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 Pt or ruthenium(Ru)via surface-limited redox replacement(SLRR)of sacrificial Cu adlayers.The prepared Pt modified or PtRu modified WC/RGO electrocatalysts were characterized by SEM,TEM and and cyclic voltammograms(CV).The results indicate that methanol oxidation requires the presence of the ensembles of neighboring Pt atoms,and a small amount of isolated Pt atoms possess low or even no activity for methanol oxidation.Meanwhile,the synergistic effect exists between WC,Pt and Ru play a key role in methanol oxidation,and WC has the potential to replace part of Ru for methanol oxidation.This research also provides another route to prepare a catalyst with controllable ultra low noble metals on WC/RGO for solving the problem of high cost of the catalyst. |
