Preparation Of Modified Reduced Graphene Oxide Supported Tungsten Base Composite And Its Electrochemical Properties

Direct methanol fuel cells(DMFCs)are promising power sources for applications.Until now,it is widely recognized that platinum(Pt)base catalyts are the most common catalysts for methanol oxidation(MOR).The major obstacles to further development of DMFCs are the high price and vulnerability to CO poisoning of Pt catalysts.Tungsten carbide(WC),as a non-noble catalyst,has similar catalytic properties with Pt.The addition of WC to Pt has a favorable effect on resistance to CO poisoning through the synergistic effect between Pt and WC.However,the low conductivity and small surface area of WC surpress the real application in DMFCs.Reduced graphene oxide(RGO)is selected as an ideal support for loading WC to improve the conductivity and surface area of catalysts.RGO intercalation compound has specific physicochemical characteristics such as excellent chemical stability,high electrical conductivity,good mass and charge transfer ability and so on.However,RGO is hard to form intercalation compound because of the smooth and inertness of its surface and the large size of WC.In this work,three different methods were introduced to prepare WC-RGO intercalation compound.Firstly,graphene oxide(GO)was obtained,and then GO was used as the support to fabricate WC-RGO intercalation compound through the methods of N-doping modification and thiourea anchoring.In the meantime,(tungsten base)-graphene intercalation compound was derived by electric reduction and then was used to synthesize WC-RGO intercalation compound.On the support of WC-RGO intercalation compound from different methods,a small amount of Pt was loaded to form Pt/WC-RGO intercalation compound by a microwave-assisted and electrochemical atomic layer deposition method(EC-ALD)respectively.The samples were characterized by XRD,SEM,TEM and Raman.As to Pt/WC-RGO(M)intercalation compound,N-doping modification of RGO not only improved the electroconductivity of RGO,but also increased the active sites to load more Pt and WC which would promote the synergistic effect for MOR.In the process of synthesizing Pt/WC-RGO(T)intercalation compound,thiourea was used as the anchoring,inducing reagent and sulfur source.Ultra small-sized WC sandwiched in RGO layers forming WC-RGO intercalation compound was successfully prepared.The special intercalated structure provided not only the intimate contact between Pt and WC to make full use of synergistic effect but also few-layer RGO to increase mass and charge transfer ability for MOR.In the case of Pt/WC-RGO(E)intercalation compound,the graphite foil was firstly electrolyzed to obtain the precursor of(tungsten base)-graphene intercalation compound in the electrolyte with ammonium metatungstate(AMT),and then the support was modified with Pt by EC-ALD.Pt/WC-RGO(E)intercalation compound was obtained with higher content of WC.