Highly Dispersed Biocharcoal-based WC Composites: Fabrication And Its Electrocatalytic Properties

Direct methanol fuel cells?DAFCs?have some advantages such as high theoretical energy density and energy efficiency,thus making it a promising candidate in the area of new energy automobiles as well as portable electrical sources.However,platinum-based electro-catalysts are vulnerable to be poisoned by the intermediates-CH₃O,-CH₂O,-CHO and–CO.Tungsten carbide?WC?is a new non-noble metal catalyst material and has been considered as a promising catalyst,which could present a way to solve the problem of Pt being poisoned by removing the intermediates.As to the metal oxide,there exists a chemical interaction between the noble metal and the support.It was reported that TiO₂,WO₃has a high ability for methanol adsorption and accelerate the breaking breakage of O-H bond,which facilitates the decomposition of methanol for completing the oxidation on Pt active sites.In order to reduce the cost of platinum-based electro-catalysts and enhance the electrochemistry properties,we focus on the synthesis of new support and study of active components in the electrocatalysis.First,we developed the process of preparing biocharcoal due to the irregular porous structure and abundant source of bamboo raw materials,and then fabricated Pt-TiO₂-WC/BC by using bio charcoal as the support.The electrocatalytic properties of Pt-TiO₂-WC/BC were characterized.The results indicated that the oxidation of methanol can easily happened on the surface of Pt-TiO₂-WC/BC with a higher oxidation current of 658 mA/mg Pt^-11 than that on the surface of commercial Pt/C(448 mA/mg Pt^-1).The onset potential for CO oxidation on Pt-TiO₂?WC/BC and commercial Pt/C catalysts electrodes are 0.33 V and 0.42 V respectively.This 90 mv negative shift indicates the CO oxidation can occur at the lower potential on Pt-TiO₂?WC/BC.Also a negative shift of 90 mv for the peak current can be well defined from 0.47 V?Pt-TiO₂?WC/BC?to 0.56 V?Pt/C?,indicating that Pt-TiO₂?WC/BC electro-catalyst possesses the better capacity to remove the intermediate carbonaceous species from the active sites of Pt particles quickly,so it has a better tolerance to CO.Then biomass was used as the template and its unique multi-channel structure was fully duplicated on the WO₃ particles by simple impregnation and calcination.The prepared WO₃ particles which have multi-channel structure(_mc-WO₃)were evaluated as a support for methanol electro-oxidation.More importantly,CO could get oxidized at a lower potential?0.60 V?on the surface of Pt/_mc-WO₃ than that on commercial Pt/C?0.66 V?.