NANOSTRUCTURED COMPOSITE MATERIALS, DIRECT SYNTHESIS PROCESS FOR COMPOSITE MATERIALS CONTAINING TUNGSTEN AND TIN SEMI-CARBIDE DEPOSITED ON CARBON OR TUNGSTEN SEMI-CARBIDE DEPOSITED ON CARBON AND USE THEREOF

摘要

The invention relates to nanostructured composite materials which contain tungsten and tin semi-carbide deposited on carbon or tungsten semi-carbide deposited on carbon and to a process for preparing the same, the composite materials being intended to be used either as catalysts or in electrochemical applications. The claimed material contains nanoparticles of WC, metallic Sn, and C or nanoparticles of WC and C, obtained by the carbothermal reduction of a reaction mass with a precursor atomic ratio W:Sn:C, where a/b = 0.01...7, c/a = 3.5...200 and c/b = 3...200, such that c/(a+b) = 4...50, the average size of WC and metallic Sn particles having values ranging between 5...100 nm, preferable beetween 10...70 nm. The claimed process has two steps: a. obtaining the reaction mass by physical mixing of the precursors by pestle crushing, grinding or ultrasonic treatment or by operations of solution mixing, evaporation, impregnation, melt extrusion or lyophilisation of precursor solutions, where the W precursor can be a salt, an oxide or a W complex, preferably selected from WO, chlorides, fluorides, bromides and the like, which by heating to temperatures of up to 600°C produce W oxides, b. carbothermal reduction of the reaction mass in a reactor, by heating the same in an inert atmosphere or in vacuum, to a temperature ranging between 500...1500°C, preferably between 800...1200°C, for maximum 48 h, the working pressure being smaller than 1000 Pa and the reaction time, depending on the characteristics of the reactor, ranging between 1 min...48 h, preferably between 5 min...8 h, and the material containing only WC and C is obtained by removing Sn from the first material by dissolving metallic Sn, using a strong acid without oxidant character, followed by the separation of Sn from the suspension by filtering, centrifuging or decanting the same.