Solid Oxide Membrane (SOM) Process for Facile Electrosynthesis of Metal Carbides and Composites

Metal carbides (MCs) and composites including TiC, SiC, TaC, ZrC, NbC, Ti₅Si₃/TiC, and Nb/Nb₅Si₃ have been directly electrosynthesized from their stoichiometric metal oxides/carbon (MOs/C) mixture precursors by an innovative solid oxide membrane (SOM)-assisted electrochemical process. MOs/C mixture powders including TiO₂/C, SiO₂/C, Ta₂O₅/C, ZrO₂/C, Nb₂O₅/C, TiO₂/SiO₂/C, Nb₂O₅/SiO₂ were pressed to form porous pellets and then served as cathode precursors. A SOM-based anode, made from yttria-stabilized zirconia (YSZ)-based membrane, was used to control the electroreduction process. The SOM electrochemical process was performed at 1273 K (1000 °C) and 3.5 to 4.0 V in molten CaCl₂. The oxygen component contained in the MOs/C precursors was gradually removed during electroreduction process, and thus, MOs/C can be directly converted into MCs and composites at the cathode. The reaction mechanism of the electroreduction process and the characteristics of the obtained MCs and composites products were systematically investigated. The results show that the electrosynthesis process typically involves compounding, electroreduction, dissolution-electrodeposition, and in situ carbonization processes. The products can be predesigned and controlled to form micro/nanostructured MCs and composites. Multicomponent multilayer composites (MMCs) have also been tried to electrosynthesize in this work. It is suggested that the SOM-assisted electroreduction process has great potential to be used for the facile and green synthesis of various MCs and composites.