Facile synthesis of nanoscale tantalum powder by electro-deoxidation of Ta2O5

We report a facile approach for the synthesis of nanoscale tantalum powder through the electro-deoxidation of Ta ₂O ₅ cathode in molten Na ₃AlF ₆-K ₃AlF ₆-AlF ₃. The cathodic process begins with a solid-liquid reaction between Ta ₂O ₅ and the electrolyte, resulting in the formation of M _xTaO _2+xF _1-x (M = Na, K) intermediates, which are then electrochemically reduced to tantalum directly. We developed a Ta ₂O ₅ cathode with a new porous structure, which contains interconnected microporous, mesoporous and macroporous structures, possessing properties such as high surface area, high pore volume ratios, and excellent accessibility to active sites. This novel cathodic pore structure material enabled the formation of uniform-sized M _xTaO _2+xF _1-x particles with a regular cubic morphology by providing abundant nucleation sites and promoting uniform growth of intermediate. The electrochemical decomposition of these particles and the nucleation, growth mechanisms of tantalum product were also investigated. Our study demonstrates the rational design and synthesis of hierarchically porous cathode materials can facilitate the controllable synthesis of nanoscale metal powders by the FFC process, and may open up new opportunities for the development of other materials with desired morphology and particle size.