Template confined synthetic strategy for three-dimensional free-standing hierarchical porous nanocrystalline tantalum

• Three-dimensional free-standing hierarchical porous tantalum has been obtained.
• A template-confined magnesiothermic reduction process is demonstrated.
• Monolithic tantalum retained the disordered porous structures from xerogel templates.
• Tantalum products with high surface area contained of tantalum nanocrystals.

A template-confined strategy for preparing three-dimensional (3D) porous nanocrystalline tantalum was demonstrated. Free-standing hierarchical porous tantalum monoliths have been obtained for the first time from tantalum oxide xerogels as templates via low temperature magnesiothermic reduction. The similar morphology of tantalum products to that of tantalum oxide xerogels was retained after magnesiothermic reduction and hydrochloric acid etching. Monolithic porous tantalum is composed of cubic Ta nanocrystals, and possessed a high Brunauer-Emmett-Teller (BET) specific surface area (58 m2/g). The synthetic mechanism of porous nanocrystlline tantalum was also described. More importantly, combining the template confined route with displacement reaction, the strategy could be used to prepare 3D porous metals from porous metal oxides under relatively mild conditions.

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