Surfactant Controlled Growth of Niobium Oxide Nanorods

Abstract

This paper describes a solution-phase hydrothermal synthesis of crystalline niobium pentoxide (Nb2O5) nanorods. The methods reported herein yield uniform Nb2O5 nanorods with average diameters of 6 nm and lengths of 38 nm, which are directly synthesized from niobic acid by a hydrothermal process. The formation of Nb2O5 nanorods from niobic acid was studied in the presence of surfactants that stabilize the nanostructures. The crystalline Nb2O5 nanorods were relatively uniform in size and shape. The size of the Nb2O5 nanorods could be tuned through the choice of surfactant even in the absence of a worm-like micellar morphology. Amine, amide, ammonium, carboxylate, sulfonate and sulfate containing surfactants were systematically evaluated for their influence on the ability to form uniform Nb2O5 nanorods. The surfactants in this study had hydrophobic tails that were either straight or branched, such as a polymer, and contained either a single or multiple head groups. The nanorods grew by a process of oriented attachment of nanoparticles that was regulated by the surfactants added into the reaction mixture. The results of these studies indicate that this synthetic approach serves as a tunable platform to prepare single crystalline niobium oxide based nanostructures with well-defined morphologies and dimensions. This surfactant assisted formation of crystalline Nb2O5 nanorods could also have important implications in the design of other transition metal oxide based nanomaterials.

Nb2O5 nanotubes on carbon cloth for high performance sodium-ion capacitors

“…S2. Thus, pyridine in this process can effectively guide Nb 2 O 5 to form 1D construction, similar to other reports [25,26]. In addition, the acid solution in this system played important roles in the formation of Nb 2 O 5 nanostructures, which not only controlled the crystalline phases and structures of the electrode materials, but also acted as the etching agent to grow the hollow microstructures [27][28][29][30].…”

Design of Nickel Supported on Water-Tolerant Nb2O5 Catalysts for the Hydrotreating of Lignin Streams Obtained from Lignin-First Biorefining

“…By increasing the temperature and pressure in hydrothermal synthesis, the conversion of Nb 2 O 5 phases takes place following the sequence: amorphous Nb 2 O 5 → TT-Nb 2 O 5 → T-Nb 2 O 5 → H-Nb 2 O 5 (Nowak and Ziolek, 1999, Pinto et al., 2017, Valencia-Balvín et al., 2014). Nb 2 O 5 phase transitions are typically followed by a progressive decrease in the surface area, porosity, and acidity (Ali et al., 2017, Graça et al., 2013, Kreissl et al., 2017, Pinto et al., 2017, Raba et al., 2016, Valencia-Balvín et al., 2014). Among the crystalline phases, the TT-Nb 2 O 5 phase is the one presenting the highest number of oxygen vacancies in the structure, and so the greatest degree of polyhedral distortion (Pinto et al., 2017, Rani et al., 2014).…”

Surfactant-assisted synthesis of Mo–V mixed oxide catalysts for upgraded one-step conversion of glycerol to acrylic acid

“…28 In this work, the surfactant concentration used in the synthesis mixture was, approximately, 44 mM, a value higher than the CMC of CTAB and SDS in water, of 0.9-1.0 and 8.2 mM, respectively. 29,30 The formation of rod-like crystals in the presence of CTAB and SDS ionic surfactants was already reported in the synthesis of other materials. 31 The shape factor or critical packing parameter (g) values for these surfactants (Table 1), calculated from head group area, tail length and volume of hydrophobic portion (Scheme 2A and eqn (1)), are in the range expected for the structure aggregation to form cylindrical or rod-shaped micelles, 26 and the result ts well with that observed experimentally.…”