Abstract: A template-free reverse micelle (RM) based method is used to synthesize pyrochlore nanostructures having photocatalytic activity. In one embodiment, the method includes separately mixing together a first acid stabilized aqueous solution including pyrochlore precursor A and a second acid stabilized aqueous solution including pyrochlore precursor B with an organic solution including a surfactant to form an oil-in-water emulsion. Next, equimolar solutions of the first and second acid stabilized oil-in-water emulsions are mixed together. Then, the mixture of the first and second acid stabilized oil-in-water emulsion is treated with a base to produce a precipitate including pyrochlore precursors A and B. After which, the precipitate is dried to remove volatiles. The precipitate is then calcined in the presence of oxygen to form a pyrochlore nanostructure, such as a bismuth titanate (Bi2Ti2O7) pyrochlore nanorod. The method of synthesizing the pyrochlore nanorod is template-free.

Abstract: The present invention relates to formation of nanocubes of sillenite type compounds, such as bismuth titanate, i.e., Bi12TiO20, nanocubes, via a hydrothermal synthesis process, with the resulting compound(s) having multifunctional properties such as being useful in solar energy conversion, environmental remediation, and/or energy storage, for example. In one embodiment, a hydrothermal method is disclosed that transforms nanoparticles of TiO2 to bismuth titanate, i.e., Bi12TiO20, nanocubes, optionally loaded with palladium nanoparticles. The method includes reacting titanium dioxide nanotubes with a bismuth salt in an acidic bath at a temperature sufficient and for a time sufficient to form bismuth titanate crystals, which are subsequently annealed to form bismuth titanate nanocubes. After annealing, the bismuth titanate nanocubes may be optionally loaded with nano-sized metal particles, e.g., nanosized palladium particles.