We report a new method for the production of ordered 3D metal-nanowire network fi lms. The method utilizes a coating of lipid inverse cubic phase as the template for electrodeposition. We have produced platinum fi lms which show a previously unreported "single diamond" nanoarchitecture with Fd3m symmetry and a lattice parameter of approximately 132 Å. Their electrochemically accessible surface area is estimated to be > 40 m 2 g − 1 . The new methodology represents a facile route to 3D cubic nanostructures and thus provides a synthetically attractive route to the preparation of 3D nanostructured devices with diverse potential applications.Nanostructured metals and semiconductors have many important technological uses. They are commonly produced by templating soft materials such as diblock copolymers [ 1 ] or lyotropic liquid-crystal phases that form by amphiphile selfassembly. [ 2 ] These soft templates exhibit a range of different nanostructures that include hexagonal phases, based on simple 2D arrays of cylinders, and the more complex 3D bicontinuous cubic structures, based on mathematical surfaces known as the triply periodic minimal surfaces. Three different symmetries of bicontinuous cubic structure have been reported, based on the gyroid (G), double diamond (D), and primitive (P) minimal surfaces, which correspond to the space groups Ia3d (Q 230 ), Pn3m (Q 224 ), and Im3m (Q 229 ), respectively. In the inverse (Type II) cubic phases whose use as an electrochemical template is described here, the minimal surface lies at the centre of a continuous amphiphile bilayer which separates two continuous, but non-intersecting, water channel networks.Direct electrodeposition of nanostructured materials from normal topology (Type I) lyotropic liquid-crystal phases was fi rst reported by Attard and co-workers in 1997. [ 3 ] The method represents a reliable route to a range of nanostructured materials [ 4 ] under conditions that are suffi ciently mild to preserve the lyotropic mesophase structure during the electrodeposition process. Reported uses of direct electrochemical lyotropic templating using the normal (Type I) hexagonal phase are numerous, but in contrast there is only one reported case involving electrochemical templating from normal topology cubic phases. [ 5 ] There are two main reasons for this: fi rst, the cubic phase typically occupies only a small region of the composition-temperature phase diagram, and second, perhaps more importantly, the bicontinuous cubic phases are much more viscous than their hexagonal counterparts; [ 6 ] the combined result being that electrochemical templating from a cubic phase via the true liquid-crystal templating route is very difficult to achieve in practice.Nonetheless, the production of nanostructured materials with a bicontinuous cubic morphology is highly desirable, and even though the lyotropic liquid-crystal templating route has not been used extensively in this way, some alternative (albeit multi-step) approaches have been reported in the literature. The resulting bicon...

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Research highlight: Hydroxyapatite nanoparticles are synthesised using low-temperature co-precipitation methods with improved yield, smaller particle sizes and purity levels reaching requirements as bioceramics for bone and teeth replacement applications.

This paper presents the production of mesoporous metals with periodic 3D nanostructures, showing control over the lattice parameter and therefore pore and wire dimensions. The materials have “single diamond” (Fd3m) symmetry and are produced by deposition within a “cubic phase” template of the lipid phytantriol, in a process previously published. The current work shows a mechanism for tuning the nanoscale dimensions of the metal by the addition of a cosurfactant that progressively reduces the lipid bilayer curvature in the template. This swells its lattice parameter and therefore that of the deposited metal. Mesoporous platinum samples were characterized using X-ray scattering, electron microscopy, and electrochemical analysis. The structures exhibit unit cell sizes ranging from 13 to 20 nm, with wire thicknesses from 3.0 to 5.3 nm and estimated pore dimensions from 6.2 to 8.8 nm. The size control in these materials provides a mechanism for control of electrochemical behavior in electrocatalysis and sensors. Furthermore, the use of the templates in other metal and semiconductor materials suggests that size control offers possibilities for metamaterials with designed optoelectronic properties.

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We present an attractive method for the fabrication of long, straight, highly crystalline, ultrathin platinum nanowires. The fabrication is simply achieved using an inverse hexagonal (H) lyotropic liquid crystal phase of the commercial surfactant phytantriol as a template. A platinum precursor dissolved within the cylindrical aqueous channels of the liquid crystal phase is chemically reduced by galvanic displacement using stainless steel. We demonstrate the production of nanowires using the H phase in the phytantriol/water system which we obtain either by heating to 55 °C or at room temperature by the addition of a hydrophobic liquid, 9- cis-tricosene, to relieve packing frustration. The two sets of conditions produced high aspect nanowires with diameters of 2.5 and 1.7 nm, respectively, at least hundreds of nanometers in length, matching the size of the aqueous channels in which they grow. This versatile approach can be extended to produce highly uniform nanowires from a range of metals.