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Electroless plating of magnetic materials on catalytically active noble metal seeds is a powerful tool to design highly efficient recyclable catalysts. For the electroless plating procedure of metallic nanotubes in porous polymer templates, a sensitisation and activation process of the template is necessary. Therefore, metallic seeds are created on the surface of the polymer, which then enable the selective heterogeneous nucleation of a metal film on the template's surface. By choosing the metals for seeds and structures wisely, different functional materials can be purposefully combined. In this work magnetically recoverable catalysts were designed, which consist of magnetic NiCo nanotubes as carrier for catalytically active Pd seeds. The synthesised catalyst structures were thoroughly characterised by SEM, TEM, EDX, XRD, XPS, ICP-OES, VSM and then tested in the 4-nitrophenol reduction reaction, which was monitored by UV-Vis spectroscopy. After the reaction the structures were recycled and reused without a decrease in activity.

The method of electroless plating offers a facile synthesis route to high-aspect ratio metal nanotubes. Despite the simplicity of the method, the traditional approach involves hazardous and toxic chemicals; to change this Green Chemistry has come into play. Since both, nanotechnology and Green Chemistry, have become important research topics, the combination of these offers new opportunities. According to the concept of Green Chemistry, Pd nanotubes were produced by using nonhazardous chemicals. The challenge was to rebuild the sensitisation and activation process of electroless plating and to find green reaction parameters for controlling the auto-catalysed heterogeneous nucleation of Pd. The produced Pd nanotubes were characterised by SEM and EDX. Furthermore TEM characterisation was done for determining the structural properties of Pd NTs. The efficiency of the reaction was quantified by ICP-OES and XPS measurements. To illustrate that green synthesized nanomaterials can be compared with conventionally prepared catalysts, the Pd nanotubes were tested in a model reaction to determine their catalytic activity. For this purpose the reduction of 4-nitrophenol to 4-aminophenol with NaBH4 was chosen, which also finds application in the synthesis of acetaminophen.

Platinum nanowires with controlled texture and crystallite size were fabricated in nanoporous ion-track etched polycarbonate membranes by electrochemical deposition with different potential pulse sequences. The application of specific potential pulses ranging from −0.5 V to −1.3 V and reverse pulses with +0.2 V allows switching between a light 〈111〉 texture and a pronounced 〈100〉 texture along the nanowire axis. At the same time, the crystallite size determined by XRD was significantly increased from approx. 20 nm to 45 nm, yielding oligocrystalline wires, which are very difficult to obtain with Pt electrodeposition due to its pronounced tendency towards instantaneous nucleation. TEM verified the increase of the calculated average crystallite size of the Pt nanowires. We have been able to prove the necessity of each potential pulse and pulse duration by changing them in a systematical way. Key strategy to achieve large crystallite sizes and a pronounced texture was to reduce oversaturation of Pt adatoms during the reduction step and to preferentially dissolve lattice defects and nucleation sites by anodic removal. Additionally, the homogeneity of the Pt nanowire growth was evaluated for the applied pulse sequences by SEM. The results show that by reducing the deposition current density, the uniformity of the Pt nanowires was strongly enhanced. The proposed rational synthetic strategy allows to optimize the crystallinity, texture and monodispersity of Pt nanowires and is thus of considerable relevance for tailoring the functional properties of these structures.

A dependable and mild deposition procedure for the first electroless synthesis of platinum nanotubes in ion track etched polycarbonate was developed. It utilizes ethylenediamine to adjust the reactivity of Pt(IV) towards reduction and allows the controlled deposition of nanoscale platinum films, wires and tubes at room temperature. Single crystal structure determination proves the formation of Pt(II) as a side product next to elemental platinum. Highly polycrystalline nanostructures of 100 to 900 nm diameter and up to 30 μm length were obtained and characterized by TEM, SEM, EDS and XRD. The platinum nanotubes showed high activity in the electrooxidation of methanol in acidic environment. To illustrate the possibilities for synthesizing bimetallic nanotubes in the presented system, ruthenium was introduced by electroless and spontaneous deposition methods. The corresponding surface-normalized current densities are strongly dependent on the preparation method and can surpass commercial fuel cell catalysts, confirming the efficiency and flexibility of electroless metal plating in the preparation of nanomaterials.

Asymmetric calix(4)arenes (5) consisting of three different phenolic units were obtained by fragment condensation either of a trinuclear compound (1) with a 2,6-bis(bromomethyl)phenol (2) or a dinuclear compound (3) with a bisbromomethylated dimer (4) in a dioxane–TiCl4 system.