This review paper specifically focuses on the fabrication and application of helical metallic structures with a size ranging from the micro- to nanoscale.

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This work reports on the electrodeposition of rhodium (Rh) nanowires with a controlled surface morphology synthesized using an anodic aluminum oxide (AAO) template. Vertically aligned Rh nanowires with a smooth and coarse morphology were successfully deposited by adjusting the electrode potential and the concentration of precursor ions and by involving a complexing reagent in the electrolyte solution. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses were used to follow the morphological evolution of Rh nanowires. As a heterogeneous electrocatalyst for hydrogen evolution reactions (HER), the coarse Rh nanowire array exhibited an enhanced catalytic performance respect to smooth ones due to the larger surface area to mass ratio and the higher density of catalytically active defects, as evidenced by voltammetric measurements and TEM. Results suggest that the morphology of metallic nanomaterials could be readily engineered by electrodeposition. The controlled electrodeposition offers great potential for the development of an effective synthesis tool for heterogeneous catalysts with a superior performance for wide applications.

In this work, we demonstrate how to synthesize a three-dimensional (3D) ordered PtAu nanoframe superstructure and evaluated its performance as an electrocatalyst. Compared to carbon supported platinum (Pt) nanocrystal electrocatalysts (wherein the aggregation- and carbon corrosion-induced fast degradation is a well-known drawback), the 3D PtAu nanoframe superstructure is free from aggregation and carbon corrosion. The 3D superstructure was self-assembled via drop-casting and evaporation using truncated octahedral PtAu nanoframes (TOh PtAu NFs) as building blocks that were produced by controlled wet-chemical etching of a TOh Au core whose edges and vertexes were selectively deposited with Pt atoms. Density functional theory calculations revealed that the surface alloy state of PtAu gave rise to an enhanced catalytic activity compared to pure Pt. Experimental investigations showed that such 3D superstructure electrocatalysts exhibited excellent mass transfer efficiency, higher catalytic activity and stability towards the methanol oxidation reaction (MOR) compared to a commercial Pt/C catalyst. The demonstrated 3D nanoframe superstructure shows great potential for practical catalytic application due to its high structural stability, high catalytic activity, high surface area and ease of fabrication.