Rhodium nanowires: Synthesis and nanostructure tailoring by controlling hydrogen evolution

•First demonstration of rhodium nanowire synthesis from a sulfate solution.•New chemistry allows for nanostructure tailoring by use of additives.•An insight into multiscale hydrogen bubble trapping and release.•A range of mechanical properties potentially enabled for use as resonators.

We report the use of rhodium sulfate solution for electrochemical synthesis of straight separable cylindrical rhodium nanowires that can be used as nanoresonators. We studied the effect of pH on the length uniformity and the effect of EDTA and polyethylenimine as additives on the development of the wire nanostructure. Multiscale frequency hydrogen bubble trapping and release was observed in the special case of a sulfate-based solution with 0.1 vol% polyethylenimine as an additive which results in formation of nanowires with ultrafine grain structure. The control over hydrogen co-reduction on the electrode surface and its bubble transport rate allowed for tailoring the nanostructure of the grown nanowires. Electrodeposition was performed at room temperature to avoid dissolution of the porous alumina template.