Platinum nanowires with pronounced texture, controlled crystallite size and excellent growth homogeneity fabricated by optimized pulsed electrodeposition

Abstract

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.