Platinum-Based Nanowire Networks with Enhanced Oxygen-Reduction Activity

Abstract

Pt-alloy compound causes the formation of a highly porous nanowire network with a mean branch thickness below 25 nm and a pore intercept length below 35 nm. The oxygen reduction capability of the resulting electrodes was analysed in a micro-solid oxide fuel cell setup at elevated temperatures (598 − 873K). Here, we demonstrate that these nanoporous thin films excel "state-of-the-art" fuel cell electrodes in terms of catalytic activity and thermal stability. The nanoporous Pt electrodes exhibit exchange current densities that are up to 13 times higher than conventional Pt electrodes, measured at 648 K. It is shown that the enhanced catalytic activity of these Pt electrodes is achieved through the engineering of the materials d-bands due to the addition of yttrium as ternary constituent.

Light Manipulation in Metallic Nanowire Networks with Functional Connectivity

“…The main question is to find a process where the connectivity among disordered units can be tailored and controlled. We here use metallic nanowire networks fabricated by dealloying, a wet-chemistry technique [29,30,31,32,33,34,35,36,37]. These systems appear similar to porous materials, but with the unique difference that the short-range order, i.e.…”

“…The selective dissolution causes a re-organization of the remaining metal matrix, which is accompanied by the formation of a nano-sized open network of pores [29,35,36,37,39]. The size of each pore is in the range of 5−30 nm, and is scalable via annealing or compositional changes [31,30,40,32,33,34]. Due to these features, dealloying is an ideal process to fabricate random nanowire networks from metallic thin films.…”

“…The nanowire networks used in this work are fabricated by simple wet-chemistry and are not constrained with respect to their active area. In addition, our Pt-Y-Al films can sustain very high temperatures [30], making them a quite promising candidate for high temperature applications in energy harvesting, such as thermovoltaics. These applications are naturally enabled by the presence of an absorbing state [52].…”

Scalable, ultra-resistant structural colors based on network metamaterials

“…While immersing the film in a 4 molar aqueous solution of NaOH for 60s, the less noble Al in the Pt-alloy thin film is subsequently removed and the remaining metal reorganises to a network with an open porosity, mimicking neural architectures. Characteristic geometrical features of the network can be altered by changing the etching time, the etchant concentration or the initial composition of the thin film [32][33][34][35][36].…”

Chemical Engineering of CuSn Disordered Network Metamaterials

“…From different studies on the dealloying of ternary alloys, it is known that the addition of a third element can influence network topology: e.g. the addition of yttrium to Pt-Al networks led to a significant coarsening of the network topology, 5 while a significant refinement of the pore and ligament size was observed when adding even small quantities of Pt to Au-Ag to the precursor, e. g. prior to dealloying 6,7 as well as by adding Ni to Cu-Mg. 8 We argue that as Cu is the dominant diffusion species of the two elements, Cu & Sn, Sn can pin the step-edges of growing struts of the network, resulting in a reduction of the scale of the porosity and consequently the edge length. 6,9 Secondly composition changes might also result in a shift of plasmonic resonances, as it is found in Ag-Au nanoparticles with different compositions.…”