Facile Fabrication of Multifunctional Three-Dimensional Hierarchical Porous Gold Films via Surface Rebuilding

Abstract

We report here a novel one-step electrochemical method to fabricate three-dimensional (3D) micro−nano hierarchical porous gold films (PGFs) by the surface rebuilding of smooth gold substrates in a blank solution of NaOH with square wave potential pulse. The potential is controlled such that it involves repeated gold oxidation−reduction and intensive hydrogen evolution, where the hydrogen gas bubbles function as a dynamic template to shape the assembly of the gold nanoparticles from the oxidation−reduction. Particularly, this method is green, convenient, and economical, which enables us to fabricate the 3D porous structure from the metal itself requiring neither Au(III) species and additives in solution nor post-treatment of template removal. The pore formation and evolution have been characterized by scanning electron microscopy. The as-prepared 3D PGF is multifunctional, for example, (i) high electrocatalytic activity toward the oxidation of some fuel/biomolecules like ethanol, glucose, and ascorbic acid; (ii) strong surface-enhanced Raman scattering effect with the merits of being stable and easily renewed; and (iii) interesting transition from superhydrophilicity to superhydrophobicity by decorating with a self-assembled thiol monolayer.

Nanoporous Gold Electrodes and Their Applications in Analytical Chemistry

“…However, what is observed experimentally at a nanoporous gold electrode is a 10-fold increase in area that does not always lead to a 10-fold increase in the peak Faradaic current. For a redox molecule in solution that exchanges electrons quickly at an electrode surface (large standard rate constant, 0 ), the observed increase in Faradaic current was found to be only a few percent of what it should have been theoretically based on the "real" electrode area [24]. For redox couples with slow electron transfer kinetics, however, the opposite was observed [24].…”

“…This can potentially lead to larger currents, even for diffusing species, because Faradaic current typically scales linearly with electrode area; a significantly larger electrode area can potentially yield better S/N ratios, enhanced sensitivity, and lower detection limits. High surface area noble metal electrodes have been fabricated using a number of different approaches including hard templating of latex spheres or SiO 2 spheres [7,8,19,20], chemical dealloying [9,21], electrochemical dealloying [22,23], H 2 bubble formation [24], electrodeposition in the pores of nanopore membranes [1,2] as well as from ensembles of gold nanoparticles [5,6], gold microparticles [25,26], and electrospun gold nanofibers [3,4]. Each approach has its unique advantages and disadvantages.…”

Superwettability of Gas Bubbles and Its Application: From Bioinspiration to Advanced Materials

“…This work provides a new approach to designing interfaces for GERs [7,34] and GARs [35,36] in devices providing energy conversion and storage (such as fuel cells and metal-air batteries) and bubble-assisted electrodeposition processes. [37][38][39][40][41][42][43][44][45][46] Inspired by the lubricant layer of pitcher plants, the hydrophobic lubricant-infused slippery (LIS) interfaces are applicable to manipulation of bubbles in aqueous media. [47] The LIS track realized desirable bubble adhesion.…”

Influence of magnetic field on hydrogen reduction and co-reduction in the Cu/CuSO4 system

“…The system studied is a copper substrate in contact with an acid sulphate electrolyte containing 1.2 M H 2 SO 4 , either copper-free or containing 0.3 M CuSO 4 . A 100 mL, round-bottom cylindrical cell was used.…”