Finite Size Effects in Ordered Macroporous Electrodes Fabricated by Electrodeposition into Colloidal Crystal Templates

Abstract

Ordered macroporous electrodes (OMEs) formed by template synthesis have physical properties that are determined by the template. For colloidal crystal templates, these structures are inverse replicas of the fcc crystal structure with pore dimensions determined by the particle diameter in the colloidal crystal. The dimensions of the solid phase are determined by the interstitial space between the particles in the crystal.Here we demonstrate finite size effects in ordered macroporous gold electrodes. The adsorption of octadecane thiol is used to demonstrate that for structures fabricated from colloidal crystals with particle sizes less than 500 nm the resistance is dominated by surface scattering.

On “resistance overpotential” caused by a potential drop along the ultrathin high aspect ratio gold nanowire electrodes in cyclic voltammetry

“…The experimental results described here support the opinion that the finite size effect [22] complicates the employment of ultrathin NWs network over distance of several mm, and without high-resolution techniques to prepare contact lines and insulation of NW electrodes/electrochemical NW devices. Although ultrathin NW electrodes with lengths in the nm [44] can be used, the advantage of high aspect ratio network is not utilized in such applications.…”

“…Size-dependent intrinsic properties of nanomaterials are advantageous for some applications, e.g., chemiresistive sensing [4,[20][21][22][23][24][25][26][27]. However, these properties cause crucial deviations in the NWs behavior as electrodes from that of classical metal electrodes.…”

Electrodeposition of Nanometer-Sized Ferric Oxide Materials in Colloidal Templates for Conversion of Light to Chemical Energy

“…The largest solid features in the ferric oxide OME reported here come from the tetrahedral and octahedral sites in the colloidal crystal template [38]. The tetrahedral sites are formed from four spheres where the centers of the spheres form a tetrahedron.…”

“…For the OMEs fabricated here with 500 nm particles as templates, the diameters of the large solid regions, corresponding to the largest spheres that can fit into the tetrahedral and octahedral sites. These are 113 nm and 207 nm, respectively [38]. Thus the longest distances for carrier diffusion in these structures are 57 nm and 104 nm.…”

“…The assembly of the colloidal crystalline template followed literature preparations, described briefly as follows [37,38]. Sheets of FTO or wafers of gold evaporated on silicon were cut to 4.0 cm×2.5 cm dimensions and uses as substrates.…”