Electrochemical Deposition of Flat Nanoporous Pt Layers with Small Pore Dimensions

Abstract

Nanoporous materials have received much attention because of their fundamental scientific significance and practical applications. In this study, we report electrochemically deposited nanoporous Pt layers from K2PtCl4 containing solutions that retain significantly smaller pore dimensions than previously reported nanoporous metal structures. The electrochemical surface area (ESA) of the electrodeposited Pt layers was significantly greater than the bulk Pt layers, despite their flat surface features. The roughness factor (R-f) of the Pt layers increased linearly with the deposition charge as their thickness increased. Electrodeposited Pt layers with 1500 nm height exhibited an R-f value of 450. The different R-f values of Pt layers estimated by different ESA evaluation methods indicated that the pores in the electrodeposited Pt layers responded differently towards the adsorption of H+, CO, and Cu2+. Transmission electron microscopy (TEM) analysis revealed the presence of channel-like pores inside the Pt layers. The mechanistic details of the electrochemical growth of nanoporous Pt layers are addressed based on the results observed from electrodeposition under different deposition potentials and precursor concentrations, as well as in different domains of the Pt electrodeposits. The physical properties of the pores present inside the Pt layers were investigated by heat and electrochemical treatments. The electrochemical behavior of the electrochemically deposited nanoporous Pt layers was uniquely different from that in previous reports; thus, the pores inside the Pt layers are not accessible to small redox species, such as glucose or Fe(CN)(6)(3-/4-). The unique characteristics of the nanoporous Pt layers demonstrated in this study will provide insights into the fabrication and application of nanoporous metal surfaces. (C) 2015 Elsevier Ltd. All rights reserved.