Electrochemical Detection Using Nanoporous Structures

Nanoporous electrodes are a unique class of nanostructured electrodes for promising electrochemical sensor applications because of a range of important attributes which include but are not limited to: high surface area, interesting catalytic properties, fast mass transport and low Ohmic resistance drops, potentially low cost and good fouling tolerance [1, 2]. In addition to the conventional concept of enlarged surface area, nanoporous structures provide a unique environment for reactive molecules. Once a reactant molecule enters a nanopore, the probability of interaction between the nanoporous electrode surface and the molecule is increased compared with that on a flat electrode. The molecule involved in a sluggish electrochemical reaction can enter deep into the nanopore, leading to longer penetration depth. Consequently, the heterogeneous charge transfer gets facilitated and the amperometric response of sluggish faradaic reactions can be selectively enhanced. This will selective amperometric detection, in which the selectivity and sensitivity could be tuned by the depth, shape, and interconnectivity of the nanopores. In addition, the nanoporous structures resulted nano-confinement effects can prevent reactive intermediates from escaping back to the bulk solution. Expedited by the rapid advance of nanomaterial engineering and manipulating technology, nanoporous electrodes will be a strong impetus to a wide range of emerging areas such as in-situ and remote monitoring and controls [3, 4].

In this presentation, we will introduce the structural effects of nanoporous materials including discriminative electrokinetics, the nano-confinement effect and electrical double layer overlapping, the fabrication nanoporous microelectrodes, the characterization of their porous structures, and their nanopore-induced enhanced electrochemical responses to several interesting molecules such as nitrate, nitrite, and chlorides.