Electrochemistry at nanoporous interfaces: new opportunity for electrocatalysis

Abstract

Physical and electrochemical features of nanoporous electrodes arising from their morphology are presented in this perspective. Although nanoporous electrodes have been used to enhance electrocatalysis for several decades, the origin of their capability was understood on the basis of enlarged surface area or crystalline facet. However, considerable attention should be paid to the fact that nano-confined space of nanoporous electrodes can significantly affect electrochemical efficiency. Molecular dynamics in nano-confined spaces is capable of offering much more chances of interaction between a redox molecule and an electrode surface. The mass transport in the nanoporous electrode depends on various pore characteristics such as size, shape, charge, connectivity, and symmetry as well as molecular properties such as size, charge, and kinetics. Moreover, when the pore size is comparable to the thickness of an electric double layer (EDL), the EDLs overlap in the porous structure so that electrochemically effective surface area is not the same as that of the real electrode surface. These unique properties come from simply nanoporous structure and suggest new opportunity to innovative electrocatalysts in the future.

RETRACTED ARTICLE: An overview of CO2 electroreduction into hydrocarbons and liquid fuels on nanostructured copper catalysts

“…The generation of the saturated hydrocarbons and C 3 -products may be caused by the hierarchical porous structure of the copper foam because the residence time of the various intermediates within these confined spaces of pores may increase, allowing for the generation of products that were not observed on smooth copper electrodes. The idea that nanoporous electrodes favor the reaction pathways that are different from those observed at smooth electrodes via a confinement mechanism has been studied in detail in the electroreduction of O 2 at nanoporous Pt electrodes (27,58). Nanostructured cuprous oxide (Cu 2 O) has been reported as one of the promising nanostructured electrode materials for the efficient and selective production of ethylene from CO 2 electroreduction.…”

“…Thus these reactions are of great interest as one possible tool to deal with global warming. Nanostructured metals, a representative class of nanostructured materials, have attracted huge attention over the last decade due to their intriguing properties and promising potential for various typical applications, such as catalysis and energy conversion/storage systems (21)(22)(23)(24)(25)(26)(27)(28)(29). Due to their unique properties, such as enlarged specific surface area and 2-and 3-dimensional interpenetrating structures, nanostructured metals can provide easy diffusion pathways to the substrate to access the electrolyte ions and a large number of active sites for the catalysis, leading to a faster reaction with high efficiency (30)(31)(32).…”

Electrodeposition of three-dimensionally assembled platinum spheres on a gold-coated silicon wafer, and its application to nonenzymatic sensing of glucose

“…The concentration of ascorbic acid (0.1 mM) was chosen based on the normal physiological level of ascorbic acid, which is much lower than that of glucose (3~8 mM) [21]. Elimination of interference by ascorbic acid during the electrochemical detection of glucose indicates that the porous nature of 3-D assembled Pt sphere structures is effective for distinguishing between the different electrode kinetics of ascorbic acid and glucose as observed on porous metal surfaces [18,11].…”

“…One notable aspect highlighted in previous investigations on the electrodeposition of Pt nanostructures is that these Pt particles are twodimensionally (2-D) arrayed on the electrode surfaces [7][8][9][10]. Although 2-D nanostructured Pt surfaces exhibited electrocatalytic and surface-enhanced Raman activities, three-dimensionally (3-D) assembled micro/nanostructures offer more versatile applications based on their porous nature, particularly in electrochemistry [11,12]. However, electrochemical deposition of 3-D assembled Pt micro/nanostructures requires complicated procedures including template assembly and removal steps [13][14][15].…”

Electrochemical atomic force microscopy: In situ monitoring of electrochemical processes

“…These electrochemical (EC) reactions strongly depend on: (i) the reactants mass transport from the bulk solution to the charged surface and (ii) the rate of the electron transfer between the electrolytes and the metallic surface [4]. If the former is the slower phenomenon involved in the reaction the system is diffusion limited, otherwise the system is called charged limited [4,5]. Since these two phenomena are strictly interdependent, knowing the relationships existing between the surface reactivity and the morphology of the solid-liquid interface is of crucial importance in order to obtain an efficient control of the electrochemical process.…”