Functionalization of Contacted Carbon Nanotube Forests by Dip Coating for High‐Performance Biocathodes

Abstract

This work focuses on the use of electrically contacted carbon nanotube forests as an electrode material for the bioelectrocatalytic reduction of oxygen to water. The forests are directly grown by chemical vapor deposition on a conductive tantalum layer, which provides enough mechanic stability during several functionalization and enzyme immobilization steps. A pyrene bis-anthraquinone derivative (pyr-(AQ) 2) was attached via πstacking throughout the forest and was used as an anchor molecule for oriented immobilization of laccase. This led to high-performance biocathodes for oxygen reduction via direct electron transfer with absolute maximum current densities up to 0.84 mA cm À 2 at 0.2 V vs Ag/AgCl. The morphological changes during the wet chemical processes were studied by scanning electron microscopy (SEM) revealing cellular patterning of the forest structure. Despite these changes, the forest remained attached and electrically connected to the tantalum layer. The resulting bioelectrodes performed with satisfying stabilities under constant discharge conditions and kept 75 % of its initial performances after one week.

Low-dimensionality carbon-based biosensors: the new era of emerging technologies in bioanalytical chemistry

“…Additionally, mesoporous structures of electrodes applied with different in situ analytical techniques facilitate the in-depth study of interface elements and signal transduction and provide relevant information for the fabrication of more sensitive and stable biosensors. The combination of carbon nanomaterials has been a new trend to support, mainly, new configurations of biosensors operating under either direct or mediated bioelectrocatalysis [ 131 – 133 ].…”

Active coating of a water drop by an oil film using a MHz-frequency surface acoustic wave

“…It is an endemic process in the production of automotive, electronic, medical and aerospace components alongside many others, traversing the manufacturing of aeroplanes and satellites down to the manufacturing of humble pens and pencils [15]. Among the coating techniques found in industry one may count physical vapor deposition [16,17] in which the coating material is evaporated from a solid or liquid source and then delivered as a vapor onto a substrate, where it condenses; chemical vapor deposition [18,19], where the coating of the substrate is via a chemical surface reaction with a vapor phase; electrodeposition [20][21][22], where electrical potential is employed for the attraction of the coating materials in the form of ions or particulates to a charged substrate or via an electrochemical reaction at the surface of a charged substrate in contact with a precursor fluid; Sol-gel coating [23], which is a wet-chemical process for introducing a glassy or ceramic coating; spray coating [24][25][26][27], where a fast-moving flow of compressed air is steered into a stream of liquid coating and serves as a vector for transporting the coating to the target surface; and dip coating [28][29][30], where a coating liquid is put in direct contact with the target surface as in the happy blade approach or by dipping the target surface in a reservoir of a coating liquid. Dip coating as well as spray coating techniques are further employed to coat substrates by multiple immiscible liquid films [31][32][33].…”

Thermal Annealing‐Enhanced Bioelectrocatalysis in Membraneless Glucose/Oxygen Biofuel Cell based on Hydrophilic Carbon Fibers

“…[19,20] Among various electrode materials, carbon-based materials, such as carbon nanotubes (CNTs), carbon fibers (CFs), and graphene nanosheets, possessing good electrical conductivity, high specific surface area, chemical inertness, mechanical and thermal stability, have been widely used as electrode materials to immobilize enzymes in bioenergy devices. [21][22][23] However, pristine carbon materials exhibit poor surface activity and are hydrophobic, [24] which not only make the immobilization of enzymes difficult, but also prevent the access of reactants into the enzyme active sites. [16] Therefore, an active and hydrophilic electrode surface will be more favorable to construct an enzyme/electrode interface with enhanced catalytic kinetics.…”

“…Recent research interest has focused on exploiting novel electrode materials for the immobilization of enzymes to construct bioelectrodes in bioelectrocatalytic applications [19,20] . Among various electrode materials, carbon‐based materials, such as carbon nanotubes (CNTs), carbon fibers (CFs), and graphene nanosheets, possessing good electrical conductivity, high specific surface area, chemical inertness, mechanical and thermal stability, have been widely used as electrode materials to immobilize enzymes in bioenergy devices [21–23] . However, pristine carbon materials exhibit poor surface activity and are hydrophobic, [24] which not only make the immobilization of enzymes difficult, but also prevent the access of reactants into the enzyme active sites [16] .…”