Contrasts between Mild and Harsh Oxidation of Carbon Nanotubes in terms of their Properties and Electrochemical Performance

Abstract

Fundamental studies and electrochemical applications of carbon nanotubes (CNTs) have impacted a wide range of disciplines. A key issue for CNT electrochemistry is to understand how the physical, chemical, and electronic properties of different CNT materials affect their electrochemical performance. We investigate the differences arising from CNTs undergoing mild (H2O2) or harsh (HNO3) oxidation processes. Morphological assessment and chemical characterization of CNT materials revealed that HNO3 treatment (CNT–HNO3) was effective in removing a large part of the metallic impurities, whereas H2O2 treatment (CNT–H2O2) was more proficient in eliminating carbonaceous imperfections in the starting CNT material (CNTprist). We investigated the electrocatalytic and electron‐transfer properties of CNTprist and oxidized CNTs on a variety of electrochemical probes, which are sensitive to carbon surfaces as well as its oxygen‐containing groups and/or metallic impurities. Electrochemical results show that, for the studied molecules, CNTprist and CNT–H2O2 exhibit mostly indistinguishable performances, whereas CNT–HNO3 yields an improved performance.

Corrigendum to “Unmodified and multi-walled carbon nanotube modified tetrahedral amorphous carbon (ta-C) films as in vivo sensor materials for sensitive and selective detection of dopamine” [Bios. Bioelectron. 118 (2018) 23–30]

“…In our opinion, this indicates a change in surface chemistry or structure rather than a change in diffusion regime. It has been shown that HNO3-treatment of CNTs results in the increase of oxygen functional groups and induces defects that affect particularly the oxidation of AA [218]. Similar chemical and structural changes have been observed by Pumera et al after electrochemical oxidation of CNTs [219].…”

Modification of C, O, and N Groups for Oxygen Reduction Reaction on an Electrochemically Stabilized Graphene Nanoribbon Surface

“…The C 1s HR-XPS spectra (Figures A and S4) showing a visible narrow peak and a small shoulder were deconvoluted in three peaks related to the following groups: sp 2 - (CC) and sp 3 -hybridized carbon (C–C) at 284.3 eV (Table S3); ,,,, alcohol and ether (C–OH, C–O–C) at around 285 eV (Table S3); ,,,, and carbonyl (CO, COOH) at around 288 eV (Table S3). ,,,, The two small peaks at 292.9 and 295.8 eV are attributed to K 2p, which is derived from the KOH solution employed during the electrochemical measurements and remained in the structure of GNR and GONR after electrochemical stabilization. For both GNR and GONR samples, there was an increase in the percentage content of C bonded to O (oxidation of C–C or CC bonds) and a displacement of the peak position of C (bonded to O) to lower energy (Table S3) after electrochemical stabilization.…”

“…Studies published in the literature have reported the involvement of N, − C, ,, and/or O ,,, groups (and their respective amounts) in ORR. A number of studies have also pointed out the acidic ,,,, or alkaline , medium used during the electrochemical measurements. ,,, Some works have also focused their study toward investigating the defects and edges ,,,,− ,− ,,,,, present on the nanostructured surfaces of metal-free carbon materials.…”

Oxidised carbon nanotubes as dual-domain synergetic stabilizers in electroconductive carbon nanotube flexible coatings

“…On the other hand, oxidation is known for ruthless deterioration of CNTs' unique structure making it a perfect model for our considerations. 19,20 Functionalisation degree, i.e. population of oxygen containing groups was determined both by means of thermogravimetric analysis and modied Boehm titration protocol (ESI †) and it was 4.2 mmol g À1 (both COOH and OH) ( Fig.…”