Electrochemistry of a Whole Group of Compounds Affected by Metallic Impurities within Carbon Nanotubes

Abstract

In this article, we demonstrate that iron oxide nanoparticles are responsible for the “electrocatalytic” effect of carbon nanotubes toward the reduction of organic peroxides. Taking into account earlier findings that hydrogen peroxide is susceptible to the same effect, we suggest that the electrochemistry of the entire class of compounds containing the peroxide group is affected by the presence of impurities within CNTs.

Metallic Impurities in Graphenes Prepared from Graphite Can Dramatically Influence Their Properties

“…[21] For comparison, CHP reduction was evaluated using Fe 3 O 4 nanoparticles (Fe 3 O 4 NPs) modified electrode which has a well-known catalytic effect on the reduction of hydrogen peroxide [11a] as well as organic peroxides. [18] It appears evident that a catalytic effect is occurring since a reduction signal starts at about À0.2 V with maximum at about À0.5 V, similar to the signals recorded with graphite-and TR-G-modified electrodes. Voltammetric signals resulting from blank solutions and in the presence of cumene hydroperoxide using Co-, Co 3 O 4 -, Cu 2 O-, Ni-, NiO-, MoO 2 -, and MoO 3 -nanoparticle modified electrodes (data not shown) showed no catalytic effect of these metals/metal oxides to the reduction of cumene hydroperoxide.…”

“…[17] To this point, we will present data that show how trace levels of residual metallic impurities present in the thermally reduced graphene material are capable of dominating its electrochemical properties. Cyclic voltammetry is employed to investigate the redox properties of three molecular probes: cumene hydroperoxide (CHP), [18] l-glutathione (GSH) [11c] and sodium hydrogen sulfide (NaHS). [19] These probes are well known to be very sensitive to presence of metallic impurities, such as Ni and Fe.…”

“…[11c, 18,19] Before discussing the influence of impurities on the electrochemistry of graphene, we need to introduce the standard material that graphene should be compared to. The electrochemistry of pure graphene as well as thermally reduced graphene resembles that of the edge-plane pyrolytic graphite electrodes (EPPG).…”

Recent advances in heterogeneous electrocatalysts for the hydrogen evolution reaction

“…This is the basis why we can use many carbon-based current collectors such as glassy carbon, carbon paper and carbon cloth in electrochemical experiments. [132][133][134] Heteroatom doped graphene nanosheets have recently been explored as metal-free HER electrocatalysts. heteroatom doping, is usually necessary in order to enhance its electrocatalyitc activity via forming heteroatom functionalities.…”

Enhancement of electrochemical and catalytic properties of MoS2 through ball-milling

“…From EDX and XPS analysis we detected the presence of metallic impurities after the ball-milling process. In particular, Fe-based impurities could have an active role in the catalytic hydrogen evolution reaction as they have in other electrochemical reactions such as the reduction of hydrogen peroxide, the reduction of organic peroxides, etc [20,21]. As such we tested different Fe-based materials (i.e.…”