Oxygen reduction on graphene sheets functionalised by anthraquinone diazonium compound during electrochemical exfoliation of graphite

Grafting redox-active molecules on graphene oxide through a diamine linker: length optimization for electron transfer

A redox-active molecule is grafted on graphene oxide (GO) via successive reactions. In the first step, GO is modified with diamine, which acts as a linker for the redox-active molecule. In the second step, the redox-active molecule is attached to the amino group of the linker by amide bond formation. Through these processes GO is partially reduced, enhancing its electrochemical properties. The structure of the functionalized GO is characterized by XPS, TGA, FTIR, and CV, and applied for electrodes in supercapacitors (SCs). The distance and direction of the redox-active molecule on the electrode affect the SC performance; ethylene diamine is the most promising linker to efficiently transfer electrons from the redox-active molecule to the electrode surface.

Tailoring the performance of electrochemical biosensors based on carbon nanomaterials via aryldiazonium electrografting

Carbon nanomaterials (CNs) offer some of the most valuable properties for electrochemical biosensing applications, such as good electrical conductivity, wide electrochemical stability, high specific surface area, and biocompatibility. Regardless the envisioned sensing application, endowing CNs with specific functions through controlled chemical functionalization is fundamental for promoting the specific binding of the analyte. As a versatile and straightforward method of surface functionalization, aryldiazonium chemistry have been successfully used to accommodate in a stable and reproducible way different functionalities, while the electrochemical route has become the favourite choice since the deposition conditions can be readily controlled and adapted to the substrate. In particular, the modification of CNs by electrochemical reduction of aryl diazonium salts is established as a powerful tool which allows tailoring the chemical and electronic properties of the sensing platform. By outlining the stimulating results disclosed in the last years, this article provides not only a comprehensively review, but also a rational assessment on contribution of aryldiazonium electrografting in developing CNs-based electrochemical biosensors. Furthermore, some of the emerging challenges to be surpassed to effectively implement this methodology for in vivo and point of care analysis are also highlighted.

N-self-doped porous carbon derived from animal-heart as an electrocatalyst for efficient reduction of oxygen

Biomass-derived nitrogen-self-doped carbon was prepared by a simple and green approach based on the direct pyrolysis of pork heart using KOH as an activation reagent at controlled temperatures (700-900 °C). The obtained samples displayed a specific surface area up to 1718.84 m² g^-1, high content of nitrogen (3.03%) and interconnected porous structure, which is able to expose abundant active sites and promote mass transfer. Electrochemical measurements showed that our catalyst possessed a high electrocatalytic activity for oxygen reduction reaction in alkaline solution that is equivalent to that of commercial Pt/C. The sample carbonized at 700 °C (PC-APHs-700) with the onset potential of 0.92 V and half-wave potential of 0.80 V possessed the highest concentrations of graphite and pyridine nitrogen and exhibited the best performance among the PC-APHs-T samples. In addition, PC-APHs-700 had a higher long-term stability and stronger methanol tolerance than commercial Pt/C. This work demonstrates that it is a promising approach to develop and utilize carbon materials with added value as effective metal-free cathode catalysts for alkaline fuel cells based on economic and environmental friendly renewable biomass.

Grafting of Diazonium Salts on Surfaces: Application to Biosensors

This review is divided into two parts; the first one summarizes the main features of surface modification by diazonium salts with a focus on most recent advances, while the second part deals with diazonium-based biosensors including small molecules of biological interest, proteins, and nucleic acids.

Polymer-derived Co/Ni–SiOC(N) ceramic electrocatalysts for oxygen reduction reaction in fuel cells

For the first time, the oxygen reduction reaction on transition metal and nitrogen doped SiOC-based electrocatalysts is studied.