We report the modification of graphene oxide (GO) by thermal reduction to obtain reduced graphene oxide (RGO) and subsequent modification by sulfophenyl groups as well as the characterization of these materials by thermogravimetric analysis coupled with mass spectroscopy (TGA-MS). The chemical modification of RGO was carried out by the spontaneous reaction of RGO with in situ generated sulfophenyl diazonium ions. The three different types of materials were also characterized by elemental analysis, Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The characteristic absorption band at 1034 and 1160 cm⁻¹ in the FTIR spectrum of the sulfophenyl-modified RGO (SRGO), as well as Raman spectroscopy and TGA-MS data indicated that sulfophenyl groups were successfully grafted on RGO. The presence of organic molecules at the SRGO surface was also demonstrated by elemental analysis, transmission electron microscopy, energy dispersive X-ray spectroscopy and XPS. TGA data and elemental analysis results showed that the loading of sulfophenyl groups was about 12 wt% and UV-visible-near IR spectroscopy confirms the slight increase of the optical band gap of RGO after covalent grafting of sulfophenyl groups on its surface.

Grafting of polyarylene layers on the surface of Pb electrodes improves their selectivity for the CO₂ reduction to formate.

Nitrogen-doped graphene-based materials are of utmost importance in sensing and energy conversion devices due to their unique physicochemical properties. However, the presence of defects such as pyrrolic nitrogen and oxygenated functional groups reduces their electrical conductivity. Herein, a two-step approach based on the electrochemical exfoliation of graphite foils in aqueous mixed electrolytes followed by thermal reduction at 900 °C is used to prepare high-quality few layers of N-doped graphene-based materials. The exfoliations were conducted in 0.1 M (NH₄)₂SO₄ or H₂SO₄ and HNO₃ (5 mM or 0.1 M) electrolytes mixtures and the HNO₃ vol% varied. Chemical analysis demonstrated that the as-prepared graphene oxides contain nitro and amine groups. Thermal reduction is needed for substitutional N-doping. Nitrogen and oxygen surface concentrations vary between 0.23–0.96% and 3–8%, respectively. Exfoliation in (NH₄)₂SO₄ and/or 5 mM HNO₃ favors the formation of pyridinic-N (10–40% of the total N), whereas 1 M HNO₃ favors the formation of graphitic-N (≈60%). The electrical conductivity ranges between 166–2705 Scm⁻¹. Raman spectroscopy revealed a low density of defects (I_D/I_G ratio between 0.1 and 0.7) and that most samples are composed of mono-to-bilayer graphene-based materials (I_G/I_2D integrated intensities ratio). Structural and compositional stability of selected samples after storage in air for three months is demonstrated. These results confirm the high quality of the synthesized undoped and N-doped graphene-type materials.