Nitrogen and Sulfur Co-Doped Graphene as Efficient Electrode Material for L-Cysteine Detection

Abstract

Two graphene samples co-doped with nitrogen and sulfur were synthesized by the hydrothermal method using thiourea as doping and reducing agent for graphene oxide (GO). An appropriate amount of thiourea was added to the aqueous dispersion of GO, previously sonicated for 30 min. The mixture was poured into an autoclave and placed in the oven for 3 h, at 120 and 200 °C. The samples were denoted NSGr-120 and NSGr-200, respectively, in agreement with the reaction temperatures. They were next morphologically and structurally characterized by advanced techniques, such as SEM/TEM, XPS, XRD, and FTIR. According to XPS analysis, the NSGr-120 sample has higher amounts of heteroatoms in comparison with NSGr-200, indicating that the reaction temperature is a crucial factor that affects the doping degree. In order to reveal the influence of the doping degree on the electrochemical performances of graphene-modified electrodes, they were tested in solutions containing L-cysteine molecules. The electrode with the best electrocatalytic performances, GC/NSGr-120, was tested to detect L-cysteine in a pharmaceutical drug, proving its applicability in real sample analysis.

Development of Lab-made Flexible Screen-printed Electrode based on S-Graphene Enriched with AuNPs and CuO for Electrochemical Detection of Tyrosine

“…41,42 Additionally, some slightly sharp, and wrinkled layers of S-G are noticeable. 43,44 The results show that the morphological characterization of each material in the conductive ink formulation has been successfully performed.…”

Features of the surface layer structure of the magnetosensitive materials functionalized by silica with thiourea groups and their applying for selective Cu(II) and Au(III) ions removal

“…In the XPS spectra (Fig. 8b) of the initial sample, C1s was deconvoluted into six different carbon states at 284.21 eV, 284.87 eV, 285.37 eV, 285.84 eV, 286.61 eV, and 287.82 eV, which were attributed to CSi [51], C-C + C-H, C-S, C--N, C--S, C-N [52], respectively. Thus, all samples contained the thione and thiol forms of the thiocarbamate group (Table 4).…”

Heteroatom Codoped Graphene: The Importance of Nitrogen

“…S and N codoped graphene based sensors have been extensively studied in the literature. − S and N codoped graphene was used by Li et al as a support for CuO nanoparticles to promote electrocatalytic glucose oxidation. A low detection limit of 0.07 μM was reported by Li et al and a detection limit of 0.5 μM was reported by Tian et al using S and N codoped graphene prepared with a one-step and cost-effective microwave assisted solvothermal method.…”

“…The codoped graphene based new sensor is much cheaper because it reduces the use of the expensive boronic acid. In the biological area, S and N codoped graphene based sensors have been constructed for l -cysteine, 320 hydroquinone/catechol, 321 cyanide, 322 an immunosensor for cardiac troponin I, 323 okadaic acid, 324 an immunosensor for cardiac troponin, 325 ascorbic acid, 326 , 327 and dopamine, 327 , 328 to mention just a few examples. In the same vein, pesticides 329 and toxic pollutants 330 can be detected.…”