Nitrogen and Sulfur Co-Doped Graphene as Efficient Electrode Material for L-Cysteine Detection
Codruța Varodi,
Florina Pogăcean,
Alexandra Cioriță,
Ovidiu Pană,
Cristian Leoștean,
Bogdan Cozar,
Teodora Radu,
Maria Coroș,
Raluca Ioana Ștefan-van Staden,
Stela-Maria Pruneanu
Affiliations
Codruța Varodi
National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat Street, 400293 Cluj-Napoca, Romania
Florina Pogăcean
National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat Street, 400293 Cluj-Napoca, Romania
Alexandra Cioriță
National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat Street, 400293 Cluj-Napoca, Romania
Ovidiu Pană
National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat Street, 400293 Cluj-Napoca, Romania
Cristian Leoștean
National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat Street, 400293 Cluj-Napoca, Romania
Bogdan Cozar
National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat Street, 400293 Cluj-Napoca, Romania
Teodora Radu
National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat Street, 400293 Cluj-Napoca, Romania
Maria Coroș
National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat Street, 400293 Cluj-Napoca, Romania
Raluca Ioana Ștefan-van Staden
Laboratory of Electrochemistry and PATLAB, National Institute of Research for Electrochemistry and Condensed Matter, 202 Splaiul Independentei Street, 060021 Bucharest, Romania
Stela-Maria Pruneanu
National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat Street, 400293 Cluj-Napoca, Romania
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.
