In this work, employing the Hibiscus rosa sinensis (HRS) flower extract as a green reducer for graphene oxide (GO) reduction and functionalization of rGO using piperazine is proposed. A chemically modified screen-printed carbon electrode (SPCE) was prepared using piperazine functionalized reduced graphene oxide (P-rGO). Electroanalytical techniques such as amperometry and differential pulse voltammetry (DPV) were used to investigate the sensing capability of P-rGO modified SPCE towards the detection of Hg 2 + ions. The oxidation peak observed in the cyclic voltammetry was due to the interaction between piperazine (amine) and mercury ions. Piperazine plays a major role in improving the sensitivity of the developed sensor towards mercury cation detection, while the P-rGO is used as a platform for the incorporation of Hg 2 + .The developed sensor exhibits a high sensitivity of 0.00327 μA/pM over a wide linear range of 0.2 pM to 2 pM, with a detection limit of 0.0557 pM.
Herein, Tecoma stans (TS) flower extract was used as an efficient green reducing agent for graphene oxide (GO) to produce reduced graphene oxide (rGO) for the first time. The organic heterocyclic benzotriazole (BTA) was incorporated onto the rGO surface through a nucleophilic substitution reaction to produce covalently bonded BTA-rGO. The prepared materials were analyzed by UV-visible spectroscopy, powder Xray diffraction measurements (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and Scanning Electron Microscopy (SEM). A screen-printed carbon electrode (SPCE) was modified with BTA-rGO. The fabricated electrode was electrochemically analyzed by using K 3 [Fe (CN) 6 ] as a redox probe. To evaluate the sensing ability of BTA-rGO/SPCE electrode towards arsenic ions using differential pulse voltammetry (DPV) and amperometry techniques. The BTA functional was play the major role in significant improving the conductivity and sensitivity of the designed electrode. The BTA-rGO/SPCE modified electrode demonstrates voltammetric determination of As 3 + ions with a limit of detection, high sensitivity, and linear range values of 2.89 nM, 1.8 μA nM À 1 , and 2-40 nM, respectively. Furthermore, all of these impressive results indicate that BTA-rGO can be used as an electrodematerial with capability for electrochemical arsenic sensors. The fabricated sensors showed repeatability and reproducibility in this study.
4-Nitrophenol (4-NP) is a hazardous organic pollutant with detrimental effects on plants, animals, and humans. Detection of 4-NP in the environment is therefore a necessary requirement. We demonstrate a facile green synthesis of nickel-oxide (NiO) nanoparticles employing Brassica oleracea vegetable extract (cauliflower) as a green stabilizing and reducing agent. Green synthesized NiO nanoparticles were used as an efficient electrode material for the highly sensitive electrochemical detection of 4-NP. The abundant polyphenolic component in the vegetable extract of Brassica oleracea is capable of reducing and stabilizing C 2 NiO 4 into NiO nanoparticles. The as-synthesized NiO nanoparticles were characterized by UV-Vis spectroscopy, FTIR spectroscopy, Raman spectroscopy, photolumines-cence spectroscopy, and X-ray photoelectron spectroscopy (XPS), and the structural phase of NiO nanoparticles was confirmed using powder X-ray diffraction technique. The surface morphology of the NiO nanoparticles was analyzed using scanning electron microscopy (SEM). Linear sweep voltammetry (LSV) and Differential pulse voltammetry (DPV) techniques were adopted to for the electrochemical determination of 4-NP after drop casting the NiO nanoparticles onto the screen-printed carbon electrode (SPCE). The developed sensor (NiO/SPCE) showed a high sensitivity of 1.055 μA/nM over a wide linearrange from 1 to 10 nM with a detection limit of 0.519 nM for the detection of 4-NP using DPV technique.
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