Zinc Oxide Nanoparticle‐modified Glassy Carbon Electrode as a Highly Sensitive Electrochemical Sensor for the Detection of Caffeine

Abstract

Zinc oxide nanoparticles (ZnO NPs) were prepared by a simple, convenient, and cost‐effective wet chemical method using the biopolymer starch. The prepared ZnO NPs were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), energy‐dispersive X‐ray (EDX), Fourier transform infrared (FT‐IR), and UV‐visible spectroscopic techniques. The average crystallite size calculated from XRD data using the Debye–Scherer equation was found to be 15 nm. The electrochemical behavior of caffeine (CAF) was studied using a glassy carbon electrode (GCE) modified with zinc oxide nanoparticles by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Compared to unmodified GCE, ZnO NPs‐modified GCE (ZnO NPs MGCE) exhibited excellent electrocatalytic activity towards CAF oxidation, which was evident from the increase in the peak current and decrease in the peak potential. Electrochemical impedance study suggested that the charge‐transfer capacity of GCE was significantly enhanced by ZnO NPs. The linear response of the peak current on the concentrations of CAF was in the range 2–100 μM. The detection limit was found to be 0.038 μM. The proposed sensor was successfully employed for the determination of CAF in commercial beverage samples.

Ultrasound-Assisted Rapid ZIF-8 Synthesis, Porous ZnO Preparation by Heating ZIF-8, and Their Photocatalytic Activity

“…As a result, the following study focuses on the Z-660-(5 h) sample. As can be seen in Figure 7(a), no typical absorption bands for meIm are observed; instead, the absorption band at 400-550 cm -1 corresponding to the stretching vibration of Zn-O [17,21,31] confirms the formation of ZnO. This result is consistent with that of X-ray diffraction shown in Figure 5(b).…”

“…Zinc oxide (ZnO) is an n-type semiconductor with a wide bandgap (3.37 eV) and a large excitation binding energy (60 meV) at room temperature [21][22][23][24][25]. This material has unique electrical and photovoltaic properties, so it has been studied and applied in the fields of photocatalysis, gas sensing, medicine, electrochemistry, and solar cells [21][22][23][24][26][27][28][29][30][31][32]ZnO has extremely rich morphologies, depending on the synthesis method, such as spheres [27,30], nanorods [28], nanowires [29], and flower-shaped nano [32].…”

A novel highly selective electrochemical chlorobenzene sensor based on ternary oxide RuO2/ZnO/TiO2 nanocomposites

“…19 Among the EC methods, the electrochemical approach has drawn signicant attention of researchers due to its high sensitivity, good selectivity, inexpensive instruments, ease of operation, simple pretreatment of samples, and faster analysis. To improve the sensitivity and avoid the multi-selectivity, the electrodes have been modied with various semi-conductive metal oxides such as ZnO, [20][21][22] Cr 2 O 3 , 23 SnO 2 , 24 WO 3 , 25 and Co 3 O 4 to detect numerous toxic chemicals and biochemicals. 26 In the recent years, few research studies based on semi-conductive metal oxides have been reported for the reliable detection of CBZs.…”

Green synthesis of caffeine based on methylating reagent dimethyl carbonate and environmental friendly separating method

“…Nowadays, the solvent extraction method is generally adopted for the separation of caffeine and by‐product salt in industrial production . Chloroform is an effective extractant, but it is volatile in use, resulting in a significant loss per year and also affecting the health of practitioners.…”