Synthesis, Characterization, and Photocatalytic Performance of ZnO–Graphene Nanocomposites: A Review

Development of an efficient electrochemical sensing platform based on ter-poly(luminol-o-anisidine-o-toluidine)/ZnO/GNPs nanocomposites for the detection of antimony (Sb3+) ions

A poly(luminol-o-anisidine-o-toluidine) terpolymer was synthesized, characterized, and modified with GNPs and ZnO NPs. The nanocomposites were then examined for their electroactivity and potential use as cationic electrochemical sensors for detecting Sb3+ ions in phosphate buffer on the surface of a glassy carbon electrode (GCE). Among the different compositions and the terpolymer, the GCE adapted with the PLAT/ZnO/GNPs-5% nanocomposite displayed the highest current response. The fabricated nanocomposite sensor exhibited high sensitivity, with a value of 21.4177 μA μM-1 cm-2, and a low detection limit of 95.42 pM. The analytical performance of the sensor was evaluated over the linear dynamic range (LDR) of 0.1 nM to 0.01 mM. The proposed sensor is effective in detecting and measuring carcinogenic Sb3+ ions in real environmental samples using an electrochemical approach, making it a promising tool for environmental monitoring.

Study of graphene incorporation into ZnO-PVA nanocomposites modified electrode for sensitive detection of cadmium

The presence of heavy metals often causes significant health risks, particularly cadmium, which is known for its high toxicity. In this study, a glassy carbon electrode was successfully modified by incorporating ZnO-PVA-Graphene nanocomposite, leveraging the excellent electrical properties and electron mobility of the material. Comprehensive material analysis, including XRD, confirmed that ZnO maintained its hexagonal wurtzite crystal structure despite the addition of graphene. Moreover, FESEM analysis showed that increasing graphene concentration led to a reduction in ZnO particle size by 85, 68, and 52 nm, respectively, accompanied by a decrease in band gap energy, as verified by UV-Vis measurements. Photoluminescence tests were also conducted and the result showed a noticeable blue shift in ZnO-PVA-Graphene nanocomposites compared to ZnO-PVA, specifically in the near band-edge (NBE) UV emission within the 374-379 nm wavelength range. Through I-V characterization, the optimal graphene concentration for cadmium detection was identified as 1.5 wt% in ZnO-PVA-Graphene nanocomposites, showing an approximate ohmic response. Meanwhile, square-wave voltammetry analysis of cadmium concentrations ranging from 0 to 80 ppm produced a coefficient of determination of 0.98926 and a Limit of Detection (LOD) of 9.88 ppm. These results showed the significant potential of ZnO-PVA-Graphene nanocomposites as a promising material for further development as an effective electrode modifier, enhancing the sensitivity of detection systems.

Architecture design of TiO2 with Co-doped CdS quantum dots photoelectrode for water splitting

Photoelectrochemical hydrogen production is a critical key to solving the carbon-zero goal of countries due to renewable sources of solar light and combustion products of hydrogen-only water. Here, an architecture design for an n-type nano rosettes-rod TiO2 (RT) surface using CdS and Co-doped CdS quantum dots (QDs) is carried out utilizing the SILAR (simple ionic layer adsorption and reaction) method. Furthermore, the photocatalytic behaviour of Co-doped CdS QDs SILAR cycles deposition is investigated in various cycles, including 5, 8, 10, and 12. The FESEM, Raman XRD, Uv-Vis spectrometer, and vibration modes are used to evaluate the photoelectrode surface structure, crystal structure, and solar light absorption, respectively. FESEM images and XRD pattern revealed successive CdS QDS and Co-doped CdS QDs deposition on the RT boundary and rising SILAR cycles of Co-doped CdS QDs lead to further coverage of RT surface. UV-vis spectrometer indicated shifting solar light absorption to the visible region by applying more SILAR cycles of Co-doped CdS QDs deposition. The electrochemical parameters obtained from EIS showed total polarization resistance (Rp) of the RT electrode dramatically decreased with 10 SILAR cycle Co-doped CdS QDs deposition (5093 Ω cm2 and 617 Ω cm2). Linear sweep voltammetry (LSV) and chronoamperometric photocatalytic performance measurements indicated Co-doped CdS QDs on RT extremely enhanced photoresponse under solar irradiation and 10 SILAR cycle Co-doped CdS QDs improved photocurrent density about fourfold according to blank RT electrode.

Fluorosensing of benzaldehydes by CuI-graphene: A spectroscopy, thermodynamics and docking supported phenomenon

Benzaldehyde and 4-methyl benzaldehyde constitute a major part of the harmful volatile organic compounds (VOCs) found in the environment. Hence, rapid and selective detection of benzaldehyde derivatives are required to minimize the environmental degradation as well as the potential hazards on human health. In this study, the surface of the graphene nanoplatelets were functionalized with CuI nanoparticles for specific and selective detection of benzaldehyde derivatives by fluorescence spectroscopy. CuI-Gr nanoparticles exhibited higher efficiency towards the detection of benzaldehyde derivatives as compared to pristine CuI nanoparticles with detection limit (LOD) 2 ppm and 6 ppm for benzaldehyde and 4-methyl benzaldehyde respectively in aqueous medium. The LOD values for the detection of benzaldehyde and 4-methyl benzaldehyde by pristine CuI nanoparticles were poor and found to be 11 ppm and 15 ppm respectively. Fluorescence intensity of CuI-Gr nanoparticles were found to be quenched with increasing concentration (0-0.01 mg/mL) of the benzaldehyde and 4-methyl benzaldehyde. This novel graphene-based sensor was also found to be highly selective for the benzaldehyde derivatives as no changes in signal were detected in presence of other VOCs like formaldehyde and acetaldehyde.

Conducting polymers/zinc oxide-based photocatalysts for environmental remediation: a review

The accessibility to clean water is essential for humans, yet nearly 250 million people die yearly due to contamination by cholera, dysentery, arsenicosis, hepatitis A, polio, typhoid fever, schistosomiasis, malaria, and lead poisoning, according to the World Health Organization. Therefore, advanced materials and techniques are needed to remove contaminants. Here, we review nanohybrids combining conducting polymers and zinc oxide for the photocatalytic purification of waters, with focus on in situ polymerization, template synthesis, sol-gel method, and mixing of semiconductors. Advantages include less corrosion of zinc oxide, less charge recombination and more visible light absorption, up to 53%.