ZnO Quantum Research Articles

Synthesis, characterization and antimicrobial activity of ZnO-QDs @ bis MPA polyester-64-hydroxyl dendrimer nanostructures

This study presents successful synthesis and characterization of five novel Zinc Oxide Quantum Dots @ bis MPA polyester-64-hydroxyl dendrimer nanostructures with tuneable hydrophilicity. The unique feature of these ZnO Quantum...

ZnO quantum dots decorated on graphene oxide and graphene nanoplatelets: Comparison the structure and sensing properties

In this study, we successfully synthesized ZnO quantum dots decorated on graphene oxide (GO) and graphene nanoplatelets (GNP) using a simple hydrothermal method. The synthesized ZnO/GO and ZnO/GNP nanocomposites were thoroughly characterized using various techniques, including X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), Raman and photoluminescence spectroscopies, Transmission electron microscopy (TEM), and Brunauer–Emmett–Teller analysis (BET). We further evaluated the gas sensing capabilities of the synthesized samples. Excitingly, our results demonstrated that the ZnO/GNP sensor exhibited significantly enhanced gas sensing performance for ethylene glycol compared to both the ZnO/GO and pure ZnO sensors. Specifically, at 280 °C, the ZnO/GNP nanocomposite sensor displayed impressive responses of approximately 51 and 183 towards 50 ppm and 200 ppm ethylene glycol, respectively. Moreover, the ZnO/GNP sensor exhibited exceptional selectivity in detecting ethylene glycol. These findings suggest that ZnO quantum dots decorated on commercial graphene nanoplatelets could be a promising candidate for highly sensitive ethylene glycol gas sensors.

Efficient delivery of methotrexate to MDA-MB-231 breast cancer cells by a pH-responsive ZnO nanocarrier

Methotrexate (MTX), an efficient chemotherapy medication is used in treating various malignancies. However, the breast cancer cell line MDA-MB-231 has developed resistance to it due to low levels of the MTX transport protein, and reduced folate carrier (RFC), making it less effective against these cancer cells. Here we designed a very simple, biocompatible, and non-toxic amine-capped ZnO quantum dots to overcome the MTX resistance on the MDA-MB-231 breast cancer cell line. The QD was characterized by HRTEM, DLS EDX, FT-IR, UV–Vis, and Fluorescence spectroscopy. MTX loading onto the QD was confirmed through fluorescence and UV–Vis spectroscopy. Additionally, extensive confocal microscopic investigations were carried out to determine whether the MTX was successfully released on the MDA-MB-231 cell line. It was discovered that QD is a better pH-responsive delivery system than the previous ones because it successfully delivers MTX to the MDA-MB-231 at a higher rate on an acidic pH than it does at a physiological pH. QD also has anticancer activity and can eradicate cancer cells on its own. These factors make the QD to be an effective pH-responsive delivery system that can improve the efficacy of the medication in therapeutic diagnosis.

A solid-phase fluorescence sensor for measuring chemical species in water

In this study, the first of its kind, a solid-phase fluorescence sensing platform was developed to quantify contaminants in water. ZnO quantum dots (QDs) were combined with molecularly imprinted polymers (MIPs) to form fluorescence sensing materials. Solid sensing layers were formed via a straightforward spin-coating method, which demonstrated a strong attachment to the sensor substrate while maintaining the integrity of the sensing materials. The developed sensing platform comprised a portable fluorescence detector to measure fluorescence intensity, instead of traditional fluorescence spectroscopy. The solid sensing platform was first tested with 2,4-dichlorophenoxyacetic acid (2,4-D), demonstrating high sensitivity (0.0233) and a very strong correlation (0.98) between the target molecule concentration and sensor signal. Further, the sensing platform was successfully adapted to measure a substance with a different molecular mass and chemical structure, the algae toxin microcystin-LR (MCLR); this demonstrated the sensor's versatility in quantifying target molecules. Tap water samples spiked with MCLR were also used to test the sensor's practical application. Finally, the working mechanism of the sensing platform was established, and the key information for using the sensor to measure various contaminants was determined. With its high performance, broad applicability, and ease of use, the developed platform provides a suitable basis for lab-on-chip image-based sensing devices for environmental monitoring.

Effect of surface ligands on the photoinduced electron transfer rate and efficiency in ZnO quantum dots and graphene oxide assemblies.

Apart from biocompatibility, ZnO quantum dots (QDs) are considered to be an efficient luminescence material due to their low cost and high redox potential. Here, we report the synthesis of ZnO QDs by using five different functionalizing ligands like mercaptoacetic acid (MAA), 3-mercaptopropionic acid (MPA), octadecene (ODE), ethylene glycol (EG), and oleyl amine (OLA) and fabricate their assemblies with graphene oxide (GO). We investigate the role of functionalizing ligands as a surface modifier of ZnO QDs for their attachment to GO. The steady-state photoluminescence (SSPL) and time-resolved photoluminescence (TRPL) analyses demonstrate the photoluminescence (PL) quenching of ZnO QDs in ZnO QDs-GO assembly. The highest reduction in PL intensity is observed with ZnO QDs-GO assembly with EG as a surface functionalizing ligand. Cyclic voltammetry (CV) analysis confirms the feasibility of charge transfer from ZnO QDs to the GO. The maximum (79.43%) charge transfer efficiency (ECT) is observed in the case of ZnO-MAA-GO as compared to other assemblies. This means the thiol group-containing ligands facilitate charge transfer as compared to hydroxyl and amine group ligands. This leads to the conclusion that charge transfer in ZnO QDs-GO assemblies depends strongly on the nature of surface ligands.

ZnO quantum dots sensitized ZnSnO3 for highly formaldehyde sensing at a low temperature

Developing gas sensors for formaldehyde vapor detection is necessary. Metal oxide semiconductor (MOS) exhibited good formaldehyde sensing properties but with high working temperature and unsatisfactory selectivity. Herein, ZnSnO3 was sensitized by ZnO QDs modification for high-performance formaldehyde sensing at low working temperatures via simple immersion method. Meanwhile, SnO2 QDs instead of ZnO QDs was also modified on ZnSnO3 nanocubes. The result indicated both ZnO QDs and SnO2 QDs modification greatly improved gas sensing response and lower the working temperature of ZnSnO3 to formaldehyde. Whereas, the obtained ZnSnO3/ZnO QDs composite (ZSO/ZQD) containing 5 wt% ZnO QDs (ZSO/ZQD-0.05) showed a highest response value of 613.3–100 ppm formaldehyde at 70℃ with good reversibility and stability, which was nearly 20 times of bare ZnSnO3 and 6 times of SnO2 QDs modified ZnSnO3. The detection limit reached 100 ppb formaldehyde. The formaldehyde sensing performance of ZSO/ZQD-0.05 composite was checked in presence of simulated indoor pollutants. Its improved sensor performance was mainly attributed to ZnO QDs, which played roles in forming rich heterojunctions with ZnSnO3, increasing the surface area, and providing oxygen deficiency for formaldehyde sensing reaction. This provided an alternative way to improving the sensing properties of MOS by QDs modification.

Controllable terahertz intersubband absorptions in ZnO/(Sb,N) co-doped ZnO quantum wells: First-principles study

ZnO-based heterostructures have emerged as promising materials for infrared and terahertz (THz) optoelectronic technologies capable of operating at room temperatures. This is attributed to the intrinsically high longitudinal-optical (LO) phonon energy which suppresses the phonon scattering to boost the temperature performance. Numerous high-performance THz sources rely on single doping (e.g., ZnO/MgxZn1–xO, ZnO/CdxZn1–xO hybrids). Herein, the combined theoretical approaches based on density functional theory (DFT) and the numerical matrix method were employed to unravel the electronic and optical properties of a quantum well made from ZnO/(Sb,N) co-doped ZnO heterostructures. The findings reveal that (Sb,N) co-doped relatively requires the lower formation energy than the single doping counterparts. Both un-doped and (Sb,N) co-doped ZnO are characterized as semiconductors of which the energy gap of the latter is relatively lower. The combination of these materials consequently creates type-I band lineups with the valence and conduction band offsets of 1.03 eV and 0.61 eV, respectively. Intriguingly, a confined electron in the resultant quantum well derived from the conduction band offset exhibits the intersubband optical transitions in the energy range of 6.0–10.0 THz which is the challenging regime in THz technology. Moreover, the optical absorptions can be effectively modulated by the width of the quantum well and the external electric fields. Specifically, the increases in the well width and field strength result in the redshift and blueshift in the absorption spectrum, respectively. Hence, ZnO/(Sb,N) co-doped ZnO/ZnO heterostructure is conclusively a potential candidate for THz optoelectronic devices.

Waterborne epoxy composite coating with long-term corrosion resistance through synergy of MXene nanosheets and ZnO quantum dots

Two-dimensional (2D) MXene nanosheets have emerged as a promising candidate as functional filler for anticorrosion coating. However, the self-stacking of MXene nanosheets and high conductivity limited the long-term anticorrosion ability of the coating. Herein, the ZnO quantum dots (ZnO QDs) decorated MXene hybrid was prepared via electrostatic assembly, which was modified by aminosilane-functionalized with 3-aminopropyltriethoxysilane (ATPES) and used as functional filler for reinforcing the waterborne epoxy coating (WEP) via simple spraying technique. Benefiting from the improved dispersion and synergy of ZnO QDs and MXene nanosheets, the WEP coating exhibited favorable anticorrosion performance. For 0.50 wt% F-MXene@ZnO QDs/WEP composite coating, the impedance remained 1.25 × 108 Ω cm2 (0.01 Hz) after immersing in 3.5 wt% NaCl medium for 30 days, which was three orders of magnitude higher than pure WEP. The EDS analysis and salt spray test strongly supported the long-term corrosion resistance of WEP composite coating. Furthermore, the reasonable anti-corrosion performance of composite coating including the physical barrier and charge neutralization effect was illustrated. This work expands the 2D MXene as a functional filler for enhancing the anticorrosion ability of waterborne epoxy coating.

Templated synthesis of ZnO quantum dots via double solvents method inside MOF-801 as emerging photocatalyst for photodegradation of Acid Blue 25 under UV light

Templated synthesis of ZnO quantum dots (QDs) is one of the most important techniques for controlled synthesis of it without need of surfactants and advanced laboratory equipment. MOF-801 was used as a template for the synthesis of ZnO QDs with controlled shape and size. The “ship-in-a-bottle” approach was applied for templated synthesis of ZnO QDs into the MOF-801 porous matrix via double solvents method (DSM) combined with an in situ reduction route (ISRR). The formation of ZnO QDs inside MOF-801 template was monitored by PXRD, FT-IR, EDX, ICP-OES, XPS, BET, TEM, DRS, PL, EIS, and Mott − Schottky analyses. The ZnOQDs@MOF-801 nanocomposite as emerging photocatalyst exhibited better photocatalytic performance for degradation of Acid Blue 25 with a rate constant of 0.00179 min−1 which is 2.35 higher than MOF-801 (0.00076 min−1) under UV irradiation, due to ZnO QDs embedded inside MOF-801 template. The unique properties of ZnO QDs, including quantum confinement, multiple exciton generation, and efficient separation of charge carriers through decrease in electron-hole recombination at the quantum scale, contribute to the photocatalytic degradation of Acid Blue 25.

Ternary mixed crystal effects on optical phonons in wurtzite ZnO quantum wells with asymmetric MgZnO barriers

Optical phonons significantly relate to fundamental limits on dynamical processes in layered polar semiconductor devices. MgZnO layers commonly serve as barriers of ZnO quantum wells (QWs) to improve the electric and optical properties by quantum confinement while keeping the Mg fraction below 0.4 to avoid the crystal phase transformation from wurtzite to rocksalt. This work investigates ternary mixed crystal effects on optical phonons in wurtzite ZnO quantum well with asymmetric barriers of MgxZn1-xO and MgyZn1-yO over a full range of Mg mole fractions. Since MgZnO could be wurtzite (WZ) and rocksalt (RS) phases, the QWs can be denoted as WZ/WZ/WZ, WZ/WZ/RS, and RS/WZ/RS, respectively. Both asymmetries in the Mg fractions and crystal structures of the two barriers affect the optical phonons in QWs. RS/RS/RS quantum wells are also discussed for comparison. Since oscillatoring electrostatic potential of optical phonons is only permitted in the anisotropic wurtzite but forbidden in istropic rocksalt, more modes of confined optical phonons are found in a WZ/WZ/WZ QW, followed by WZ/WZ/RS one, and the least in the RS/WZ/RS one, while there is no confined optical phonons in RS/RS/RS quantum wells. Besides, the difference between the Mg fractions in two barriers leads to more modes of interface optical phonons due to the two unequal interfaces. The modes contained in the optical phonons spectra as well as their frequency ranges, dispersion relations, and electrostatic potentials, vary with Mg fraction in barriers. The strain on interfaces induced by the lattice mismatch leads to a slight blue shift of the dispersion relation as Mg fraction increases. Based on the results of this paper, the optical phonons related to electronic and optoelectronic properties in QWs could be further understood and adjusted.

Size-Controlled ZnO Nanoparticles Synthesized with Thioacetamide and Formation of ZnS Quantum Dots

In this work, we report the first attempt to investigate the dependence of thioacetamide (TAA) on the size of ZnO nanoparticles (NPs) in forming ZnS nanostructures from ZnO. Size-controlled B(blue)_, G(green)_, and Y(yellow)_ZnO quantum dots (QDs) and NC (nanocrystalline)_ZnO NPs were synthesized using a sol–gel process and a hydrothermal method, respectively, and then reacted with an ethanolic TAA solution as a sulfur source. ZnO QDs/NPs began to decompose into ZnS QDs through a reaction with TAA for 5~10 min, so rather than forming a composite of ZnO/ZnS, ZnO QDs and ZnS QDs were separated and remained in a mixed state. At last, ZnO QDs/NPs were completely decomposed into ZnS QDs after a reaction with TAA for 1 h irrespective of the size of ZnO QDs up to ~50 nm. All results indicate that ZnS formation is due to direct crystal growth and/or the chemical conversion of ZnO to ZnS.

ZnO Quantum Photoinitiators as an All-in-One Solution for Multifunctional Photopolymer Nanocomposites.

Nanocomposites are constructed from a matrix material combined with dispersed nanosized filler particles. Such a combination yields a powerful ability to tailor the desired mechanical, optical, electrical, thermodynamic, and antimicrobial material properties. Colloidal semiconductor nanocrystals (SCNCs) are exciting potential fillers, as they display size-, shape-, and composition-controlled properties and are easily embedded in diverse matrices. Here we present their role as quantum photoinitiators (QPIs) in acrylate-based polymer, where they act as a catalytic radical initiator and endow the system with mechanical, photocatalytic, and antimicrobial properties. By utilizing ZnO nanorods (NRs) as QPIs, we were able to increase the tensile strength and elongation at break of poly(ethylene glycol) diacrylate (PEGDA) hydrogels by up to 85%, unlike the use of the same ZnO NRs acting merely as fillers. Simultaneously, we endowed the PEGDA hydrogels with post-polymerization photocatalytic and antimicrobial activities and showed their ability to decompose methylene blue and significantly eradicate antibiotic-resistant bacteria and viral pathogens. Moreover, we demonstrate two fabrication showcase methods, traditional molding and digital light processing printing, that can yield hydrogels with complex architectures. These results position SCNC-based systems as promising candidates to act as all-in-one photoinitiators and fillers in nanocomposites for diverse biomedical applications, where specific and purpose-oriented characteristics are required.

Nanoscale ZnO Improves the Amino Acids and Lipids in Tomato Fruits and the Subsequent Assimilation in a Simulated Human Gastrointestinal Tract Model.

With the widespread use of nanoenabled agrochemicals, it is essential to evaluate the food safety of nanomaterials (NMs)-treated vegetable crops in full life cycle studies as well as their potential impacts on human health. Tomato seedlings were foliarly sprayed with 50 mg/L ZnO NMs, including ZnO quantum dots (QDs) and ZnO nanoparticles once per week over 11 weeks. The foliar sprayed ZnO QDs increased fruit dry weight and yield per plant by 39.1% and 24.9, respectively. It also significantly increased the lycopene, amino acids, Zn, B, and Fe in tomato fruits by 40.5%, 15.1%, 44.5%, 76.2%, and 12.8%, respectively. The tomato fruit metabolome of tomatoes showed that ZnO NMs upregulated the biosynthesis of unsaturated fatty acids and sphingolipid metabolism and elevated the levels of linoleic and arachidonic acids. The ZnO NMs-treated tomato fruits were then digested in a human gastrointestinal tract model. The results of essential mineral release suggested that the ZnO QDs treatment increased the bioaccessibility of K, Zn, and Cu by 14.8-35.1% relative to the control. Additionally, both types of ZnO NMs had no negative impact on the α-amylase, pepsin, and trypsin activities. The digested fruit metabolome in the intestinal fluid demonstrated that ZnO NMs did not interfere with the normal process of human digestion. Importantly, ZnO NMs treatments increased the glycerophospholipids, carbohydrates, amino acids, and peptides in the intestinal fluids of tomato fruits. This study suggests that nanoscale Zn can be potentially used to increase the nutritional value of vegetable crops and can be an important tool to sustainably increase food quality and security.

Photocatalytic research performance of zinc oxide/graphite phase carbon nitride catalyst and its application in environment

Abstract In this article, ZnO quantum dots (QDs)-g-C3N4 complexes were prepared by a combined sol–gel method and ultrasound-assisted chemical method, and ZnO-g-C3N4 composites with different doping ratios were also prepared for photocatalytic degradation of dye wastewater. The composites were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffractometry, Fourier transform infrared, X-ray photoelectron spectroscopy, diffuse reflectance spectroscopy, and photoluminescence. The photocatalytic performance of the best ZnO QDs-g-C3N4 complexes with different g-C3N4 doping amounts was investigated, and the kinetics of their photocatalytic reactions were analyzed, and it was found that the best effect of ZnO-g-C3N4 10% could reach 89.08% and ZnO QDs-g-C3N4 could reach 91.53%. It was also demonstrated that ZnO-g-C3N4 10%, ZnO QDs-g-C3N4 cyclic stability is better, and the reaction mechanism of ZnO QDs-g-C3N4 was investigated. It can be used for the degradation of dyes in environmental wastewater and the removal of harmful substances from the natural environment.

Tunable and white light photoluminescence from ZnO on porous Si with the addition of carbon quantum dots.

In this work we demonstrate a two-pixel solid-state photoluminescent device able to emit white light covering the entire visible spectrum from 380 nm up to 800 nm. The device is based on a combination of porous Si, hydrothermally grown ZnO and carbon quantum dots, in a two-pixel formation, with porous Si and ZnO acting independently while the carbon quantum dots are deposited on top of the entire device. All processing is done using standard Si processing techniques. Moreover, the device design allows for tunability of the emitted spectrum simply by choosing the desired combination of the materials. Overall, the demonstrated device is low cost, environmentally safe and biocompatible.

A Polycaprolactone-Capped ZnO Quantum Dots-Based Fluorometric Sensor for the Detection of Fe3+ Ions in Seawater.

Fe3+ ion plays a very active role in life, agriculture, and industry. Human health and the environment are seriously affected by the abnormal presence or excess of this cation. Therefore, the development of a fast, reliable, sensitive, and simple fluorescent probe to detect this cation is crucial. In the present paper, polycaprolactone-capped zinc oxide quantum dots were prepared for the determination of Fe3+ ions. The proposed fluorescent chemosensor exhibited a fluorometric and strong quenching effect toward Fe3+ ions at two wavelengths (303 and 602 nm). The limit of detection (LOD) was calculated as 0.410, and 0.333µM at the mentioned wavelengths. Also, the binding stoichiometric ratio was calculated as 1:1 by Job's plot. The findings indicated that the PCL@ZnO colorimetric chemosensor could be successfully applied with reliable, and good accuracy for the detection of Fe3+ ions in real seawater samples.

ZnO quantum dots @ nitrogen and sulfur Co-doped porous carbon nanosheets for the detection of lung cancer biomarkers in exhaled breath

The development of non-selective sensors as an e-nose system for breath analysis application generates unique breath prints delineating the fundamental body metabolism aiding early diagnosis of lung cancer. In this work, size dependent ZnO quantum dots (QDs) were controlled by pH and finely dispersed on nitrogen and sulfur co-doped porous carbon nanosheet (CNS) for exploration of their chemi-resistive gas sensing property. Application of these nanocomposites to different lung cancer biomarkers (toluene, isoprene acetone and benzene) depicts unique responses to each at different operating temperatures. Particularly, the composite with lower ZnO QDs size on sulfur rich porous carbon nanosheet (SC-SQD) exhibited 2.5 times of the response to toluene compared to the composite with higher QDs size and sulfur poor porous carbon nanosheet (NC-LQD) in the concentration range between 1 ppm and 5 ppm. It was demonstrated that for 5 ppm of toluene, a response of 31.4 was observed with a response and recovery time of 18 s and 58 s, respectively. The sensor exhibited an estimated lower limit of detection of 800 ppb. Besides, the sensor exhibited a gradual decrease (∼9.55%) in response to 5 ppm toluene at 90% humidity. This superior performance can be explained by the density of defect states, reactive oxygen species (ROS) and oxidation states of functionalization.

"Off/On” Fluorescent Probe based on Aggregation-Induced Quenching of ZnO-Quantum dots for Determination of Ara-C: Pharmacokinetic Applications, Adsorption Kinetics & Green Profile Assessment

Herein, a turn “Off/On” fluorescence probe based on ZnO quantum dots (ZnO-QDs) has been proposed and successfully utilized for the determination of Ara-C (cytarabine) using ceric ions (Ce4+) as quencher and ethylenediamine (ED) as a linker. The probe is based initially on the quenching effect of Ce4+ ions on the strong native fluorescence of ZnO-QDs forming the Turn Off system (Ce@ZnO-QDs) that believed to occur due to the aggregation-induced quenching (AIQ) mechanism. The second step is the addition of Ara-C in the presence of ethylenediamine (ED) that encourages the formation of Ara-C/ED/Ce4+ as well as the release of the free ZnO-QDs, leading to the recovery of the fluorescence intensity. The developed sensing platform shows a linear response towards Ara-C over the range of 10 to 1000 ng mL−1 giving a limit of detection (LOD) and limit of quantitation (LOQ) of 1.22 ng mL−1 and 3.70 ng mL−1, respectively. A dispersive magnetic solid phase micro-extraction (dMSPE) method was developed and optimized for the extraction of Ara-C in spiked human plasma using thiol-modified magnetite nanoparticles (S-MNPs). The proposed platform exhibits good sensitivity toward Ara-C in the presence of different interfering substances. Excellent recoveries are obtained after spiking different concentrations of Ara-C into rabbit plasma samples. The validated experimental parameters have been successfully applied to monitor the pharmacokinetic profile of Ara-C in rabbit plasma. A detailed adsorption kinetics study has been carried out to provide a deep insight into the adsorption behavior of Ara-C on the thiol-doped-magnetite nanoparticles. The greenness assessment of the proposed method was achieved and compared with other reported methods using two tools of greenness; the green analytical procedure index (GAPI) and the analytical greenness calculator AGREE.

ZnO QDs/GO/g-C3N4 Preparation and Photocatalytic Properties of Composites.

Using an ultrasound-assisted chemical technique, ZnO quantum dot and ZnO composites were created. The optical characteristics and structural details of these composites were examined using TEM, XRD, XPS, FT-IR, UV-vis, and BET. The results revealed that both the ZnO quantum dot composite and ZnO composite exhibited outstanding optical properties, making them suitable for photocatalytic reactions. In order to analyze the photocatalytic performance, a degradation experiment was conducted using Rhodamine B solution as the simulation dye wastewater. The experiment demonstrated that the degradation of Rhodamine B followed the first-order reaction kinetics equation when combined with the photocatalytic reaction kinetics. Moreover, through cyclic stability testing, it was determined that the ZnO QDs-GO-g-C3N4 composite sample showed good stability and could be reused. The degradation rates of Rhodamine B solution using ZnO-GO-g-C3N4 and ZnO QDs-GO-g-C3N4 reached 95.25% and 97.16%, respectively. Furthermore, free-radical-trapping experiments confirmed that ·O2- was the main active species in the catalytic system and its photocatalytic mechanism was elucidated. The photocatalytic oxidation of ZnO quantum dots in this study has important reference value and provides a new idea for the subsequent research.

Graphene oxide/ZnO nanocomposites applied in photocatalysis of dyes: Tailoring aqueous stability of quantum dots

Nanocomposites between ZnO Quantum Dots (QDs) and Graphene Oxide (GO) were synthesized by sol-gel method in isopropanol. The proportion of GO aqueous dispersion was evaluated and ZnO QDs were also prepared with addition of water, for comparison. Indeed, the GO or water addition had a huge impact in the ZnO QDs size and photoluminescence, once the greater the GO/water addition, the greater the ZnO QDs size (from 4.5 ± 0.1–23.8 ± 0.4 nm) and the 50 µL of GO (or water) added to the synthesis led to a higher intensity emission. The photocatalytic activity of the ZnO-based materials was evaluated for methylene blue (MB) and astrazon blue (AB) degradation in isopropanol and water using two different sources of light irradiation (fluorescence and Hg vapor lamps). Once again, the GO/water addition affected their photocatalytic behavior and stability in aqueous medium. The ZnO QDs/GO had an impressive photocatalytic performance in both sources of light irradiation in isopropanol and aqueous medium (99% and 93% of degradation after 30 min of irradiation with Hg vapor lamp, respectively). In addition, the photocatalytic activity of this nanocomposite was stable when submitted up to 5 photodegradation cycles and to higher MB concentrations, besides being successfully reused in aqueous medium.