Spherical Dot Research Articles

Chromolaena Odorata Leaves Derived Carbon Dot‐Based Fluorescence/Second‐Order Scattering Ratiometric Sensor for Fe3+ and Vitamin C

Herein, a ratiometric fluorescence and second‐order scattering sensor with plant leaf‐derived carbon dots (CDs) for Fe3+ and vitamin C is reported. The CDs are prepared from Chromolaena odorata leaves through a one‐pot hydrothermal method. The synthesized CDs have a quantum yield of 22.6%. The spherical dots have an average size of 3 nm and the chemical composition is found as nitrogen (7%) being the highest heteroatom present along with carbon and oxygen atoms in it. The ratio between fluorescence intensity at 445 nm and second‐order scattering constitutes the sensor output. A linear relationship is found between the output and analyte concentration in the range 0–70 and 0–10 μM with limit of detection 0.12 and 1.2 μM for Fe3+ and vitamin C, respectively. Static mechanism along with inner filter effect has been identified as the underlying quenching mechanism for Fe3+ activity. The strong chelation of Fe3+ by vitamin C further enhances the fluorescence. The change in the second‐order scattering intensity is explained by the formation and disruption of CDs/Fe3+ complex. The sensor also shows satisfactory performance with borewell water (Fe3+) and commercial tablet (vitamin C) with recovery rate ranging between 98.6% and 103.5%.

Morinda coreia fruits derived green-emissive nitrogen-doped carbon quantum dots: Selective and sensitive detection of ferric ions from water

Carbon quantum dot containing nitrogen has been prepared by utilizing a green biomass resource, Morinda coreia fruits, by a single step hydrothermal procedure. The spherical carbon dots are analysed by HR-TEM, XPS, FT-IR, UV–visible and photoluminescence studies. With a mean diameter of 1.99 nm, they possessed functional groups like carboxyl and amide on their surface and emit light of wavelength of 490 nm under 390 nm excitation. The fluorescent Morinda coreia carbon dots (MCCDs), whose quantum yield is found to be 17.1 %, are very sensitive to the presence of iron (III) ions with a low detection limit of 1.32 μM. Successful fluorometric determination of Fe3+ ions from tap water and borewell water were also achieved with good recovery rates. Interactions between surface groups on MCCDs and Fe3+ ions lead to the formation of a non-fluorescent complex, and a static quenching mechanism is proposed.

Garrett approximation for quantum dots

An approximation previously proposed by Garrett to evaluate the en- ergy level of a particle in a finite square well using the expression of the corresponding level in an infinite one is extended to a spherical well. In this way, simple analytical approximations are obtained for the energy levels of a particle in a spherical cavity with penetrable walls, knowing the exact values of the corresponding levels in a similar cav- ity, with impenetrable walls. The relative errors of this approximation are of order of about 10−3. This approach can be extended to slightly deformed spherical dots (ellip- soidal dots with a small eccentricity), with interesting applications in nanophysics and nanotechnology.

Simultaneous sensing of strain and temperature based on the inline-MZI embedded point-shaped taper structure with low crosstalk.

An embedded spherical dot taper structure (EDT) based on the MZI principle is proposed in this paper, which is mainly fabricated by using two special arc discharges in the preparation process. The proposed structure involves two specialized arc discharge techniques. First, an oversaturated discharge fusion process creates a micro-arc spherical area on the fiber end face to form the first link type. Second, an unsaturated discharge-pulling taper fusion joint creates a local micro-extrusion operation on this micro-arc fiber end face to form the second link. The thermal stress from instantaneous discharge causes a reverse spherical expansion zone to form in the end face structure, similar to the micromachining of long-period fiber gratings that use local CO2 laser etching to create modulated zones. The study involves a mathematical and theoretical analysis of how geometric parameters in the spherical modulation zone impact the structure's characteristic spectrum. The research demonstrates the potential for this structure to function as a light-intensity modulated strain sensor device through both theoretical and experimental means. As per the experimental findings, the optimized structure displays a high level of strain sensing sensitivity at 0.03 dB/µε and temperature sensing sensitivity of 73 pm/°C (20°C-75°C) and 169 pm/°C (75°C-120°C). Additionally, it possesses excellent cross-sensitivity at only ∼0.0015 µε/°C. Therefore, this sensor presents a favorable option for strain and temperature synchronization sensing and monitoring components, and exhibits notable application prospects in precision engineering, which encompasses mechanical manufacturing, the power and electrical industry, healthcare domain, and certain specialized areas of small-scale precision engineering.

Silver nanoparticles-based thioureidophosphonate composites: Synthesis approach and their exploitation in 4-nitrophenol reduction

Two novel mono- and bis-thioureidophosphonate cores (referred by MTP & BTP, respectively) were facilely synthesized in ionic liquid conditions and incorporated with silver nanoparticles (Ag NPs) via in-situ reduction method giving two heterogeneous nanocatalysts, denoted as Ag NP/MTP and Ag NP/BTP, respectively. X-ray diffraction (XRD), ultraviolet-visible (UV–Vis), and high-resolution transmission electron microscopy (HR-TEM) tools were conducted for the as-fabricated Ag NP/TP nanocomposites revealing the good dispersion of Ag NPs in spherical black dots with average size ranges of (∼9.5–12.7 nm) and (∼17.0–22.5 nm) for Ag NP/MTP and Ag NP/BTP, respectively. The Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) techniques clarified that, MTP possessing (POPh, PO, C=S, HCO, and >NH) functionalities were participated in the reduction of Ag+ ions to Ag0 NPs. The catalytic properties of both Ag NP/TP nanocomposites were verified through the chemical conversion of 4-nitrophenol (4-NP) to less hazardous 4-aminophenol (4-AP) comparable to the slight catalytic reduction of Ag NPs-free TP derivatives. To assess the catalytic performance, some kinetic parameters such as rate constant (Kapp), normalized rate constant (Knor), and turnover frequency (TOF) were estimated at the highest concentration of 4-NP. Accordingly, Ag NP/MTP exhibited more remarkable catalytic activity and durability toward 4-NP reduction than that of Ag NP/BTP. The simple stereochemistry and accessibility of active sites for MTP tuned the surface function with Ag+ ions, affording more stable and regular Ag NPs over the same nanoparticle with BTP. Regarding Ag NP/MTP, catalytic improvement rates to 69%, 64%, and 69% were respectively recorded for Kapp, Knor, and TOF over Ag NP/BTP. Moreover, both nanocatalysts demonstrated good surficial stability through 10 consecutive cycles. Herein, this study has provided a new sustainable route for developing new TP-wrapped metal nanocomposites as robust and selective platforms in catalytic and environmental applications.

Biomass derived nitrogen functionalized carbon nanodots for nanomolar determination of levofloxacin in pharmaceutical and water samples.

Binder-free and efficient electrochemical sensing of levofloxacin (LF) was successfully developed based on the nitrogen-doped carbon nanodots (NCNDs). The NCNDs were synthesized by hydrothermal carbonation (180°C for 12 h), and the heteroatom was embedded in aqueous solution of ammonia (NH3). Spectral and microscopic characteristization techniques were used to analyze the topological, crystallinity, and chemical binding behavior of synthesized biomass functional material. HR-TEM image revealed a uniform spherical dot (2.96 nm), and superior quantum yield efficiency (0.42 Φ). The NCNDs was drop coated on a glassy carbon electrode (GCE) and electrochemical sensing of LF was performedby cyclic voltammetry (CV), differential pulse voltammetry (DPV), and amperometric i-t curve in phosphate-buffered saline (PBS; pH = 7.0). The NCNDs modified electrode showed a sharp oxidation peak at +0.95 V (vs. Ag/AgCl) with a four-fold higher current response than the bareGC electrode. The NCNDs/GCE surface not only increases the current response, but has lower detection potential, and facilitates electron transfer reaction. Under optimized working parameters, the NCNDs/GCE showed wide linear concentrations rangefrom 200 nM to 2.8 mM and a low detection limit (LOD) of 48.26 nM (S/N = 3). The electrode modified with NCNDs has high electrochemical sensing stability (RSD = 1.284 ± 0.05% over 5 days), and superior reproducibility (RSD = 1.682 ± 0.06% (n = 3)). Finally, theNCNDs modified GC electrode was successfully applied to quantify the concentration of LF in drug and river water samples with acceptable recovery percentages of 96.60-99.20% and 97.20-99.00% (n=3), respectively.

On how zeolitic imidazolate framework-8 reduces silver ion release and affects cytotoxicity and antimicrobial properties of AgNPs@ZIF8 nanocomposite

For the first time, this study compared three types of Ag-doped ZIF-8 nanocomposites (AgNPs@ZIF-8(α), AgNPs@ZIF-8(β), and APTES-functionalized AgNPs@ZIF-8(γ)), besides ZIF-8 and APTES@ZIF-8. The composites were characterized in terms of morphology and crystalline structure, encapsulation capacity, capability to keep silver, antibacterial activity against E. coli and S. aureus, and cytotoxicity to human skin fibroblast (HSK) cell line. TEM analysis showed spherical dots of AgNPs (< 10 nm) on the surface or in matrix of ZIF-8 particles, and also their XPS spectra displayed two peaks corresponding to Ag 3d3/2 and Ag 3d5/2. FTIR analysis confirmed a successful chemical interaction between APTES and ZIF-8 in AgNPs@ZIF-8(γ). All of the nanocomposites displayed a combination of microporosity (<2 nm) and mesoporosity (2–50 nm) structures. BET analysis showed a specific surface area of 1718.5 m2/g for ZIF-8, whereas the amine-functionalized particles (i.e., APTES@ZIF-8 and AgNPs@ZIF-8(γ)) showed a decrease of about 1000 m2/g in the surface area and an increase of about 2 times in pore diameter. Different levels of silver were doped into the nanocomposites: AgNPs@ZIF-8(α), 7.04 mg/g; AgNPs@ZIF-8(γ), 27.17 mg/g; and AgNPs@ZIF-8(β), 38.91 mg/g. MTT test on HSK cells revealed IC50 values of 31.4–39 µg/ml for the three Ag-doped ZIF-8 and a higher IC50 (48.2 µg/ml) for ZIF-8. AgNPs@ZIF-8(β) and AgNPs@ZIF-8(γ) displayed MICs of 400 µg/ml and between 400 and 600 µg/ml against both E. coli and S. aureus, and the Ag-doped composites illustrated an Ag-loading content dependency to induce antibacterial activity. Taken together, the findings suggest that AgNPs@ZIF-8 nanocomposites could be introduced as a safer alternative for AgNPs or antibiotics to the health and biomedical industries.

P‐12.7: Front Light Guide Plates for Reflective LCDs

Reflective liquid crystal display has the advantages of energy saving and environmental protection. When the ambient light is low, the front light source is required to provide illumination rays. The front light guide plate has a great influence on display luminance, contrast, etc. Based on Comprehensive considerations on luminance, uniformity, stray light, an analysis and evaluation method for front light guide source is proposed. Taking spherical dots as an example, the influence of dot radius and height on the comprehensive performance of the front light source is analyzed. The simulation results show that when the R:H is 3:1, the comprehensive evaluation parameters of the spherical structure are high, and the signal‐to‐noise ratio is increased by 240%, which can greatly improve the display performance. The analysis and evaluation method proposed in this paper can effectively guide the development of front light guide plates, shorten the development time and reduce the development cost.

Preparation of biomass carbon dots for foam stabilizer of foamed concrete

This paper presents a novel method for preparing an ultra-stable foam based on carbon quantum dots. In this study, carbon quantum dots (RHBCDs) were synthesized using biological waste (rice husk) as carbon source. HRTEM analysis observed the formation of spherical carbon dots with a particle size of no more than 7 nm. The results of FTIR and XPS showed that RHBCDs had good water solubility. XRD analysis confirmed that RHBCDs had typical characteristic peaks of carbon dots. Meanwhile, the performance of foamed concrete prepared by adding RHBCDs to vegetable protein-based surfactant (PS) were studied. The experimental results show that the foams containing RHBCDs have higher density, viscosity and stability. When the addition of RHBCDs was 9.0 wt%, the foam (PS-RS) displacement decreased by 8 % in the first 5 min. PS-RS foam not only reduces the fluidity of foam concrete, but also reduces the hydration exothermic peak of cement. After standard curing, the mechanical properties of foamed concrete increased from 3.38 to 4.64 MPa due to the addition of RHBCDs. And the percentage of pores in the range of 100–500 μm increased to 70.47 %, which means that the addition of RHBCDs not only reduces the pore size distribution and pore size, but also reduces the thermal conductivity. In addition, the shrinkage resistance and homogeneity of foamed concrete have also been improved. In part, one reason is that RHBCDs can be evenly adsorbed on the surface of foam. Another reason is that RHBCDs can fill the pores.

A numerical study of the mechanical and fracture properties of ZTA (zirconia toughened alumina)p/40Cr steel spatial spherical dot matrix composite

In this work, the geometrical characteristics of ZTA reinforcement particles were obtained, and a three-dimensional numerical model of ZTAp/40Cr steel spatial spherical dot matrix composite, similar to the actual structure, was established. In addition, the matrix toughness and shear fracture criterion, the brittle failure criterion of reinforcement particles, and the interfacial traction splitting criterion were all established. Under uniaxial compression, the influence of constitutive factors (volume fraction of spatial spherical dot matrix composite zone - VFB, and particle size - RPS) on the mechanical characteristics and fracture behavior of spatial spherical dot matrix composites was investigated. The elastic modulus, the compressive strength, and elongation in the stress–strain curves were calculated to assess the mechanical properties of the composites, and the particle average Mises stress and particle stress concentration coefficient were introduced to quantify the load carrying capacity of the composites. Furthermore, the fracture behavior of the secondary interface damage, the internal isotropic strain, and the macroscopic failure behavior were used to study the composites' fracture behavior. A new approach and theoretical foundation for following composites conformal design were established.

Gold-selenide quantum dots supported onto cesium ferrite nanocomposites for the efficient degradation of rhodamine B

In this work, different weight percentage of gold-selenide quantum dots (AuSe QDs) (1.0, 2.5, 5.0 and 7.0 wt.%) were successfully synthesized and decorated on cesium ferrite nanocomposite (Cs2Fe2O4 NC). The as-prepared pure AuSe QDs, pure Cs2Fe2O4 NC, and x wt.% AuSe QDs/Cs2Fe2O4 NC photocatalysts were investigated using different characterization techniques such as nitrogen adsorption desorption isotherms (BET), X-ray diffraction patterns (XRD), transmission electron microscopy (TEM), and UV-vis absorption spectroscopy. The results show that AuSe QDs were uniformly distributed on Cs2Fe2O4NCs surface as spherical dots with an average size of 1.0–8.0 nm. While the Cs2Fe2O4 NCs possess an average size between 10 to 35 nm. The photocatalytic performance of x wt. % AuSe QDs/Cs2Fe2O4NCs were measured through the photodegradation of rhodamine B (RhB) dye as a model water pollutant, under a150 W-Mercury lamp with a filter (JB400) as a simulated source of visible light. The results revealed that the % degradation of RhB increased from 50.0 %, 59.1 %, 76.4 %, and to 99.15 % within 150 min for the pure Cs2Fe2O4, 1.0, 2.5 and 5.0 wt.% AuSe QDs/Cs2Fe2O4 NC photocatalysts, respectively. The 5.0 wt.% AuSe/Cs2Fe2O4 NC sample showed highest photocatalytic activity. The effect of recycling also studied. High photocatalytic performance and superior stability confirmed that the prepared nanocomposites act as good photocatalysts.

Green synthesis of water-soluble fluorescent carbon dots from rosemary leaves: Applications in food storage capacity, fingerprint detection, and antibacterial activity

Blue fluorescent carbon dots are synthesized via a one-step hydrothermal method using rosemary leaves as a carbon source. The obtained carbon dots are characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-Vis, FTIR, and fluorescence spectrometry. The results show that carbon dots gave a maximum emission peak at 422 nm when excited at 332 nm. The average particle diameter of the synthesized spherical carbon dots is found to be 16.13 nm with a 4.6-nm standard deviation. The diameters of the produced carbon dots vary, as is evident from standard deviation heights, resulting in multicolor emission spectra. The fruit storage experiment is carried out by investigating the qualitative antioxidant ability of the produced carbon dots. The results obtained for polyvinyl alcohol–carbon dot–coated samples differ remarkably compared to polyvinyl alcohol–coated samples only. The polyvinyl alcohol–carbon dot composition is used in latent fingerprint detection applications. In analyses made on a glass surface, fingerprints cannot be monitored on the glass surface with the polyvinyl alcohol layer under ultraviolet light, while they are observed on the surface covered with the polyvinyl alcohol–carbon dot composition. Moreover, biological activity against Gram-positive, Gram-negative, and yeast strains are investigated.

Carbon-Based Quantum Dots with Solid-State Photoluminescent: Mechanism, Implementation, and Application.

Carbon-based quantum dots (CQDs), including spherical carbon dots and graphene quantum dots, are an emerging class of photoluminescent (PL) materials with unique properties. Great progress has been made in the design and fabrication of high-performance CQDs, however, the challenge of developing solid-state PL CQDs have aroused great interest among researchers. A clear PL mechanism is the basis for the development of high-performance solid-state CQDs for light emission and is also a prerequisite for the realization of multiple practical applications. However, the extremely complex structure of a CQD greatly limits the understanding of the solid-state PL mechanism of CQDs. So far, a variety of models have been proposed to explain the PL of solid-state CQDs, but they have not been unified. This review summarizes the current understanding of the solid-state PL of solid-state CQDs from the perspective of energy band theory and electronic transitions. In addition, the common strategies for realizing solid-state PL in CQDs are also summarized. Furthermore, the applications of CQDs in the fields of light-emitting devices, anti-counterfeiting, fingerprint detection, etc., are proposed. Finally, a brief outlook is given, highlighting current problems, and directions for development of solid-state PL of CQDs.

Preliminary studies into fluorescent semiconductor nanorods for the detection of latent fingermarks: Size matters, shape matters

The effect of the shape of semiconductor nanocrystals on their performance for visualising latent fingermarks was investigated for the first time. Highly luminescent CdSe/CdS core/shell nanocrystals in rod and spherical shapes were synthesised in organic solvent and transferred to aqueous solution using ligand exchange. The 3-mercaptopropionic acid coated nanorods and nanospheres were characterised using electron microscopy and UV-visible absorbance and luminescence spectrophotometry. A simple and rapid development of fresh to less than a week-old natural fingermarks from 4 donors (male and female) on non-porous surfaces including glass slides, aluminium foil and germanium disks using both CdSe/CdS core/shell nanorods and spherical dots was achieved, wherein nanorods demonstrated an enhanced development of ridge details in comparison to the spherical dots.

Shape-Controlled HgTe Colloidal Quantum Dots and Reduced Spin-Orbit Splitting in the Tetrahedral Shape.

Spherical and tetrahedral HgTe colloidal quantum dots (CQDs) are synthesized, and their doping is tuned electrochemically. Compared to spherical dots of a similar volume, the tetrahedral CQDs show a decrease in confinement energy as well as a sharper band edge absorption. The intraband spectra of the tetrahedral CQDs also display a smaller splitting from spin-orbit coupling. The shape-controlled synthesis with an improved size distribution and sharper optical features could find applications in optoelectronic devices.

Interband optical Raman gain in a strained oxide quantum dot with Hylleraas co-ordinates

Exciton Raman scattering of a three-level system is observed in a CdO/ZnO quantum dot using the size dependent Smorodinsky–Winternitz potential. Resonance Raman excitation for the fundamental optical transition is concentrated in the present work. The differential cross section of Raman optical intensity associated with the exciton is computed with the incident photon energy and the geometrical confinement effect. Raman differential cross section is found by the third-order harmonic generation. The built-in internal fields are incorporated in the heterostructure. They arise between the interior and outer core/shell materials in the heterostructure which contains the spontaneous polarization and piezoelectric polarization. The Hamiltonian of the exciton is included with the dielectric mismatch effect and the variational approach with Hylleraas co-ordinates are employed to obtain the energy eigen values numerically. The energy dependent effective mass of electron and the size related strain-induced potentials for the conduction and valence bands are incorporated in the Hamiltonian. The nonlinear optical properties are obtained with the density matrix approach. The results show that the Raman intensities are more influenced in the strong confinement region. The resonance peak Raman intensity is observed as 6.84 (arb.units) for a 60 A spherical dot. The Raman gain is optimized by varying the dot size. And, the Raman optical gain as high as 240/cm is achieved for the dot radius, 22 A of CdO/ZnO spherical quantum dot. This can be employed for the potential applications in optical devices.

Nanocomposite Polymer Hydrogels Reinforced by Carbon Dots and Hectorite Clay

Herein, two nanoparticles with different dimensions, spherical carbon dots (C-dots) and sheetlike hectorite clay, were used as physical crosslinkers to fabricate C-dots-clay-poly(N-isopropylacrylamide) nanocomposite hydrogels (coded as C-dots-clay-PNIPAm hydrogels). The mechanical properties, fluorescence features and thermal-responsive properties of the C-dots-clay-PNIPAm hydrogels were evaluated. The experimental results indicate that synergistic effects of C-dots and hectorite clay nanoparticles are able to significantly enhance mechanical properties of the hydrogels. The hydrogels can be stretched up to 1730% with strength as high as 250 kPa when the C-dots concentration is 0.1wt% and the clay concentration is 6wt%. The hydrogels exhibit complete self-healing through autonomic reconstruction of crosslinked network a damaged interface. The hydrogels show favorable thermal-responsive properties with the volume phase transition around 34 °C. In addition, the hydrogels are endowed with fluorescence features that are associated with C-dots in the hydrogels. It can be expected that the as-fabricated C-dots-clay-PNIPAm hydrogels are promising for applications in sensors, biomedical carriers and tissue engineering.

Photocatalytic HA deposition on TiO2 of Ti-0.2Pd surface immersed in simulated body fluid

Effect of photocatalysis on apatite formation on Ti-0.2Pd alloy when the metal is immersed in a physiological solution is investigated. The surface of Ti-0.2Pd was treated by a method of thermal oxidation at 400 and 600 °C in air. Immersion tests of Ti-0.2Pd pieces in a simulated body fluid (SBF containing 27 mM HCO3−) at 37 °C for 14 days under ultraviolet (UV) irradiation and in dark environment were carried out. Glancing angle X-ray diffraction and Fourier transform infrared spectroscopy were used to examine the crystallinity and composition of the deposition. Two different morphologies of carbonated hydroxyapatite (HA) deposition: spherical flower shape and dot shape are found formed on the samples. Spherical flower-shaped HA has higher crystallinity and higher Ca/P ratios (1.2–1.4) which are related to the effect of photocatalysis. Dot shaped HA with lower crystallinity and lower Ca/P ratio (0.8–1.0) is found formed on most dark immersed pieces. This work suggests the UV irradiation causes the change of the morphology and crystallinity of HA but has no effect on the quantity of HA formed on Ti-0.2Pd. The chemical composition of the deposition produced on Ti-0.2Pd under UV lighting is closer to that of a crystallized HA compared to that formed in dark.

Fluorescent detection of aspartate transaminase using N-doped carbon dots

The evident spike in the mortality caused due to liver disorders such as liver cirrhosis raised an urgent need for rapid and accurate diagnosis of the disease. Recently, fluorescent carbon dots emerged as an excellent platform for rapid testing in biomedical research. In this work, carbon dots were synthesized by the facile one-step microwave-assisted process by using starch and 50X TAE buffer as the precursors. The synthesized novel nitrogen-doped carbon dots (NCD) exhibited bright blue color fluorescence under the UV lamp. The photoluminescence emission intensity peak was found to be maximum at 440 nm under an excitation wavelength of 350 nm (λex/λem ∼ 350/440 nm). The quantum yield of NCD was calculated as 53%. The microscopic analysis of NCD showed a uniformly spherical carbon dots with an average hydrodynamic diameter measured as 2.8 ± 0.8 nm. The synthesized NCD has been deployed for the detection of oxaloacetate as a biomarker for estimating the level of aspartate transaminase directly or indirectly in liver disorder. The PL emission response of NCD enhances as the concentration of oxaloacetate increases. The role of interfering agents such as Bilirubin (BR), Uric acid (UA), Ascorbic acid (AA), Glucose (Glu), and many more were tested against a similar concentration of oxaloacetate biomarker. The study revealed the higher selectivity of NCD towards oxaloacetate in the presence of several interfering molecules.

Photocatalytic degradation of methyl orange using Carbon Quantum Dots (CQDs) derived from watermelon rinds

In this study, a facile synthesis of carbon quantum dots (CQDs) was successfully conducted by hydrothermal treatment at mild temperature (120 °C) using watermelon rinds as carbon precursor. The synthesized CQDs was aimed to harvest the visible light from artificial source for photocatalytic degradation of methyl orange (MO) dye. The prepared CQDs were characterized by TEM to check the physical properties. The produced CQDs demonstrated a band of spherical dots which display a complete dispersion of particles in water. The spherical morphology of the CQDs was clearly seen with narrow size distribution, averagely around 1 -5 nm in diameter. The CQDs exhibited an excellent photocatalytic performance with 68.9% of MO degradation rate within 120 min reaction owing to the large surface area for adsorption and reaction process to take place.