Photodegradation Of Methylene Blue Research Articles

Multifaceted Applications of DNA-Capped Silver Nanoparticles in Photonics, Photocatalysis, Antibacterial Activity, Cytotoxicity, and Bioimaging.

Deoxyribonucleic acid (DNA) capped silver nanoparticles are exceptional nanomaterials, featuring precise size and shape control enabled by DNA as a capping agent. DNA stabilizes these nanoparticles' role leading to uniform structures for diverse applications. These nanoparticles are excellent in photonics and medical applications, enhancing fluorescence and medical imaging. In this study, we explore the multifaceted applications of DNA-capped silver nanoparticles, delving into their optical, photocatalytic, antibacterial, cytotoxic, and bioimaging properties. Employing UV-visible absorption spectroscopy and scanning electron microscopy, we provide an analysis of confirmation of silver nanoparticles. The investigation demonstrates substantial photocatalytic efficacy, photodegradation of methylene blue is higher than rhodamine 6G. The presence of silver nanoparticles enhances the fluorescence of rhodamine 6G doped sol-gel glasses. Furthermore, our findings illustrate significant antibacterial effects, encompassing both Gram-positive and Gram-negative bacteria, with DNA-capped silver nanoparticles exhibiting antibacterial activity. Cytotoxicity assessments on HeLa cells reveal concentration-dependent effects, with an LC50 value of 47 µL. Additionally, thein vitro experiments with HeLa cells suggest the promising utility of DNA-capped silver nanoparticles for bioimaging applications. This comprehensive analysis highlights the multifunctionality and potential of DNA-capped silver nanoparticles, offering promising avenues for further exploration and innovation within various scientific domains, particularly in the realm of nanomaterial research.

Photocatalytic Degradation of Methylene Blue Dye by Promising Zinc Copper Ferrite Nanoparticles for Wastewater Treatment

In this work, crystalline copper-zinc ferrite nanoparticles were synthesized by a simple co-precipitation method. Morphological characterization of produced samples was done using a scanning electron microscope (SEM). A transmission electron microscope (TEM) was utilised for further identification and confirmation of the particle morphology and size. Moreover, Fourier transformation infrared (FTIR) spectroscopy and X-ray diffraction (XRD) was employed to examine crystalline structure, chemical structure, and surface area respectively. Optical properties were examined by UV–Vis spectroscopy. The results indicate that the Zn0.5Cu0.5Fe2O4 nanoparticles’ crystallite size was 28.5 nm. The experiments focused on the impact of various factors, such as pH levels, initial MB concentration, and nanocatalyst dosage, on the observed photocatalytic efficiency. The photocatalytic performance of Zn0.5Cu0.5Fe2O4 nanoparticles under UV light was evaluated by decolorization of Methylene Blue (MB) azo dye. Photocatalysis degradation of 10 ppm of MB adding 15 mg of Zn0.5Cu0.5Fe2O4 nanoparticles was 94% after 135 min at room temperature and pH value of 9. Further interpretation was carried out and a proposed mechanism for the MB photodegradation by Zn0.5Cu0.5Fe2O4 nanoparticles was suggested.

Evaluation of kinetic constants uncertainty for the metrologically sound comparison of photodegradation efficiency using TiO2 catalysts

The comparison of the efficiency of a pair of catalysts for the photodegradation of a compound in the same irradiation conditions is affected by many independent and correlated random and systematic effects. These comparisons become objective and indisputable if the efficiency difference is estimated with uncertainty, producing an interval encompassing the “true” difference value with a known probability. This work presents a tool for the detailed evaluation of the uncertainty of estimated kinetic constant values and differences by the Monte Carlo Method simulation of all relevant uncertainty components. First-order kinetics were quantified from regression of the concentrations of studied compounds over various degradation times. The efficiency of methylene blue (MB) and sulfamethazine (SMZ) photodegradation using various solid-state catalysts was quantified and compared. Synthesised TiO2 nanoparticles are more efficient than the purchased TiO2 for MB degradation. For SMZ degradation, ruthenium-doped titanate nanowires and ruthenium-doped titanate nanotubes are equally efficient and more efficient than pristine titanate nanowires. The efficiency equivalence can be challenged by quantifying larger and/or less uncertain SMZ concentrations. First-order kinetics was tested by taking the simulated confidence limits of the intercept of the linear regression used to describe this kinetic order. Kinetic constants with asymmetric distribution and a relative expanded uncertainty for a 95 % confidence level between 3.6% and 17% were quantified. Three successively more uncertain procedures for preparing calibrators for the quantification of MB by UV/Vis spectroscopy were tested, concluding that since the same calibration curve is used to quantify all MB solutions, kinetic quantification is not proportionally or significantly affected by this uncertainty component.

A novel synthesis from instability difference between SiC 3-C and 6-H crystal to form nanoparticles stems by alkali solution and its degrading various environmental pollutants

In this paper, the nano silicon carbide with different sizes was prepared without hydrofluoric acid by using simple milling and related low temperature etching process in normal pressure. Also, it was the first time verified that 3-C dominated crystalline form of polycrystalline silicon carbide is etched, leaving the 6-H silicon carbide crystalline form by the Raman spectra and HAADF-STEM (high-angle-annular dark-field scanning transmission electron microscopy) imaging that. The application of the alkali etching technique could precise control the partial structural transformation of silicon carbide crystals to a certain extent, which further expands the traditional crystal structure transformation process. In addition, this paper demonstrates the silicon carbide composites in photocatalytic removal of various organic pollutants from aqueous solutions. In the photo degradation of MB (Methylene Blue), the removal rate of the modified silicon carbide shown ten times as much as the commercial silicon carbide. The 1-h degradation efficiency was significantly higher in the 50 μL H2O2 system (100.0%, 86.8% and 89.9% removal of MB, Rhodamine B, Methyl Orange and Tetracycline hydrochloride, respectively). Furthermore, the unit spin concentrations of vacancy defects, superoxide radicals and hydroxyl radicals were quantitatively analyzed. The vacancy defects of the etched material were 1000 times higher than before, and the modified silicon carbide had higher transmittance to infrared and visible light. It strongly absorbs ultraviolet light. Conversely, the research on micron-sized silicon carbide loaded with Ag and Pt atoms found that it had a nitrogen fixation effect during the warming up process, in a nitrogen atmosphere.

High removal of methyl blue over copper mixed-triazolate MOF by both adsorption and photodegradation from aqueous solution

Copper mixed-triazolate MOFs (CuMtz-3a and CuMtz-3b) containing mixed-ligands (3,5-diphenyl-1H-1,2,4-triazole and 1H-1,2,4-triazole) were prepared and showed enhanced adsorption property towards the adsorption of methyl blue (MB) in comparison with the mono-ligand MOF (CuTz-1). The adsorption capacity (152 mg g−1) of CuMtz-3b is 182% that of the parent MOF CuTz-1. Moreover, CuMtz-3b demonstrated remarkable photocatalytic rate constant (0.031 min−1) in comparison with other reported MOFs and inorganic materials on the degradation of MB. The improvement on the photocatalytic property can be attributed to the higher light absorption ability as well as the separation of charge carriers. Mechanism study shows that the ·O2− radical plays a key role in the reaction. More importantly, the high degradation efficiency of MB over CuMtz-3b can be maintained while preserving the crystallinity and morphology of the catalyst after four cycles of processes, indicating that CuMtz-3b is a reusable and stable material towards the photodegradation of MB.

Green synthesis of tellurium-doped SnO2 nanoparticles with sulfurized g-C3 N4 : Insights into methylene blue photodegradation and antibacterial capability.

The construction of SnO2 nanoparticles (NPs), specifically Te-doped SnO2 NPs, using a simple and economical co-precipitation technique has been thoroughly described in this work. NH3 served as the reducing agent in this procedure, whilst polyethylene glycol served as the capping agent. The primary goals of our work were to investigate the physicochemical properties of the synthesized SnO2 NPs and assess their potential use as antibacterial agents and photocatalysts. Scanning electron microscopy-energy dispersive X-ray, ultraviolet light, Fourier transform infrared spectroscopy, X-ray diffraction (XRD), and other analytical techniques were used to thoroughly analyze the NPs. Based on the full width at half maximum of the most noticeable peaks in the XRD spectrum, the Debye-Scherrer equation was used to calculate the crystallite sizes, which indicated the presence of a single tetragonal SnO2 phase. Particularly noteworthy was the exceptional photocatalytic activity of graphene-assisted Te-doped SnO2 NPs, achieving an impressive decomposition efficiency of up to 98% in the photo-oxidation of methylene blue. Furthermore, our investigation delved into the antibacterial attributes of the synthesized SnO2 NPs against Escherichia coli and Staphylococcus aureus, demonstrating inhibitory effects on both bacteria strains. This suggests potential applications for these NPs in various environmental and medical contexts.

Study of the photocatalytic activity of clay supported TiO2 nanoparticles for methylene blue degradation.

The photocatalytic degradation of a methylene blue (MB) solution was studied using a formulation of TiO2 nanoparticles (NPs) suspended in a commercial antibacterial paint, and supported on clay strips. All experiments were carried out in a batch reactor containing a UV-C light source and the MB solution under stirring. Parameters such as catalyst mass loading, MB concentration, as well as catalyst properties were considered for the experimental procedure. The effect of the mass loading on the photocatalytic activity of the TiO2 formulations immobilized on the clay supports was evaluated using 100, 200, and 500 mg of TiO2 on 40 mL of paint, sampling the MB solution under degradation at 0, 2, 5, 10, 20, 50, 100 and 200 min. The aliquots were analyzed by optical spectroscopy in the 400-1000 range to determine the absorbance, calculate the concentration with the Beer-Lambert equation, and obtain the amount of MB degradation. The maximum photocatalytic degradation of MB for the supported photocatalyst was 52%, 55%, and 60%, respectively. For comparison, suspended TiO2 nanoparticles lead to ca. 95% of MB photodegradation in ca. 60 min. The supported photocatalysts were tested in three consecutive cycles of 200 min to study the mechanical and photocatalytic stability. The activity of the photocatalysts with mass loading of 100 and 200 mg TiO2 decreased to ca. 35% after the three cycles, while the formulation with 500 mg TiO2 remained stable for three cycles. The final samples of each cycle were characterized by XRF, discarding erosion of the material from the support.

Biopolymer Gellan-Gum-Based TiO2: A Green Alternative Photocatalyst Approach for Removal of Pollutants

Titanium dioxide TiO2/gellan gum (GG) in different compositions (1, 3, and 5% GG) was investigated to degrade methylene blue (MB) under UV light. XRD, SEM, and EDS confirmed the anatase phase. The textural properties demonstrated the formation of mesopores. The band gaps were 3.2 eV, 3.0 eV, and 2.9 eV. A photodegradation of MB of 95% was observed using the lowest gum concentration. It was attributed to the photogenerated radicals and the specific surface area. The FTIR spectra showed the photostability of the catalyst after successive cycles. The toxicity tests demonstrated no toxicity after dye degradation. Therefore, TiO2/GG is promising for the treatment of water.

Photocatalytic Epoxy Paint Based on TiO2 for the Decontamination of Water under Visible LED and Sunlight Irradiation

AbstractSemiconductor oxides such as titanium dioxide (TiO2) have been used as photocatalysts for removing contaminants. In addition, TiO2 nanoparticles in suspension form are difficult to recover and recycle, and they are expensive. In our work, titanium dioxide has been immobilized on a commercially available, thermally stable, chemically stable, and cheap polymer. The nanocomposite is synthesized with varying percentages of TiO2, 0.25, 0.5, and 1 weight percent. The obtained nanocomposites were characterized, and the effect of the process parameter (i. e., initial concentration of MB, amount of catalyst, light wavelength, and power of light) was investigated. Also, the results show good photodegradation of MB by the TiO2‐epoxy nanocomposite. The decomposition of 10 ppm methylene blue (MB) during 200 min under 25 W visible LED irradiation can reach 95 %. This value is higher than that obtained with pristine TiO2, which does not have photocatalytic activity under LED light. The antibacterial activity of nanocomposites concerning Escherichia coli and Stephalocous aureus was studied, and an inhibition zone of 2 cm and 3.5 cm was obtained, respectively. Therefore, the TiO2‐epoxy nanocomposite was applied to a glass jar and tested after four months for the degradation of methylene blue (5 ppm) and methyl orange (8 ppm) under sunlight. The paint demonstrated good photocatalytic efficiency of 41 % and 72 % within 310 min, respectively.

Effect of the photonic band gap position on the photocatalytic activity of anodic titanium oxide photonic crystal

The slowing down of the group velocity of light at the edges of the photonic band gap is one of the important optical effects observed in photonic crystals. In particular, the “slow light” effect is used in photocatalysis to increase the photocatalytic activity of semiconductors. In this work, anatase photonic crystals with different spectral positions of the photonic band gap (390–1283 nm, measured in water) were obtained. It is shown that if one of the photonic band gaps is located near the absorption edge of the semiconductor (410 nm), photonic crystal exhibits high photocatalytic activity in the photodegradation of methylene blue. At the same time, the photocatalytic activity of anatase photonic crystal increases by 30% when the photonic band gap of the third order rather than the first order is located near the absorption edge of the semiconductor.

Efficient methylene blue dye removal using hybrid ZnO/Co/Cs photocatalyst beads

This study highlighted the developments of the hybrid photocatalytic system for wastewater treatment in the textile industry. Chitosan (Cs) and cobalt (Co) were introduced into the conventional catalyst zinc oxide (ZnO) to form the hybrid photocatalyst beads. Four different weight ratios of ZnO/Cs (1:1) and ZnO/Co/Cs (1:1:1, 1:2:1 and 2:1:1) beads were synthesized by the sol-gel method. The photocatalytic degradation properties of the hybrid ZnO/Co/Cs were investigated under visible light irradiation for methylene blue (MB) photodegradation. The study focused on the effect of ZnO/Co/Cs composition ratio, irradiation time and the amount of catalyst loading in the photoreactor for five hours of exposure time. The result was that the 1:1:1 ZnO/Co/Cs photocatalyst beads had the highest degradation rate compared to the other systems. Adding Co to the ZnO/Cs photocatalyst improved the photocatalytic activity by increasing the decolourization percentage of methylene blue

A comparative study about the influence of nitrogen doping and oxygen vacancies on the photocatalytic performance of ceria

Aimed to evaluate the influence of nitrogen doping on the photocatalytic performance of ceria, three ceria samples, including nitrogen doped, rich oxygen vacancies contained and contrastive ceria were prepared from the decomposition of CeCO3OH under varied atmospheres. The physico-chemical characterizations and photocatalytic properties towards methylene blue (MB) and tetracycline (TC) of the obtained ceria were comparatively discussed in detail. Nitrogen-doped CeO2 exhibited significantly superior photocatalytic activities compared to CeO2 with rich oxygen vacancies for MB and TC photodegradation, which is mainly attributed to the significantly enhanced separation of photo-generated carriers (e−/h+). Density Functional Theory (DFT) simulation suggests that the introduced impurity states of N-doped CeO2 advance the formation and separation of e−/h+. Moreover, the electrons are simultaneously excited from N 2p and O 2p, which further elevates the carrier concentration on the nitrogen-doped CeO2, and promotes the effect of e− during the photodegradation. The obtained results offer powerful evidences for the significant enhancement on photocatalytic performances of nitrogen doped CeO2.

Photocatalytic activity enhancement of g-C3N4 nanosheets through simultaneous inter- and intra-layer charge separation using a facile mechano-thermal method

Herein, a novel mechano-thermal approach has been proposed to tune the electronic structure and enhance the photocatalytic performance of g-C3N4 nanosheets. According to the results, the high-energy ball-milling method modified the role of the ammonium chloride from the blowing agent to the doping agent, leading to the introduction of the interstitial and substitutional Chlorine (Cl) atoms into the nanosheet structure. Such a modification not only promoted electron-hole separation through the inter- and intra-layer of the g-C3N4 nanosheets, but it also led to the band gap energy reduction and higher oxidation capability of the photogenerated holes. These key improvements have been reflected in the optimized sample with a high-energy ball-milling time of 15 min (g-C3N4–15). Compared to the sample without the ball-milling process, g-C3N4–15 exhibited simultaneous intra- and inter-layer charge separation, reduction in the band gap energy from 2.82 to 2.76 eV, and positive shift in the valence band. Furthermore, these modifications in the electronic structure of the nanosheets contributed to the outstanding photocatalytic performance of the g-C3N4–15 towards methylene blue (MB) photodegradation. Among the samples with different ball-milling times, g-C3N4–15 demonstrated the highest MB photodegradation rate constant (0.0125 min−1), approximately 9 times greater than the sample without the ball-milling process. Additionally, the proposed photodegradation pathway suggested that the positive shift in the valence band of g-C3N4–15 could activate hydroxyl radicals (.OH) and promote demethylation and ring-opening of MB dyes.

Intermixing of MoS2 and WS2 photocatalysts toward methylene blue photodegradation.

Visible-light-driven photocatalysis using layered materials has garnered increasing attention regarding the degradation of organic dyes. Herein, transition-metal dichalcogenides MoS2 and WS2 prepared by chemical vapor deposition as well as their intermixing are evaluated for photodegradation (PD) of methylene blue under solar simulator irradiation. Our findings revealed that WS2 exhibited the highest PD efficiency of 67.6% and achieved an impressive PD rate constant of 6.1 × 10-3 min-1. Conversely, MoS2 displayed a somewhat lower PD performance of 43.5% but demonstrated remarkable stability. The intriguing result of this study relies on the synergetic effect observed when both MoS2 and WS2 are combined in a ratio of 20% of MoS2 and 80% of WS2. This precise blend resulted in an optimized PD efficiency and exceptional stability reaching 97% upon several cycles. This finding underscores the advantageous outcomes of intermixing WS2 and MoS2, shedding light on the development of an efficient and enduring photocatalyst for visible-light-driven photodegradation of methylene blue.

Photocatalytic evaluation of chitosan and its derivative coated vanadium pentoxide nanoparticles for photodegradation of methylene blue

Vanadium pentoxide (V2O5) is widely utilized as a photocatalyst for the degradation of various pollutants due to its narrow bandgap and convertible oxidation states of vanadium. Here, V2O5 nano-adsorbents coated with functionalized chitosan exhibit a great sensitivity to the absorption of visible light that makes them a suitable candidate to study the photodegradation of methylene blue in the natural atmosphere. Characterization results revealed the synthesis of chitosan-anisaldehyde Schiff base and its presence over the surface of nanoparticles. Fabricated nanoparticles exhibited enhanced optical band gap that increases the photodegradation efficiency by reducing the recombination rate as well as they possess an orthorhombic crystalline phase as confirmed by XRD. Among all fabricated nanoparticles, one of the coated nano-adsorbents, chitosan-anisaldehyde adorned V2O5 (CHA1), having wedge-shaped pores that aided in the photocatalytic destruction of methylene blue illustrates the best degradation efficiency as compared to the bare ones.

Microwave-assisted synthesis of ZnO structures for effective degradation of methylene blue dye under solar light illumination.

The presence of dyes in wastewater poses a high risk to both human health and the environment due to their potential toxicity and ecological impacts. Zinc(ii) oxide is a low-cost, non-toxic material that can serve as a sustainable and effective solution to the global water pollution crisis. In this study, we propose a facile one-step synthesis of various ZnO structures by microwave irradiation. The primary goal of this study was to explore the morphology-dependent photocatalytic activity of various ZnO structures, as well as the impact of interfering anions on the Methylene Blue (MB) photodegradation under solar light illumination. Photocatalytic activity studies show that the sample denoted as 0.56 M-ZnO with a sheet-like structure has remarkable catalytic activity under solar light illumination, reaching ∼96.6% degradation of 30 mL MB solution (3 × 10-5 M) within 40 minutes. The BET specific surface area and band gap of the optimal 0.56 M-ZnO sample were observed to be 12.42 m2 g-1 and 2.89 eV, respectively. It was shown that the presence of anions like Cl-, NO3-, and HCO3- can reduce the catalytic activity of 0.56 M-ZnO structure to some extent, although more than 70% MB degradation can still be obtained under neutral pH conditions. The superior catalytic efficacy observed in the 0.56 M-ZnO photocatalyst can be attributed to its improved crystallinity, large surface area, and enhanced production of hydroxyl radicals. The low-cost synthesis, combined with high photocatalytic activity collectively underscores the efficiency and practical usability of produced ZnO photocatalysts for dye degradation.

Synthesis and performance evaluation of zinc oxide tubes/alginate microfibre composites for photodegradation of methylene blue: a novel reporting approach.

This research investigates the efficacy of zinc oxide (ZnO) tubes in decontaminating polluted water using a substrate-free hydrothermal synthesis process for ZnO tubes. The synthesized tubes are impregnated into calcium alginate microfibres, strategically chosen for their high surface area to enhance photocatalytic degradation performance and for practical handling during decontamination and subsequent collection, thereby preventing secondary contamination. Structural and morphological analyses, conducted using Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD), thoroughly characterize the properties of the ZnO tubes and the composite material. The efficacy of this composite is demonstrated through the photocatalytic degradation of methylene blue (MB), as a representative organic pollutant, resulting in an 88% degradation of MB after 5 hours of irradiation by a sun simulator. Cyclic tests exhibit consistent degradation levels in the first four cycles (81-89%), followed by a subsequent decrease to 72% in the fifth cycle, coinciding with the breakdown of the microfibres into shorter fragments. Innovatively, this study introduces an approach to reporting photocatalytic degradation results, utilizing normalized pollutant concentration plotted against irradiated energy instead of time, as energy encompasses irradiated power, time, and surface area. This reveals that the 88% degradation of MB is achieved by irradiating the sample with an approximately 18 kJ. Additionally, a new metric, Specific Energy Efficiency (SEE), is introduced. It expresses the ratio of degraded pollutant mass to the mass of photocatalytic active material per unit of irradiated energy, with the maximum and cumulative SEE in this study being 1.044 μg g-1 J-1 and 326 ng g-1 J-1, respectively. This research not only contributes to the understanding of ZnO tubes' efficiency in polluted water decontamination but also introduces valuable insights for standardized reporting in photocatalytic degradation studies.

The influence of the coprecipitation synthesis methods on photodegradation efficiency of ZnFe based photocatalysts

Organic dye pollutants that are progressively used in modern chemical industries, emerged as a major source of water contamination. A promising eco-friendly and simple approach to water purification is the heterogeneous photocatalytic process that uses various metal oxide semiconductors in the presence of light, initiating the oxidation-reduction reactions resulting in dye degradation. The aim of this study was to investigate the influence of coprecipitation synthesis methods on photodegradation efficiency. The ZnFe based photocatalysts were synthesized using two different methods: low (LS) supersaturation and high (HS) supersaturation coprecipitation and thermally activated at 100, 300, 500 and 700?C. Structural and textural characterisation were carried out and their efficiency in methylene blue photodegradation test reaction was studied. LS samples treated at 100 and 300?C exhibited very low photodegradation efficiency (less than 10 %) when compared to HS samples treated at the same temperatures (75 and 85 %). The efficiency of LS 500 and LS 700 samples improved (67 and 75 %) with the increase in thermal treatment temperature and the photodegradation efficiency difference between LS and HS samples decreased. Such behaviour of LS and HS samples could be explained by structural and textural properties that originated from different synthesis methods.

Ternary nanohybrid of biochar/ NiFe2O4 /Ag3PO4 for simultaneous adsorption of Hg(ІІ) and photodegradation of methylene blue; modeling, kinetic and isotherm studies

In this research, a ternary composite of biochar - nickel ferrite – silver phosphate has been characterized and employed for methylene blue photodegradation and mercury adsorption. Response surface methodology was adopted to optimize effective parameters on removal. It was found that maximum dye degradation and mercury adsorption was obtained at pH of 7 with dosage of 26 mg and 90 min reaction time. Moreover, the composite of biochar/NiFe2O4/Ag3PO4 with the ratio of 70:20:10 able to remove 94 % of dye and 98.5 % of mercury at the initial concentration of 10 mg L−1. It was found that the rate of methylene blue degradation increase with increasing the temperature as it was destroyed at a temperature of 45 °C within 1 h. Kinetic and isotherm studies for the adsorption experiments showed that mercury adsorption followed the pseudo – second order kinetic model and Langmuir adsorption isotherm. Moreover, thermodynamic study indicated that the adsorption process is spontaneous with an endothermic path. With a good maximum adsorption capacity of 241 mg g−1 and four cycle reusability, the prepared composite is a suitable candidate to simultaneously mitigate the side effect of dye and heavy metal in aqueous media.

Simultaneous preparation of ZnO/rGO composites through Zn(OH)2 decomposition and graphite oxide reduction and their photocatalytic properties.

ZnO/reduced graphite oxide (rGO) composites were simultaneously prepared by the thermal reduction of graphite oxide (GO) and the decomposition of Zn(OH)2. The samples were characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, photoluminescence, and DRS. Results indicate that Zn(OH)2 was heated and decomposed into ZnO at a low temperature (200 ℃), while GO was reduced to graphene. The synthesized ZnO particles were small and loaded on graphene layers. The ZnO/rGO photocatalysts exhibited excellent photocatalytic activity against methylene blue (MB) under simulated sunlight irradiation. The ZnO/50% rGO photocatalyst showed the best MB photodegradation rate of up to 99.7% within 3min. Synchronous reaction provided an efficient, simple, and fast preparation method for ZnO/rGO composites, with an excellent solar photocatalytic degradation ability.