Band Gap Energy Of ZnO Research Articles

ZnO quantum dot based thin films as promising electron transport layer: Influence of surface-to-volume ratio on the photoelectric properties

ZnO quantum dots (QDs) with average particle size of 4.4 nm were prepared using a low temperature processing solvothermal route. ZnO QD based thin films were then prepared from the ZnO QD based solution using spin coating technique and annealed at 250, 350 and 450 °C. The average grain size and energy band gap of ZnO were respectively increased and decreased from 5.5 to 22.9 nm and 3.37 to 3.27 eV upon increasing the annealing temperature up to 450 °C. The photoluminescence analysis showed that the as-coated ZnO film and ZnO film annealed at 250 °C have high density of oxygen vacancies; these defects were reduced upon increasing the temperature to 350 and 450 °C. The photoelectric properties of the films were strongly affected by the grain size and the defects present in the films. The photo-to-dark current ratio (PDCR) was decreased from 3723 to 371%, whereas the responsivity was increased from 1.25 to 218 mA/W with the increase of temperature to 450 °C. As-coated and 250 °C-annealed films exhibited better photoresponse than others in terms of PDCR, rise time and fall time due to their larger surface-to-volume ratio, making them promising candidate as electron transport layer in perovskite solar cells.

Fabrication of Cr–ZnO photocatalyst by starch-assisted sol–gel method for photodegradation of congo red under visible light

In this work, a sol–gel method has been employed to fabricate Cr-doped ZnO nanoparticles (NPs) in the presence of starch at different annealing temperatures. The obtained products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS), and Fourier transforms infrared spectroscopy (FTIR). All samples were defined as hexagonal wurtzite ZnO with particle sizes equal to 26, 22, and 31 nm for pure ZnO, Cr-doped ZnO at 500 °C and 700 °C, respectively. The Cr-doped ZnO photocatalyst at 500 °C shifted the band gap energy of ZnO from 3.16 to 3.09 eV. The nanomaterials' photocatalytic activity was tested through the photodegradation of congo red (CR) under visible light illumination. The results demonstrated that the Cr-doped ZnO annealed at 500 °C is an excellent photocatalyst with enhanced degradation competence towards CR dye by virtue of its reduced size and lower band gap energy. The kinetics of the photodegradation fitted the pseudo-first-order model while the mechanistic investigations revealed the great impact of h+ and ·OH on the degradation process. The starch-stabilized chromium-doped ZnO shows a high photocatalytic activity towards CR, indicating their possible environmental remediation application.

Surface engineering of diatomite using nanostructured Zn compounds for adsorption and sunlight photocatalysis

Diatomite, composed of amorphous macroporous hydrated silica, has generated increasing attention as an attractive raw material for elimination of heavy metal, while suffering low surface activity. Herein, easily separable diatomite adsorbents modified by Zn compounds are developed for effective adsorption of Pb(II), Cu(II) and Cd(II) ions and sunlight photoreduction of toxic Cr(VI) to low-toxic Cr(III). The micro-structure and functionality are characterized through energy spectrum and spectroscopic analysis. Sulfion S2− or carbonyl COO− interlinked networks on the modified diatomite are effective for capturing Pb(II), Cu(II) and Cd(II) ions, and are capable of being oxidized to generate diatomite@ZnO directly at 450 °C in air atmosphere. Significantly, by recycling the used diatomite@ZnS (Dt@ZnS) adsorbents loaded by Cu(II) and Cd(II) ions, Cu or Cd doped ZnO photocatalysts can be fabricated on diatomite to vary band gap energy of ZnO for more efficient absorption of visible light for Cr(VI) photoreduction under sunlight irradiation. Although the derivatives exhibit weakened Cr(VI) photoreduction capacity compared with Dt@ZnS precursor, probably owing to the influence of surface deposits of Cu(II) or Cd(II) on doping efficiency and light absorption, this idea offers a promising solution to convert the used adsorbents loaded by poisonous heavy metals into photocatalysts for secondary utilization in waste water purification, thus making it possible to produce tailor-made materials for specific requirements alternative by the reutilization of discarded heavy metal adsorbents.

New Electrospun ZnO:MoO3 Nanostructures: Preparation, Characterization and Photocatalytic Performance.

New molybdenum trioxide-incorporated ZnO materials were prepared through the electrospinning method and then calcination at 500 °C, for 2 h. The obtained electrospun ZnO:MoO3 hybrid materials were characterized by X-ray diffraction, scanning and transmission electron microscopies, ultraviolet (UV)-diffuse reflectance, UV–visible (UV–vis) absorption, and photoluminescence techniques. It was observed that the presence of MoO3 as loading material in pure ZnO matrix induces a small blue shift in the absorption band maxima (from 382 to 371 nm) and the emission peaks are shifted to shorter wavelengths, as compared to pure ZnO. Also, a slight decrease in the optical band gap energy of ZnO:MoO3 was registered after MoO3 incorporation. The photocatalytic performance of pure ZnO and ZnO:MoO3 was assessed in the degradation of rhodamine B (RhB) dye with an initial concentration of 5 mg/L, under visible light irradiation. A doubling of the degradation efficiency of the ZnO:MoO3 sample (3.26% of the atomic molar ratio of Mo/Zn) as compared to pure ZnO was obtained. The values of the reaction rate constants were found to be 0.0480 h−1 for ZnO, and 0.1072 h−1 for ZnO:MoO3, respectively.

Assimilation of Yb defect states in ZnO: Structural, optical and magnetic investigations

Magnetic ordering in the non-ferromagnetic substances (like; ZnO) is intriguing and could be more interesting to investigate if other defect states are incorporated by the non-magnetic ion doping. We have investigated the effect of Yb doping on the structural, morphology, optical and magnetic properties of ZnO. Different Yb concentrations were applied to prepare the solid solution of Zn1-xYbxO (with x = 0.00, 0.01 and 0.05) using the co-precipitation route. X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), high resolution scanning electron microscope (HR-SEM), UV–visible spectroscopy and vibrating sample magnetometer (VSM) have been employed to characterize the samples. Amalgamation of Yb in ZnO has manifested the lower angle shifting of XRD peaks and consequently increased lattice parameters of ZnO are observed. UV–visible absorption spectroscopy investigations have established the net decrease in the optical band gap energy of ZnO as a function of Yb defect levels in the compound. HR-SEM study revealed that the insertion of Yb ions in ZnO could transform the spherical structures into agglomerated non-spherical structures. The magnetic measurements have revealed the diamagnetic ordering in the pure ZnO, which ultimately transformed into ferromagnetic ordering via incorporation of Yb defect states.

Green synthesis of reduced graphene oxide grafted Ag/ZnO for photocatalytic abatement of methylene blue and antibacterial activities

We have reported a facile, green synthesis of reduced graphene oxide (RGO) grafted Ag/ZnO (RGO-Ag/ZnO) nanocomposite in the presence of L-Methionine (L-Met) for synergetic photocatalytic degradation of methylene blue (MB) and antibacterial activities. L-Met shows an excellent efficiency as stabilizing and reducing agents for the synthesis of both Ag NPs and RGO. The successful synthesis of pure phase L-Met-RGO-Ag/ZnO was confirmed by XRD. According to UV-DRS analysis, the doping of Ag resulted in a decrease bandgap energy of ZnO from 3.34 eV to 3.18 eV. The mixed morphologies of the nanocomposite were studied by SEM and TEM. The photocatalytic degradation efficiency of L-Met-RGO-Ag/ZnO towards MB dye was investigated at varying initial concentrations of MB dye, H2O2, and ultrasonication. The optimum degradation efficiency of the nanocomposite (50 mg) at room temperature (25 °C) was found to be 99% with an initial MB dye concentration of 10 mg/L and 120 min contact time. The fast degradation of MB dye was observed in the presence of H2O2. The ultrasonication of the catalyst vanishes the synergetic interface of the nanocomposite, as a result, poor photocatalytic performance (85%) was observed even at a long period of contact time (210 min). Moreover, RGO-Ag/ZnO nanocomposites have shown strong antibacterial activity against both Gram-positive bacteria (B. Subtilis) and Gram-negative bacteria (E. coli). In conclusion, RGO-Ag/ZnO nanocomposite shows a promising photocatalyst for the degradation of organic dyes and antibacterial activities.

Preparation of ZnO nanoparticles in n-hexane-water system using Moringa oliefera leaf extract and its photodegradation activity

In this study, ZnO nanoparticles were successfully synthesized using Moringa oliefera leaf extract in two phases system of n-hexane-water. The presence of secondary metabolites in n-hexane acts as a weak base source and precursor of Zn(NO3)2, in water were needed for the formation of ZnO nanoparticles. ZnO nanoparticles were further characterized using UV-Vis Diffuse Reflectance Spectroscopy(DRS), Fourier Transform Infrared (FTIR), X-Ray Diffraction (XRD), Scanning Electron Microscopy-Energy Dispersive X-Ray (SEM-EDX), and Tunneling Electron Microscopy (TEM). Based on TEM characterization, the particles size of ZnO nanoparticles was approximately 67 nm. The band gap energy of ZnO was 3.2 eV. The photocatalytic activities of ZnO nanoparticles were observed through the methylene blue (MB) degradation under UV-light irradiation. The percentage of MB degradation was 99 % for 2 h.

Treatment of Methylene Blue Dye Using Immersed Lamp Photocatalytic Reactor: 5 L Scale Study

The present investigation studied methylene blue dye treatment using 5-L immersed lamp photocatalytic (UV) reactor. Dye treatment further studied using catalysts effects such as H2O2, ZnO, and TiO2. The marginal higher degradation was obtained for ZnO/UV compared to TiO2/UV effect, and it may be due to higher bandgap energy of ZnO. The maximum degradation was obtained for H2O2/UV (2 g/L) effect. The optimum findings of the present work were initial dye concentration: 31.3 µM, pH: 11, operating temperature: 28 °C, moles of dye removed: 30.1 ± 1.6 µM, moles of total organic carbon removed: 350.4 ± 17.5 µM, rate constant (pseudo-first order): 18.3 ± 0.7 × 10−3 min−1, and energy: 9.4 ± 0.4 × 10−3 µM. The present work showed the higher potential of scale-up photocatalytic reactor for treatment dye pollutants.

Fabrication of spray derived nanostructured n-ZnO/p-Si heterojunction diode and investigation of its response to dark and light

Abstract Fluorine doped ZnO thin films were grown by chemical spray pyrolysis technique of zinc acetate and ammonium fluoride, and the effect of fluorine content on structural, optical and electrical properties were evaluated. The structural, morphological, optical properties of ZnO films were investigated by XRD (X-ray diffraction), AFM (Atomic force microscopy), SEM (Scanning electron microscop) and UV–Vis spectroscopy, respectively. According to results, it was observed that all films had polycrystalline texture with hexagonal wurtzite crystal structure and film surface were made up of nano-scale grains, varied by fluorine content. Optical properties showed that optical band gap energy of ZnO changed from 3.28 to 3.24 eV with F content. Shrinkage effect was assessed as the cause in the variation of optical band gap values. Finally, current-voltage (I-V) analysis was performed in Au/ZnO:F/p-Si device in dark and light conditions and certain diode parameters such as ideality factor, barrier height and series resistance were calculated and discussed in detail.

STUDIES ON STRUCTURAL, SURFACE MORPHOLOGICAL, OPTICAL, LUMINESCENCE AND UV PHOTODETECTION PROPERTIES OF SOL–GEL Mg-DOPED ZnO THIN FILMS

Undoped and magnesium-doped zinc oxide thin films were prepared by the sol–gel method. Results from X-ray diffraction indicated that the films exhibited a hexagonal wurtzite structure and were highly oriented along the [Formula: see text]-axis. The intensity of the (002) diffraction peak increased with increasing the Mg doping concentration. Also, Mg doping inhibited the growth of crystallite size which decreased from 46[Formula: see text]nm to 38[Formula: see text]nm with doping concentration. Morphological studies by atomic force microscopy (AFM) indicated the uniform thin film growth and the decreasing of grain size and surface roughness with Mg doping. Optical analysis showed that the average transmittance of all films was above 90% in the visible range and Mg doping has significantly enhanced the bandgap energy of ZnO. Two Raman modes assigned to [Formula: see text] and [Formula: see text] for the ZnO wurtzite structure were observed for all films. UV emission peak and three defect emission peaks in the visible region were observed by photoluminescence measurements at room temperature. The intensity ratio of UV emission to the visible emission increased with the Mg concentration. Photocurrent measurements revealed that all films presented the photoresponses with [Formula: see text]-type semiconducting behavior and their generated photocurrents were reduced by Mg doping. The prepared thin films of high quality with improved properties by Mg doping could be proposed to workers in the field of optoelectronic devices for using them as a strong candidate.

Enhanced ultraviolet emission from self-assembled ZnO nanorods grown on graphene

We report the intense room temperature ultraviolet photoluminescence (PL) emission from self-assembled vertically aligned ZnO nanorods grown directly on graphene. The PL intensities from ZnO nanorods grown on other van der Waal bulk solids such as highly oriented pyrolytic graphite and mica under the same experimental condition are also compared. The enhanced PL signal from ZnO nanorods grown on graphene is explained on the basis of lattice matching of ZnO with that of graphene leading to high crystal quality. Furthermore, the role of graphene plasmons on the enhanced PL signal is explored by studying the micro-PL mapping on a single nanorod lying horizontally on the graphene surface. The uniform and high PL intensity distribution is noticed along the central axis of the rod, and the intensity distribution decreases toward either side of the central axis. The occurrence of such intensity distribution is explained by resonant excitation of graphene plasmon near bandgap energy of ZnO, which is modulated by surface corrugation of graphene and followed by its transformation into the propagating photon.

ZnO/CuO nanocomposite prepared in one-pot green synthesis using seed bark extract of Theobroma cacao

A method for green synthesis of ZnO/CuO nanocomposite using Theobroma cacao seed bark extract (TBE) has been investigated. ZnO/CuO nanocomposite synthesis aims to decrease a high band gap energy of ZnO. Zn(NO3)2 and Cu(NO3)2 solutions were used as a precursors. TBE can substitute NaOH as the base source material which contained alkaloids as shown from the phytochemical test. Identification of nanocomposite was characterized by UV–Vis diffuse reflectance spectrophotometry (DRS), Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX), transmission electron microscopy (TEM), X-ray diffraction analysis (XRD) and Fluorescence Spectrophotometer. ZnO/CuO nanocomposite had the band gap energy of 2.3 eV. TEM result showed the size of ZnO/CuO nanocomposite was 20–50 nm.

Structural, Optical, and Photocatalytic Activities of Ag-Doped and Mn-Doped ZnO Nanoparticles

We report the photocatalytic activities of ZnO, Ag-doped ZnO, and Mn-doped ZnO nanoparticles (NPs). Ag-doped and Mn-doped ZnO samples were synthesized using a coprecipitation method and calcined at 600°C. XRD, SEM, EDX, and UV-vis spectroscopy techniques were employed for characterization of the synthesized samples. The photocatalytic activities of the samples were evaluated by measuring the photocatalytic decolorization of methyl violet with sunlight being the source of energy. XRD patterns of the samples confirmed the wurtzite structure without change which was indicative of the absence of Mn- and Ag-related secondary phases for the doped ZnO. The UV-vis spectra indicated the band gap energy of ZnO, Ag-doped ZnO, and Mn-doped ZnO to be 2.98, 2.80, and 2.64 eV, respectively. Photocatalytic decolorization of methyl violet for the synthesized samples was found to be favorable at a pH of 9.0, catalyst dose of 1 g/L, and initial dye concentration of 4.5 × 10−4 g/L. Mn-doped ZnO and Ag-doped ZnO photocatalytic decolorization efficiency was significantly higher than undoped ZnO. Incorporation of Mn and Ag enhanced the visible-light photocatalytic activity of ZnO; this could be due to the ability of these metals to increase the surface defects of ZnO which in turn shift their optical absorption towards the visible region.

Effects of Mn doping on the structural, linear, and nonlinear optical properties of ZnO nanoparticles

In this study, the synthesis and characterization of undoped and Mn-doped ZnO nanoparticles with 2%, 5%, and 15% Mn/ZnO prepared using the hydrothermal method were reported. The structural, morphological, and chemical-bond properties of the Mn-doped ZnO nanoparticles were studied by using x-ray diffraction, field emission scanning electron microscopy (FESEM), energy dispersive x-ray analysis, and Fourier transform infrared spectroscopy analysis. X-ray diffraction patterns indicate that all of the samples have hexagonal wurtzite structures. The average diameters of the Mn-doped ZnO nanoparticles with different Mn/ZnO ratios were estimated to be about 20–38 nm from the FESEM images. The linear absorption coefficient and optical band gap energy of ZnO and Mn-doped ZnO nanoparticles were calculated using UV-Vis spectroscopy. A decrease in Eg was observed by an increase in Mn concentration. The nonlinear optical measurements have been performed using a nanosecond Nd:YAG pulse laser by the Z-scan technique. Both the undoped and Mn-doped ZnO nanoparticles exhibited a negative nonlinear optical index of refraction at 532 nm relating to the self-defocusing phenomenon. The nonlinear optical absorption of ZnO and Mn-doped ZnO nanoparticles is attributed to two-photon absorption combined with free carrier absorption. Furthermore, the third-order nonlinear susceptibility values of the undoped and Mn-doped ZnO nanoparticles varied between 1.2−2.5×10−9 esu, depending on the Mn contents. The results suggest that a Mn dopant can improve the nonlinear optical properties of ZnO nanoparticles, and Mn-doped ZnO nanoparticles synthesized through the hydrothermal method may be a promising candidate for nonlinear optical applications at 532 nm.

ZnO based transparent thin film transistor grown by aerosol assisted CVD

The communication reports the characterization of n $$^+$$ -Al:ZnO/Al $$_2$$ O $$_3$$ /n-ZnO thin film transistors (TFTs) developed by using an indigenously designed low-cost aerosol assisted chemical vapour deposition (AACVD) system. UV–VIS spectroscopy yields the bandgap energies of ZnO and Al:ZnO thin films as 3.30 and 3.34 eV, respectively. The average optical transmittance of the TFT is found to be around 77%. The TFT has a double top gate structure with Al:ZnO thin film as gate, source and drain terminals, ZnO thin film as channel layer while Al $$_2$$ O $$_3$$ acts as the dielectric layer. Transfer and output characteristics of the TFT have been measured to study the variation of threshold voltage, current On/Off ratio, saturation field effect mobility and subthreshold swing parameters as functions of drain-to-source voltage. The present work establishes the good quality indigenous fabrication of p-channel TFT using AACVD system with results agreeing very well with the results available in the literature.

Flower-like Bi2WO6/ZnO composite with excellent photocatalytic capability under visible light irradiation

The photocatalytic ability of ZnO is improved through the addition of flower-like Bi2WO6 to prepare a Bi2WO6/ZnO composite with visible light activity. The composite is characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy with UV–vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy and N2 adsorption-desorption isotherms. After modification, the band gap energy of Bi2WO6/ZnO is reduced from 3.2 eV for ZnO to 2.6 eV. Under visible light irradiation, the Bi2WO6/ZnO composite shows an excellent photocatalytic activity for degrading methylene blue (MB) and tetracycline. The photo-degradation efficiencies of (0.3:1) Bi2WO6/ZnO for MB and tetracycline are approximately 246 and 4500 times higher than those of bare ZnO, respectively, and correspondingly, the photo-degradation rates for the two pollutants are approximately 120 and 200 times higher than those with bare ZnO, respectively. Moreover, the photocatalyst of (0.3:1) Bi2WO6/ZnO exhibits a higher transient photocurrent density of approximately 4.5 μA compared with those of bare Bi2WO6 and ZnO nanoparticles. The successful recombination of Bi2WO6 and ZnO enhances the photocatalytic activity and reduces the band gap energy of ZnO, which can be attributed to the effective separation of electron–hole pairs. Active species trapping experiments display that [O2]− is the major species involved during photocatalysis rather than •OH and h+. This study provides insight into designing a meaningful visible-light-driven photocatalyst for environmental remediation.

Optical and Structural Characterization of ZnO/TiO2 Bilayer Thin Films Grown by Sol-Gel Spin Coating

Structural and optical properties of ZnO/TiO2 bilayers thin films have been investigated using x-ray diffraction (X-RD), scanning electron microscopy (SEM), and optical transmittance UV-Vis measurements. ZnO thin films were prepared by dissolving zinc acetate dehydrated into a solvent of ethanol and then added triethanolamin. In the case of TiO2 layers, tetraisoproxide was dissolved into ethanol and then added an acetate acid. The layer of ZnO was deposited first followed by TiO2 layer on a glass substrate using a spin coating technique. The ZnO/TiO2 bilayers were annealed at various temperatures from 300°C until 600°C for 60 minutes. The X-ray diffraction results show that there was an enhancement of the x-ray spectra as annealed temperature increased to 600°C in comparison to the samples that were annealed at 300°C. Based on the optical measurement of UV-Vis, the band gap energy of ZnO/TiO2 bilayer is around 3.2 eV at temperature of 300°C. This value is similar to the band gap energy of ZnO. SEM results show that there is no cluster in the surface of ZnO/TiO2 bilayer.

Synthesis of nanostructure manganese doped zinc oxide/polystyrene thin films with excellent stability, transparency and super-hydrophobicity

Superhydrophobic transparent thin films using Mn doped zinc oxide (Mn/ZnO) and polystyrene (PS) composites have been synthesized successfully by chemical solution method. The nanocomposites thin films were fabricated by using Mn/ZnO and PS mixture in toluene, followed by film casting on glass substrate. For a comparison ZnO nanoparticles thin film was also prepared with PS. Mn/ZnO nanostructures have been synthesized by hydrothermal method using hexamethylenetetramine (HMTA) as a capping agent. The XRD analysis shown that the development of hexagonal wurtzite structure of Mn/ZnO with preferred (101) orientation. SEM analysis shown that Mn/ZnO nanorods have been uniformly dispersed in the PS matrix. Water contact angle (WCA) was found as 107° and 151° for the ZnO@PS and Mn doped ZnO@PS thin film, respectively. The transparency of the Mn doped ZnO@PS films are also large (∼90%) as compared to ZnO@PS film (∼80%) which is attributed to enhanced energy band gap of ZnO after Mn doping. The larger contact angle (WCA ∼151°) in the Mn/ZnO@PS thin film has been recognized to the rough surface of PS thin film due to the presence of Mn/ZnO nanorods. The present process is very simple and embrace ability for extensive applications for making super hydrophobic transparent surfaces.

Hydrothermally grown of well-aligned ZnONRs: dependence of alignment ordering upon precursor concentration

The well-aligned Zinc Oxide Nanorods (ZnONRs) arrays was obtained through a hydrothermal process at various precursor concentrations (PC) under a growth temperature of 90 °C for an hour. The effect of PC (0.02, 0.03, 0.04, 0.05, and 0.06 M which is denoted as K0.01–K0.06) to the structural, optical, and morfology (diameter, height, slope, and density) of ZnONRs were studied by using X-ray diffraction, UV–Vis spectroscopy, and field emission scanning electron microscopy (FESEM). As-synthesized ZnONRs exhibit an uniform growth direction along the [002] orientations with average diameters in the range of 40–90 nm. These nanorods showed a strong optical absorption peak centering at 367 nm,which is equivalent to optical energy band gap of ZnO 3.37 eV, confirming the formation of ZnONRs. The morfology of ZnONRs in term of diameter, height, slope, and density increases with the PC. The highest density of approximately 182 number/µm−2 with average slope of 6 degree (aligning percentage of 83 ± 12%) was obtained at the PC of K0.04. It is interesting to find that the dye sensitized solar cell utilizing the sample K0.04 showed five times increasing in the power conversion efficiency as compared to that of device utilizing K0.02 sample.

Carboxymethyl cellulose stabilized ZnO/biochar nanocomposites: Enhanced adsorption and inhibited photocatalytic degradation of methylene blue

Biochar(BC)-supported nanoscaled zinc oxide (nZO) was encapsulated either with (nZORc/BC) or with no (nZOR/BC) sodium carboxymethyl cellulose (CMC). The X-ray diffraction and ultraviolet (UV)-visible-near infrared spectrophotometry revealed that nZO of 16, 10, and 20 nm with energy band gaps of 2.79, 3.68 and 2.62 eV were synthesized for nZOR/BC, nZORc/BC and nZO/BC, respectively. The Langmuir isotherm predicted saturated sorption of methylene blue (MB) was 17.01 g kg−1 for nZORc/BC, over 19 times greater than nZOR/BC and nZO/BC. Under UV irradiation, 10.9, 61.6, 83.1, and 41.6% of MB were degraded for nZORc/BC, nZO/BC, nZOR/BC and BC. The scavenging experiment revealed hydroxyl radical dominated CMC degradation. Exogenous CMC (2 g L−1) increased MB sorption from 10.6% to 73.1%, but decreased MB degradation from 80.7% to 41.1%, relative to nZOR/BC. Thus, CMC could increase MB sorption by electrostatic attraction and other possible mechanisms. The compromised MB degradation may be ascribed to reduced availability of hydroxyl and superoxide radicals to degrade MB, and increased band gap energy of ZnO.