Degradation Efficiency Of ZnO Research Articles

Construction of Ag-modified ZnO/g-C3N4 heterostructure for enhanced photocatalysis performance.

ZnO/g-C3N4 heterojunction modified with Ag nanoparticles (ZnO/CN/Ag) was synthesized by depositing ZnO nanorods/Ag nanoparticles onto g-C3N4 nanosheets. Under xenon lamp irradiation, 99% of Rhodamine B (RhB) was degraded by ZnO/CN/Ag-5% composite within 30min, which was much higher than the degradation efficiency of ZnO and ZnO/CN. The synergistic effect of g-C3N4 and ZnO, along with the localized surface plasmon resonance effect of Ag NPs, contributes to the improvement of photocatalytic performance. Ag nanoparticle provides another charge transfer path from g-C3N4 to ZnO, which speeds up the separation of electron-hole pairs. Meanwhile, the catalyst had good stability and recyclability. Finite-difference time-domain method and the density functional theory were used to obtain the charge transfer process. The photodegradation process has been studied in depth.

Diode characteristics, piezo-photocatalytic antibiotic degradation and hydrogen production of Ce3+ doped ZnO nanostructures

Piezo-photocatalysis of ZnO nanostructures had recently well attracted due to their exceptional potential in degrading the antibiotics and scalable hydrogen production. Here, we have synthesized the Ce3+ doped ZnO nanospheres in a facile wet chemical strategy. Dopant ions induced morphological evolution and optical bandgap tuning had observed in our experiment. Optical absorbance spectrum had confirmed the bandgap shortening occurs with Ce3+ doped ZnO specimens. The bandgap gap value had reduced to 2.82 eV from 3.05eV confirming the visible light responsivity of ZnO nano specimens. Obtained Zn(1-x)CexO nanospheres were utilized to fabricate the p-Si/n- Zn(1-x)CexO heterojunction diodes as well studied the improved electrical conductivity for the Ce3+ specimen-based diodes. Besides, ideality factor and barrier height values of the heterojunction diodes ZnO/p-Si, Zn0.99Ce0.01O/p-Si, Zn0.97Ce0.03O/p-Si, and Zn0.95Ce0.05O/p-Si are 15.97 & 0.43 eV, 15.47 & 0.44 eV, 8.02 & 0.46 eV and 5.21 & 0.47 eV, respectively. Direct sunlight assisted piezo-photocatalytic tetracycline (TC) degradation efficiency of ZnO, Zn0.99Ce0.01O, Zn0.97Ce0.03O, and Zn0.95Ce0.05O nanostructures respectively are 64%, 69%, 74% and 82%. We have produced the hydrogen quantity of 1234 μ mol h−1, 1490 μ mol h−1, 1750 μ mol h−1 and 1980 μ mol h−1 with 0%, 1%, 3% and 5% Ce3+ doped ZnO specimens under the direct sunlight assisted piezo-photocatalytic H2 production from H2S splitting.

One pot synthesis of Ag-Au/ZnO nanocomposites: a multi-junction component forsunlight photocatalysis

ABSTRACT Plasmonic nanoparticles nanoparticles incorporation increases the photo-physical conversion rate in the semiconductors. Here, we demonstrate the one-pot ZnO/(Ag-Au) nanocomposite for enhanced the visible light photocatalysis. The obtained ZnO nanoparticles are of 10–20 nm size and the deposited metal nanoparticles are of 1–3 nm. The light absorbance spectrum indicated the characteristic band edge absorbance of ZnO (~350 nm) as well as the SPR peaks of Ag (~420 nm) and Au (~520 nm). Enhanced absorption received for the metal nanoparticles deposited ZnO nanocrystals indicate the technological importance of the materials. Emission spectrum of the materials indicated the metal nanoparticles inhibited electron–hole pair recombination process. The photocatalytic methylene blue degradation efficiency of ZnO/(Ag-Au) (87%) nanocomposite is much higher than the ZnO/Ag (65%) and ZnO/Au (57%) nanocomposites. Studies indicated the performance improvement is due to the bimetallic nature over their pristine nature of Ag and Au.

Catalytic Degradation of Anionic Organic Dye on Greenly Synthesized CuO/ZnO Nanocomposites

CuO/ZnO nanocomposites were greenly prepared and tested for the catalytic degradation of methyl orange. The XRD analysis confirmed the existence of CuO and ZnO with crystallite sizes within the range of 15–30 nm. TEM and SEM images showed different morphological properties. The TGA analysis revealed a good thermal stability of the nanocomposite, with a total loss of less than 18% at a temperature of 700 °C. The nanocomposites were tested for the catalytic degradation of methyl orange under mild conditions with a catalyst mass/wastewater volume of 10 g/3 L, an initial dye concentration of 40 ppm, a pH of 4.5, and a degradation time of 3 h. The best efficiency of 49.1% was achieved by CuO nanoparticles (C), followed by 47.6%, which was obtained by 1C1Z. The degradation efficiency of ZnO (Z) was 16.4%, and it was increased by increasing the CuO precursor in the synthesis mixture, while adding ZnO to the CuO, resulting in a decrease in its catalytic performance.

Photodegradation of Bisphenol A with ZnO and TiO2: Influence of Metal Ions and Fenton Process

In this study, photocatalytic degradation of bisphenol A (BPA) was investigated using two types of catalysts (TiO2 and ZnO) with various metal ion concentrations and amounts of added H2O2. A kinetic test was performed to observe the changes of BPA over time under UV irradiation in a photocatalytic reactor. Experimental results demonstrated that degradation efficiency of ZnO was higher than that of TiO2. The degradation rate increased as catalyst dosage increased until reaching optimum dosage, after which degradation rate decreased. The addition of H2O2 improved the degradation efficiency of BPA, with the degradation efficiency increasing with the amount of H2O2. All metal ions, including Fe2+, Ni2+, and Cu2+, inhibited the degradation of BPA by ZnO at natural pH, whereas Fe2+ and Ni2+ enhanced degradation efficiency of BPA at acidic pH. Comparison of BPA degradation with H2O2 only, ZnO/H2O2, Fe2+/H2O2, and ZnO/Fe2+/H2O2 revealed that Fe2+/H2O2 was more efficient than other processes at lower pH (pH = 3.44), whereas ZnO/H2O2 the most efficient at higher pH (pH = 6.44). These results indicate that ZnO/H2O2 process was observed to be the most efficient of all processes. Degradation efficiency of BPA by ZnO was also influenced by additional parameters, including H2O2 concentration, metal ions, and solution pH.

Antituberculosis drugs degradation by UV-based advanced oxidation processes

Several advanced oxidation processes (AOPs) were investigated for the degradation of isoniazid (INH) and rifampicin (RIF) in aqueous solution: TiO2 and ZnO heterogeneous photocatalysis and homogeneous and heterogeneous UV-A photo-Fenton processes. Under optimized conditions (pH 6.0 and 500mgL−1 of photocatalyst) the UV-A TiO2-photocatalysis removed approximately 90% of INH and 60% of RIF at 60min. Under similar experimental conditions, the degradation efficiency of ZnO was significantly lower to INH. The low-cost UV-A homogeneous photo-Fenton process removed 70% of INH and 80% of RIF at 60min. Photo-Fenton process using iron-immobilized in chitosan beads showed lower degradation efficiency (7% to INH and 50% to RIF) probably due to low iron availability in the catalyst surface. A radical scavenging assay was performed to investigate the effect of free radicals (hydroxyl radical (OH), electron vacancy (hole, h+), superoxide radical anions (O2−), and singlet oxygen (1O2)) on INH and RIF degradation during TiO2/UV-A photocatalysis. The two drugs have distinct degradation mechanisms, while RIF is degraded by h+, INH suffers influence of various active species. The TiO2/UV-A photocatalysis was employed to degrade INH/RIF residue.