Ag/ZnO nanoparticles thin films as visible light photocatalysts (original) (raw)
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International Journal of Photoenergy, 2020
Zinc oxide (ZnO) has been known as an excellent photocatalyst for the degradation of a variety of organic pollutants under UV irradiation. This work describes a synthesis of ZnO nanoparticles via a facile precipitation method, and Ag was doped into Ag/ZnO nanocomposite to improve the photocatalytic degradation of BPA under visible light irradiation. The obtained ZnO nanoparticles were 20 nm in size and had a relatively high surface area and pore volume, 26.2 m2/g and 0.48 cm3/g, respectively. The deposition of Ag led to a decrease in the surface area, pore volume, and band gap energy ( E g ) of ZnO nanoparticles. However, the photocatalytic activity of Ag/ZnO composite in the case increased. The performance of ZnO was compared with Ag/ZnO composites at the different molar ratios, and the kinetic reaction of BPA in these catalysts was investigated by the first-order kinetic model. The sample of Ag/ZnO-10 composite had the highest catalytic activity and showed the degradation efficien...
Brazilian Journal of Physics
In this research, the photocatalytic activities of the samples were investigated against the pollutant methylene blue (MB) by the photodegradation process, where synthesized pure ZnO and ZnO:Ag (1%, 3%, and 5%) thin films were fabricated through a well-known technique such as successive ionic layer adsorption and reaction (SILAR). The microstructural, surface morphology, and optical properties of films were investigated using an X-ray diffractometer (XRD), Raman spectroscopy, scanning electron microscopy (SEM), UV-Vis, and photoluminescence (PL) spectroscopy. The diffraction pattern corresponded to the ZnO wurtzite crystalline phase, indicating that the samples were polycrystalline. Furthermore, increasing the Ag concentration causes the peaks to expand, indicating that doping reduces the crystallite size. According to SEM analysis, with the addition of doping, the morphological properties changed significantly, and the agglomeration was reduced. The UV-visible spectra suggest that the estimated optical band gap values of the ZnO:Ag thin films gradually decreased with Ag incorporation. Eventually, the kinetic results of methylene blue photodegradation reached 44.3% for ZnO thin films and 50.2%, 58.5%, and 75.8% for ZnO:Ag thin films. So, when exposed to UV light irradiation, the photocatalytic performance of ZnO:Ag films is significantly improved over that of undoped ZnO.
Synthesis and characterization of plasmonic visible active Ag/ZnO photocatalyst
Ag deposited ZnO nanoparticles (NPs) have been synthesized by simple sol-gel method for visible light active photocatalytic application. X-ray diffraction (XRD), TEM, UV-DRS and PL studies have been used to characterize the photocatalyst. The results show that Ag/ ZnO NPs are wurtzite phase (WZ) of ZnO with Ag NPs in the surface region forming a hetero-interface of Ag-WZ (ZnO). Visible light activity of the material has been studied using photocatalytic degradation kinetics of methylene blue as a probe pollutant. Ag/ZnO NPs exhibit five times higher visible-light driven photocatalytic activity than pristine ZnO and four times than the reference Degussa P-25, under identical conditions. The high visible activity of Ag/ZnO may be attributed to the surface plasmon effect complemented sensitization in the presence of metallic Ag and effective charge separation through Ag-WZ hetero-interfaces.
Applied Surface Science, 2019
Plasmonic metal-semiconductor nanostructures endow them with an enormous potential application in photocatalysis, however, the uniform deposition of metal NPs as small as a few nanometers remains a challenge. Here, we demonstrate the effectiveness of two-step polymer-network gel process in the synthesis of Ag-ZnO nanocatalyst with superior photocatalytic properties. Because of uniform distributed Ag NPs, large specific surface area and abundant surface oxygen vacancies, the Ag-ZnO nanoparticles exhibit a super high photocatalytic efficiency in comparison to pure ZnO nanoparticles. The efficiency can be further improved by optimizing the external factors, such as catalyst dosage, ambient temperature and initial solution pH. Good stability and practicability indicate its potential application in environmental purification. Our work does not only provide a feasible strategy for the synthesis of high property Ag-ZnO nanophotocatalysts, but also enriches the understanding of metal-metal oxide nanostructures.
Catalysts
Wastewaters of the textile industry, e.g., those generated in Gresik, Indonesia, are a possible threat to the environment and should be treated before disposal. Photodegradation is a more promising method to overcome this problem than conventional methods such as biodegradation. ZnO is widely used for photodegradation due to its unique physical and chemical properties and stability. In this study, Ag was loaded onto ZnO, which is non-toxic and inexpensive, can improve the electron–hole separation, and has a significant catalytic potential. Pristine ZnO and ZnO-Ag nanoparticles were fabricated by an ultrasonic spray pyrolysis system at different Ag contents (1, 5, and 10 wt%). The carrier gas ratio (O2:N2) was also changed (1:0, 1:2, 1:1, 2:1, and 0:1) to examine its effects on the nanoparticle characteristics. The nanoparticle characteristics were examined using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Brunauer, Emmett,...
Results in Physics, 2019
Zinc oxide (ZnO) is one of the potential semiconductors for photocatalytic applications. However, ZnO has a high recombination rate between electrons and holes, which reduces the efficiency of its photocatalytic activity. Thus, a nanohybrid structure between ZnO and a noble metal, such as Ag, has been proposed because it is cost effective, is chemically stable, and has enhanced photocatalytic activity. In general, ZnO/Ag nanohybrids are not easily synthesized due to the self-nucleation of Ag NPs during the deposition on ZnO. In this study, the Ag nanoparticles were deposited on the ZnO nanorods (NRs) prepared on glass substrate by using the facile and rapid hydrothermal method at low temperature 80°C for 90 min. The result analysis shows that the Ag nanoparticles deposition process did not change the morphological and microstructural properties of the ZnO NRs. The Ag NPs with the diameter range of 10-20 nm spread uniformly on the surface of the ZnO NRs. The photodegradation efficiency of methyl blue using the ZnO/Ag nanohybrids was higher than pure ZnO NRs. The ease of electron transfer between the ZnO and the Ag NPs was a major cause of the increased photocatalytic activity in both UV and visible-light irradiation.
Synthesis and enhancement of photocatalytic activities of ZnO by silver nanoparticles
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2014
h i g h l i g h t s Synthesis of Ag-ZnO composite in ethanol-water mixture is reported. Method is simple, novel, non-toxic and cost effective without use of surfactant. The composite showed high photocatalytic activity than bare ZnO towards Rh. B. The results of XRD, DRS, PL, TEM and PSD are good agreement. g r a p h i c a l a b s t r a c t Mechanism elaborating photocatalytic activity.
Advanced Powder Technology
Ag/Ag 2 S-ZnO nanocomposites were prepared via a simple hydrothermal process followed by a plasmonic Ag + reduction through a photo-deposition method. Ag 2 S was introduced to narrow the overall composite bandgap and activate the surface plasmon resonance (SPR) effect of the Ag + cation present. The physicochemical properties of the as-synthesised catalysts were characterised by X-ray diffraction (XRD), scanning and transmission electron microscopies (SEM and TEM), Brunauer-Emmett-Teller (BET) analysis. Fourier-transform infrared spectroscopy (FTIR), Ultraviolet diffuse reflectance spectroscopy (UV-vis DRS), photoluminescence emission spectra (PL) and X-ray photoelectron spectroscopy (XPS) was conducted to investigate the photo-absorption and emission spectra of the nanocomposites. The degradation efficiency of all the synthesised catalysts (ZnO, Ag 2 S, Ag/ZnO and Ag 2 S/ZnO) prior to the final product, Ag/ Ag 2 S/ZnO was tested and compared. Results showed that the ternary Ag/Ag2S/ZnO achieved a 98 % phenol removal compared to 50 %, 11 %, 64 % and 93 % for ZnO, Ag2S, Ag/ZnO and binary Ag2S/ZnO, respectively. The degradation kinetics followed the Langmuir-Hinshelwood model, which typically describes heterogeneous photocatalytic surface reactions. The linear fits had R 2 values higher than 0.97, which confirms the degree of accuracy or statistical fitness to the kinetic model. Degradation scavenger test confirmed the holes (h +) as the main inhibitor and identified the superoxide O 2 radical as the main active specie responsible for the degradation. Total organic carbon analysis using the ternary Ag/Ag 2 S-ZnO catalyst only achieved a 74% phenol mineralization after 24 h of photocatalysis. Recyclability tests showed good phenol removal stability of Ag/Ag 2 S-ZnO at 41 % after five recycle runs. Hence, a synergistic degradation mechanism responsible for the efficient photo-degradation performance was proposed.
Chemical engineering transactions, 2021
Silver sulphide (Ag2S) and zinc oxide (ZnO) nanoparticles were synthesized through a sol-gel method. The Ag constituent of the ternary was achieved by photodesposition of the binary Ag2S/ZnO resulting in a color change from brownish grey to purple indicating its formation. The synthesised particles were characterised using Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and Energy-dispersive X-ray spectroscopy (EDX) to confirm its elemental presence and morphology. The crystallinity of the nanoparticles was determined using the X-ray diffractometer (XRD), and Brunauer–Emmett–Teller (BET) analysis surface area was 4.95 m2g-1. The progressive degradation of phenol was analysed and results showed that under visible light, the ternary composite Ag/Ag2S/ZnO, exhibited the highest phenol degradation efficiency (95 %) compared to the constituent compounds, ZnO (37 %) and Ag2S/ZnO (83 %) after 6 h of visible light irradiation respectively. However, investigations ...