Structural, Optical, and Renewable Energy-Assisted Photocatalytic Dye Degradation Studies of ZnO, CuZnO, and CoZnO Nanostructures for Wastewater Treatment

Renewable energy can be harnessed from wastewater, whether from municipalities or industries, but this potential is often ignored. The world generates over 900 km3 of wastewater annually, which is typically treated through energy-consuming processes, despite its potential for energy production. Environmental pollution is a most important and serious issue for all and their adulterations to the aquatic system are very toxic in very low concentrations. Photocatalysis is a prominent approach to eliminating risky elements from the environment. The present study developed Zinc oxide (ZnO), Copper-doped Zinc oxide (CuZnO), and Cobalt-doped Zinc oxide (CoZnO) nanostructures (NSs) by facile hydrothermal route. The crystalline and structural stability of the synthesized nanostructures were evident from XRD and FESEM analysis. Metal, and oxygen bond and their interaction on the surfaces and their valency were explored from XPS spectra. Optical orientations and electron movements were revealed from UV-Visible analysis. After 100 min exposure time with 1 g of catalyst concentration 60%, 70%, and 89% of dye degraded, for dye concentration (5 mg/L to 50 mg/L), the huge variation observed (70% to 22%), (80% to 16%), (94% to 10%). The highest photodegradation rate (55%, 75%, 90%) was observed on pH~12 using ZnO, CoZnO, and CuZnO respectively. Photodegradation of methylene blue confirmed the largest surface area, rate of recombination, photo-excited charge carriers, photo-sensitivity range, and radical generations of ZnO, CuZnO, and CoZnO. The present study, therefore, suggested that CuZnO would be preferred to produce nanomaterials for industrial wastewater treatment like methylene

Vacuum annealing temperature on spray In

Indium sulfide In2S3 thick films are deposited on glass substrates using spray technique over the optimum conditions experiments (Ts = 340 °C, S/In = 2). The films are polycrystalline and have thickness of about 1.8 μm. These films are annealed in a vacuum sealed pyrex tubes (10−5 torr). Physico-chemical characterizations by SEM observation, X-ray diffraction and EDX analysis are undertaked on these films. This treatment has improved crystallinity of samples. It has allowed thus to stabilize β and γ varieties of In2S3 material. In2O3 and In6S7 phases have appeared with very weak intensities at high temperatures. The best structure quality are obtained at 300 °C for the optimum annealed temperature (Ts = 340 °C, S/In = 2), for which samples are constituted in dominance by γ phase oriented preferentially towards (1 0 2). The grain size is 42 nm of this phase. Chemical composition of such films has changed relatively to non-treated film but it seems not be affected by treatment temperature. Atomic molar ratio S/In is obtained for 0.9. Optical study shows that these layers are transparent in the visible and optical direct band gap increases as function of annealed temperature

Synthesis and Characterization of New Imidazole Phthalocyanine for Photodegradation of Micro-Organic Pollutants from Sea Water

In this study, a series of new metal phthalocyanines with imidazole function MPc(Imz) (M: Cd, Hg, Zn and Pd) were synthesized to improve the photocatalyst performances. All physical properties such as total energy, HOMO, LUMO energies of MPc(Imz), as well as their vibrational frequencies have been determined by DFT method using B3LYP theory level at 6-311G (d, p) and sdd basis set. The gap of energy level between work function (WF) of ITO and LUMO of PdPc(Imdz) was 1.53 eV and represents the highest barrier beneficial to electron injection compared to WF of ZnPc(Imz), HgPc(Imz), and CdPc(Imz). Furthermore, the PdPc(Imdz) thin films on indium tin oxide (ITO) glass were prepared by spin coating and vacuum evaporation technique, and were characterized by X-ray diffraction (XRD), surface electron morphology (SEM), atomic force microscopy (AFM), and UV–Vis spectroscopy. The photocatalytic activity of the ITO/glass supported thin films and degradation rates of chlorinated phenols in synthetic seawater, under visible light irradiation were optimized to achieve conversions of 80–90%. Experiments on synthetic seawater samples showed that the chloride-specific increase in photodegradation could be attributed to photochemically generated chloride radicals rather than other photoproduced reactive intermediates [e.g., excited-state triplet PdPc(Imz) (3PdPc(Imz)*), reactive oxygen species]. The major 2,3,4,5-Tetrachlorophenol degradation intermediates identified by gas chromatography-mass spectrometry (GC/MS) were 2,3,5-Trichlorophenol, 3,5-dichlorophenol, dichlorodihydroxy-benzene and 3,4,5-trichlorocatechol

Design and Optimization of One-Dimensional TiO2/GO Photonic Crystal Structures for Enhanced Thermophotovoltaics

In this paper, we theoretically explore the spectroscopic features of various one-dimensional photonic crystal (1D-PC)-based spectrally selective filters. The 1D-PC structure is composed of alternating layers of titanium dioxide (TiO2) and graphene oxide (GO). Employing the transfer matrix method (TMM), the impacts of the incidence angle, the number, and thicknesses of TiO2/GO layers in various 1D-PC stacks on the spectroscopic features of the filters are explored in detail. The proposed 1D-PC structures are designed for practical use for thermophotovoltaic (TPV) applications to act as filters that selectively transmit light below 1.78 μm to a GaSb photovoltaic cell, while light with longer wavelengths is reflected back to the source. The optimal design presented here consists of two Bragg quarter-wave 1D-PC filters with different central frequencies stacked to form a single structure. We demonstrate that our optimized 1D-PC filter exhibits a large omnidirectional stop band as well as a broad pass band and weak absorption losses. These features meet the fundamental exigencies to realize high-efficiency TPV devices. Additionally, we show that when integrated in a TPV system, our optimized filter leads to a spectral efficiency of 64%, a device efficiency of 39%, and a power density of 8.2 W/cm2, at a source temperature of 1800 K

Physical and Dielectric Properties of Ni-Doped In2S3 Powders for Optical Windows in Thin Film Solar Cells

This paper reports the effect of Nickel (Ni) on indium sulfide (In2S3) powder. This work presents a systematic study of the physical and dielectric properties of In2-xS3Nix powders with 0, 2, 4, and 6 at.% of nickel. Doped and undoped samples were investigated by X-ray powder diffraction (XRD), energy dispersive X-ray spectroscopy, thermal gravimetric analysis, Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM), and impedance spectroscopy. XRD patterns revealed that each In2-xS3Nix composition was crystalline, which was also confirmed by the FTIR results. The presence of Ni in the samples was confirmed by energy dispersive spectroscopy (EDS). The Raman studies show different peaks related to the In2S3 phase and do not reveal any secondary phases of In–Ni and Ni–S. The SEM images of the undoped and Ni-doped In2S3 samples indicated a correlation between dopant content and the surface roughness and porosity of the samples. The impedance analysis indicated semiconductor behavior present in all samples, as well as a decrease in resistance with increasing Ni content. This work opens up the possibility of tailoring the properties and integrating Ni-doped In2S3 nanocomposites as thin film layers in future solar cells

Molar ratio S/In effect on properties of sprayed In

We have studied the structural, morphological and optical properties of In2S3 layers deposited on glass substrate by the spray pyrolysis method with the molar ratio S/In varies from 1 to 4. The substrate temperature was maintained at 613 K. The characteristics of these films have been determined by X-ray diffraction (XRD), optical absorption-transmission and atomic force microscopy (AFM). Their structure is strongly dependent on the molar ratio. The deposit is mainly constituted by the β phase towards (4 0 0) direction. No characteristic peaks were observed for other impurities such as In2O3, S or In2(OH)3. The best crystallinity and surface morphology are obtained at molar ratio equal to 2.5. At this ratio, the crystallites coalesce and the local roughness is of the order of 1 nm. Optical transmission of 80% has been achieved in the visible spectrum. In2S3 band gap energy reached 2.63 eV from layers with x = 2 and deposited at Ts = 613 K

Experimental and Theoretical Studies on Optical Properties of Tetra(Imidazole) of Palladium (II) Phthalocyanine

In this work, the optical properties of tetra(imidazole) of palladium phthalocyanine (PdPc(Im)4) in solution form and thin films on glass and fluorine-doped tin oxide (FTO) substrates were investigated via the thermal evaporation technique. The optical band gap was evaluated by ultraviolet–visible spectroscopy (UV-Vis). The energy band gap values were determined based on the Tauc graph. In addition, time-dependent density functional theory (TD-DFT) was used to simulate the UV-Vis absorption spectrum of the (PdPc(Im)4) molecule in the Dimethyl Sulfoxide (DMSO) solution phase. A good correlation was found between the DFT results and the experimental optical results. The band gap values between the experimental and DFT-simulated values are presented. The energy band gap of (PdPc(Im)4) obtained from the DFT calculations showed that it can be efficiently regulated. Frontier molecular orbitals and molecular electrostatic potentials were also proposed in this work. The surface study of the layers deposited on FTO was considered by atomic force microscopy (AFM) and scanning electron microscopy (SEM), and the results demonstrated good homogeneity covering the entire surface. The SEM image showed a homogeneous distribution of the grains with some spherical or rod-shaped structures and no agglomeration structures. This work rendered a strategy for regulating the energy band gap and compared the experimental observations obtained with theoretical studies, which provides a fundamental insight into the optical band for optoelectronic and thin-film solar cells