Muhammad Fahad Ehsan

Preparation of 2D hydroxyl-rich carbon nitride nanosheets for photocatalytic reduction of CO2

Hydroxyl-rich g-C3N4 nanosheets were prepared by ultrasonic exfoliation of bulk g-C3N4 in water. The samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, atomic force microscopy, UV-vis absorption spectroscopy, photoluminescence spectroscopy, time-resolved fluorescence decay spectroscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy and photocurrent response. The results indicated that the bulk g-C3N4 was exfoliated to five or six layers. The specific surface area increased from 8.66 m2 g−1 for the bulk g-C3N4 to 26.48 m2 g−1 for the nanosheets. More importantly, the amount of hydroxyl group on the g-C3N4 surface increased greatly upon ultrasonic treatment in water. Meanwhile, the separation rate of charge carriers was improved greatly and the conduction band potential shifts to a more negative value. All these can explain the enhanced activity of g-C3N4 nanosheets for visible-light photocatalytic reduction of CO2.

Preparation and characterization of SrTiO3–ZnTe nanocomposites for the visible-light photoconversion of carbon dioxide to methane

Limited fossil fuel resources and increasingly stringent requirement of environmental protection from major greenhouse gases, including carbon dioxide (CO2), which results directly from the burning of fossil fuels, energy savings and greenhouse-effect alleviation have emerged as major global concerns. The development of an “artificial photosynthetic system” (APS) having both the analogous important structural elements and the reaction features of photosynthesis to achieve solar-driven water splitting and CO2 reduction is highly challenging. Herein, it has been demonstrated that SrTiO3–ZnTe can be utilized as an efficient APS for the photoreduction of CO2 into methane (CH4) under visible-light irradiation (≥420 nm). The results indicate that the combination of ZnTe with SrTiO3 visibly increases the formation of CH4 by efficiently promoting electron transfer from the conduction band of ZnTe to that of SrTiO3 under visible-light irradiation, and thereby demonstrate this to be a promising candidate for the photocatalytic conversion of CO2 into hydrocarbon fuels.

Hollow and mesoporous ZnTe microspheres: synthesis and visible-light photocatalytic reduction of carbon dioxide into methane

Hollow and mesoporous microstructures have been found to be an attractive class of materials due to their superior physical properties and potential applications. In the present work, a hydrothermal method has been used to synthesize hollow and mesoporous ZnTe hierarchical microspheres. The as-synthesized microspheres are characterized by a variety of techniques, including X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, high resolution transmission electron microscopy, X-ray photoelectron spectroscopy and ultraviolet-visible spectroscopy. Nitrogen adsorption–desorption measurements and the curve of relative pore size distribution via Brunauer–Emmett–Teller analysis confirm the existence of mesopores in the obtained nanomaterials. Different reaction parameters such as NaOH concentration, reaction temperature and time, and concentration of the tellurium precursor have been studied and the detailed growth mechanism has been proposed. These hollow and mesoporous microspheres are also used for the photoreduction of carbon dioxide into methane under visible-light illumination (λ ≥ 420 nm) with a solar energy conversion efficiency of 0.072%.

Synthesis of a Bi2S3/CeO2 nanocatalyst and its visible light-driven conversion of CO2 into CH3OH and CH4

Due to shortage of fossil fuels and rapid growth of energy demand, exploration of new energy resources becomes essential. Moreover, the CO2 level is increasing day by day, which has caused global warming as well as environmental pollution. Designing a suitable photocatalyst that can solve both issues always remains a challenge. In this work, we have designed such a nanocatalyst that may be helpful in solving these issues. A hydrothermal method has been used for the synthesis of Bi2S3 and CeO2, and their nanocomposite (Bi2S3/CeO2) has been prepared by a two-step method. X-ray diffraction results confirm the formation of the target materials. High resolution transmission electron microscopy and scanning electron microscopy show that Bi2S3 is rod-shaped and CeO2 is in the form of spherical particles. Both Bi2S3 and CeO2 are well distributed in the nanocomposite. The optical properties of the obtained nanocatalysts are analyzed by UV/visible absorption spectroscopy and photoluminescence spectroscopy. X-ray photoelectron spectra are used to determine the position of the valence band. All the synthesized materials are applied to the photoreduction of CO2 with water under visible-light irradiation (λ ≥ 420 nm). The Bi2S3/CeO2 nanocomposite exhibits higher yields of methane and methanol than the individual semiconductors. Moreover, the nanocomposite shows improved stability compared to the individual catalysts.

Biocompatibility of cobalt iron oxide magnetic nanoparticles in male rabbits

Present study was conducted to study the in vivo biocompatibility of cobalt iron oxide magnetic nano-particles (CoFe2O4 MNPs) in rabbits. CoFe2O4 MNPs were synthesized by the conventional micro emulsion technique in crystallite size range of 30 to 50 nm. The lattice constant (a) and cell volume were found to be 8.386 Å and 589.75 Å3, respectively, revealed by XRD. Subject animals were divided in three groups—low dose, high dose and control group without nanoparticles implantation for biocompatibility evaluation. CoFe2O4 was intraperitoneally implanted in rabbits: low dose (1mg CoFe2O4/Kg body weight) and high dose (10mg CoFe2O4/Kg body weight). Blood, serum and histological study of vital organs (liver, heart, kidney and spleen) were carried out in seven days of time protocol after sacrificing of animals. Results indicated that CoFe2O4 had drastically affected the blood chemistry in a dose-dependent manner as RDWa (P=0.01), Platelet (P<0.001) and Plateletcrit (P<0.001) concentrations reduced significantly in low dose and high dose CoFe2O4 treatments as compared to sham treated control group. Histological analysis revealed that CoFe2O4 exposure resulted in disordered and abnormal histology of liver, kidney and that of muscles at surgical site. It is concluded that CoFe2O4 has low biocompatibility and higher toxicity levels in living system at the applied doses.

Visible-Light Photoreduction of CO2 into CH4 over ZnTe-Modified TiO2 Coral-Like Nanostructures

Rapidly depleting fossil fuels and the related environmental issues are two alarming global concerns the world is facing today. To address these issues efficiently, future energy requirements need to be fulfilled by renewable and environmentally friendly resources. In this context, we report the ZnTe-modified TiO2 photocatalysts with varying amounts of ZnTe (1.96, 16, and 65 %) for the photoreduction of carbon dioxide into methane under visible light. The hydrothermally synthesized photocatalysts have been characterized by using various techniques, such as X-ray diffraction, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy, transmission electron microscopy, UV/Vis spectroscopy, X-ray photoelectron spectroscopy and Brunauer-Emmett-Teller (BET) analysis for surface-area measurements. The photocatalyst with 1.96 % ZnTe shows the best results, which are attributed to its high BET specific surface area and the formation of a heterojunction at the interface, which can facilitate efficient charge transfer.

Synthesis and characterization of polyaniline/Zr-Co-substituted nickel ferrite (NiFe1.2Zr0.4Co0.4O4) nanocomposites: their application for the photodegradation of methylene blue

AbstractIn the present work, different composites of polyaniline (PANI) with various contents of Zr-Co-substituted nickel ferrite with formula (NiFe1.2Zr0.4Co0.4O4) (12.5, 25, 37.5, and 50% w/w) nanoparticles (NPs) were synthesized. These composites were characterized by X-ray diffraction (XRD), UV/Visible, Brunauer–Emmett–Teller (BET), X-ray photoelectron spectrometer (XPS), and scanning electron microscopy (SEM) analysis, and are used for the photodegradation of methylene blue (MB) from aqueous media. Effects of reaction time, NPs concentration, and degradation kinetics studies have been investigated. The structure of nickel ferrite was confirmed by XRD analysis while surface area, pore size, and morphology were investigated by BET and SEM analyses. The elements oxidation states were confirmed by XPS analysis while the optical studies were investigated by UV/Visible analysis. The degradation rate was observed fast at initial stages and then became slow. The degradation of MB follows the first-order kine...

Congo red photomineralization over Co 3 O 4 /CoTe common cation nanocomposites

Due to increasing energy demands and environmental pollution, it is need of the hour to develop some eco-friendly technologies that can overcome these two major issues. Nanotechnology and photocatalysis provide the best solution for the energy crisis and environmental pollution. Here, in this work, we report metal oxide (Co3O4), metal chalcogenide (CoTe) and their nanocomposites (Co3O4/CoTe) to benefit from synergy attributed to their unique electronic properties for the photocatalytic degradation of Congo red dye, which is a major industrial pollutant. The hydrothermally synthesized photocatalysts are further characterized via various techniques including powder X-ray diffraction, scanning electron microscopy coupled with energy dispersive X-ray spectroscopy and UV–Visible diffused reflectance spectroscopy (DRS) which endorse their successful synthesis. Amongst the as-synthesized photocatalysts, the nanocomposites exhibited better photocatalytic activity as compared to their individual counterparts which is hereby attributed to reduced charge recombination, suitable band alignment in the heterostructure as well as to the presence of common cation.

Visible-light active tin selenide nanostructures: synthesis, characterization and photocatalytic activity

A simple approach to synthesizing tin selenide nanostructures showing superior photocatalytic performance with variable tin ratios via a facile chemical method is reported in this study. The crystalline phase, morphology, oxidation states of elements, surface composition and optical properties of the photocatalysts were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and UV-vis spectroscopy, respectively. The photocatalytic activity was evaluated by the degradation of methylene blue (MB) under visible-light irradiation, indicating that SnSe exhibits excellent photocatalytic performance with a maximum % degradation efficiency of MB up to 92.91% after 40 min of light irradiation. These materials were also used as photocatalysts for the degradation of Congo red (CR) and the results showed 98% degradation of Congo red which is much higher than other photocatalysts. The possible degradation pathway is also presented. Indeed, SnSe nanostructures with variable tin ratios behaved as highly efficient photocatalysts and could be promising for future industrial applications for wastewater treatment.