Enhanced Photocatalytic Activity Based on Composite Structure with Downconversion Material and Graphene

Facile Synthesis of Barium-Doped Cadmium Sulfide Quantum Dots for the Treatment of Polluted Water: Experimental and Computational Investigations

In this study, cadmium sulfide (CdS) quantum dots (QDs) and barium (Ba) (3 and 6 wt %)-doped CdS QDs were synthesized via a hydrothermal technique. The basic purpose of this work is to degrade methylene blue (MB) dye and evaluate density functional theory (DFT). The synthesized samples were characterized through X-ray powder diffraction (XRD), selected area electron diffraction (SAED), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), high-resolution transmission electron microscopy (HR-TEM), UV-vis spectrophotometer, PL, and density functional theory (DFT). The XRD (structural analysis) confirmed that the hexagonal crystal structure and crystallinity increased upon doping. Selected area electron diffraction (SAED) analysis confirmed the polycrystalline nature of the prepared QDs. The functional groups have been investigated using FTIR analysis. The surface and structural morphologies of the synthesized specimen have been investigated by applying TEM and FE-SEM, and it was found to exhibit the topology of QDs. In addition, optical characteristics have been investigated via UV-vis absorption spectroscopy, which exhibited a bathochromic shift (red shift) as a consequence of the reduction of the band-gap energy upon doping from 2.56 to 2.38 eV. PL analysis was used to observe the electron-hole recombination rate. Moreover, the electronic and optical properties of Ba-doped CdS were further explored using density functional theory. Pristine and Ba-doped QDs exhibit sufficient catalytic activity (CA) against the MB dye in all media as 62.59, 70.15, and 72.74% in neutral, basic, and acidic solutions, respectively.

Synthesis, characterization and photocatalytic properties of nanostructured lanthanide doped β-NaYF4/TiO2 composite films

The photocatalytic approach is known to be one of the most promising advanced oxidation processes for the tertiary treatment of polluted water. In this paper, β-NaYF₄/TiO₂ composite films have been synthetized through a novel sol–gel/spin-coating approach using a mixture of β-diketonate complexes of Na and Y, and Yb³⁺, Tm³⁺, Gd³⁺, Eu³⁺ as doping ions, together with the TiO₂ P25 nanoparticles. The herein pioneering approach represents an easy, straightforward and industrially appealing method for the fabrication of doped β-NaYF₄/TiO₂ composites. The effect of the doped β-NaYF₄ phase on the photocatalytic activity of TiO₂ for the degradation of methylene blue (MB) has been deeply investigated. In particular, the upconverting TiO₂/β-NaYF₄: 20%Yb, 2% Gd, x% Tm (x = 0.5 and 1%) and the downshifting TiO₂/β-NaYF₄: 10% Eu composite films have been tested on MB degradation both under UV and visible light irradiation. An improvement up to 42.4% in the degradation of MB has been observed for the TiO₂/β-NaYF₄: 10% Eu system after 240 min of UV irradiation.

Preparation of High Mechanical Performance Nano-Fe₃O₄/Wood Fiber Binderless Composite Boards for Electromagnetic Absorption via a Facile and Green Method

Fe₃O₄/wood fiber composites are prepared with a green mechanical method using only distilled water as a solvent without any chemical agents, and then a binderless composite board with high mechanical properties is obtained via a hot-press for electromagnetic (EM) absorption. The fibers are connected by hydrogen bonds after being mechanically pretreated, and Fe₃O₄ nanoparticles (NPs) are attached to the fiber surface through physical adsorption. The composite board is bonded by an adhesive, which is provided by the reaction of fiber composition under high temperature and pressure. The Nano-Fe₃O₄/Fiber (NFF) binderless composite board shows remarkable microwave absorption properties and high mechanical strength. The optional reflection loss (RL) of the as-prepared binderless composite board is -31.90 dB. The bending strength of the NFF binderless composite board is 36.36 MPa with the addition of 6% nano-Fe₃O₄, the modulus of elasticity (MOE) is 6842.16 MPa, and the internal bond (IB) strength is 0.81 MPa. These results demonstrate that magnetic nanoparticles are deposited in binderless composite board by hot pressing, which is the easiest way to produce high mechanical strength and EM absorbers.

Fabrication of TiO2 Nanosheet Aarrays/Graphene/Cu2O Composite Structure for Enhanced Photocatalytic Activities

TiO₂ NSAs/graphene/Cu₂O was fabricated on the carbon fiber to use as photocastalysts by coating Cu₂O on the graphene (G) decorated TiO₂ nanosheet arrays (NSAs). The research focus on constructing the composite structure and investigating the reason to enhance the photocatalytic ability. The morphological, structural, and photocatalytic properties of the as-synthesized products were characterized. The experimental results indicate that the better photocatalytic performance is ascribed to the following reasons. First, the TiO₂ NSAs/graphene/Cu₂O composite structure fabricated on the carbon cloth can form a 3D structure which can provide a higher specific surface area and enhance the light absorption. Second, the graphene as an electron sink can accept the photoelectrons from the photoexcited Cu₂O which will reduce the recombination. Third, the TiO₂ nanosheet can provide more favorable carrier transportation channel which can reduce the recombination of carriers. Finally, the Cu₂O can extend the light absorption range.

One-pot hydrothermal synthesis of CdS decorated CuS microflower-like structures for enhanced photocatalytic properties

CdS decorated CuS structures have been controllably synthesized through a one-pot hydrothermal method. The morphologies and compositions of the as-prepared samples could be concurrently well controlled by simply tuning the amount of CdCl2 and thiourea. Using this strategy, the morphology of the products experienced from messy to flower-like morphologies with multiple porous densities, together with the phase evolution from pure CuS to the CdS/CuS composites. Serving as a photocatalyst, the samples synthesized with the addition of 1 mmol cadmium chloride and 3 mmol thiourea during synthetic process, showed the best photocatalytic activity, which could reach a maximum photocatalytic efficiency of 93% for methyl orange (MO) photodegradation after 150 min. The possible mechanism for the high photocatalytic efficiency of the sample was proposed by investigating the composition, surface area, structure, and morphology before and after photocatalytic reaction.

Hybrid nanostructures of TiO2 nanorod array/Cu2O with a CH3NH3PbI3 interlayer for enhanced photocatalytic activity and photoelectrochemical performance

A novel composite photocatalyst constructed from TiO₂ NRAs, CH₃NH₃PbI₃ and Cu₂O exhibits highly efficient visible light photocatalysis activity.