In this report, we present a new approach for the fabrication and application of Cs4PbBr6 microcrystals (Cs4PbBr6 MCs). The Cs4PbBr6 MCs are synthesized via an anti-solvent induced crystallization of PbBr2:CsBr directly in dimethylsulfoxide (DMSO) by introducing HBr (HBr, 48% aqueous solution). The ratio of HBr and DMSO plays a vital role in the formation of Cs4PbBr6. By controlling the HBr/DMSO ratio, pure Cs4PbBr6 or the CsPbBr3 phase can be obtained. The Cs4PbBr6 MCs were initially obtained by adding HBr to CsBr:PbBr2/DMSO. However, on increasing the amount of the added HBr, Cs4PbBr6 MCs were converted to CsPbBr3 MCs and the photoluminescence (PL) disappeared. It was also found that CsPbBr3 MCs can be transformed to Cs4PbBr6 MCs by simply adding DMSO to the dried CsPbBr3 MCs. The Cs4PbBr6 MCs exhibit a strong PL at 516 nm with a full width at half-maximum of 25 nm …
In this research, we investigate the effect of metal doping on the electrochromic (EC) performance of tungsten trioxide (WO3) films. These films were prepared by a novel method involving solution processing and thermal annealing. In this procedure, ammonium tetrathiotungstate ((NH4)2WS4) was dissolved in dimethylformamide at a high concentration ratio (200 mg mL−1) to obtain a homogeneous solution and then spin-coated onto the indium thin oxide (ITO) substrate for use as a working electrode. Subsequently, the film was annealed at the different temperatures (200, 300, 400, and 500 °C) to form a crystal structure of WO3. X-ray diffraction, Raman, and X-ray photoelectron spectroscopic results confirm the crystal formation of WO3. Moreover, in order to improve the electrochromic performance, different concentrations (10, 20, 30, and 40 mM) of different metal chlorides such as PtCl4, PdCl2, AuCl3, AgCl …
Organic–inorganic halide perovskite materials have attracted significant attention during the last few years because of their superior properties for electronic and optoelectronic devices, such as their long charge‐carrier diffusion lengths and high photoluminescence quantum yields of up to 100% with tunable bandgaps over the entire visible spectral range. In addition to solar cells, light‐emitting diodes represent a fascinating application for halide perovskite materials. Here, the recent progress relating to halide perovskite LEDs is reviewed. The current strategies for improving the performance of halide LEDs, focusing on morphological engineering, dimensional engineering, compositional engineering, surface passivation, interfacial engineering, and the plasmonic effect are discussed. The challenges and perspectives for the future development of halide perovskite LEDs are also considered.
We demonstrate a facile and efficient method for the synthesis of a metal-doped WS2nanoflower (NF) catalyst. We also report its application for the electrocatalytic hydrogen evolution reaction (HER). The flower-like WS2 particles were produced by a hydrothermal reaction, and, subsequently, the WS2 was doped with metal chlorides such as AuCl3, AgCl, PtCl2, and PdCl2, followed by reduction with sodium borohydride to form metal-doped WS2 NFs. The Pd-doped WS2 NF catalyst showed a high HER performance, having a Tafel slope of 54 mV/dec and an overpotential of -175 mV at −10 mA cm−2. The improvement is attributed to the energy band alignment near the H+/H2reduction potential and the large surface area of the WS2 NFs.
Nanocrystal quantum dots (QDs) provide tunable optoelectronic properties on the basis of their dimension. CdSe QDs, which are size-dependent colloidal nanocrystals, are used for efficient electrochromic devices owing to their unique properties in modulating quantum confinement, resulting in enhanced electron insertion during the electrochromic process. Incorporating a well-known metal oxide electrochromic material such as WO3 into CdSe QDs enhances the redox process. Herein, we propose a facile method for producing and optimizing CdSe QDs doped in WO3. The fabrication of the electrochromic film involves a solution and annealing process. Moreover, the effect of the QD size to optimize the electrochromic layer is studied. As a result, the coloration efficiency of WO3 and optimized CdSe QD–WO3 are obtained as 68.6 and 112.3 cm2/C, respectively. Thus, size-tunable nanocrystal QDs combined with a …
Recently, quantum dot light‐emitting devices have drawn significant attention in the field of display technologies due to their low power consumption, high color purity, and solution processability. Among these, halide perovskite quantum dots (HPQDs) have emerged as the most efficient quantum dots for light‐emitting applications, with photoluminescence quantum yields (PLQYs) approaching 100%. In this Review, the current progress of HPQDs, including their synthesis, properties, and applications in light‐emitting devices, are summarized and discussed. First, the optical and physical properties of HPQDs and their advantages as emissive layers in light‐emitting devices are discussed. Next, synthetic strategies for the synthesis of high‐quality and high‐PLQY HPQDs are introduced. Subsequently, critical parameters affecting the properties and structures of HPQDs, such as the role of surface passivation, fast anion …
Description Two-dimensional transition metal dichalcogenides (2D-TMDs), such as MoS2 and WS2 nanosheets (MeS2-NS), are reported as efficient catalysts for hydrogen evolution reaction (HER), which can potentially replace the expensive platinum catalyst. In this report, 1T phase MeS2 (1T-MeS2) NS are synthesized by lithium-intercalation exfoliation method, subsequently being modified by amorphous MoSx and WSx (MeSx@MeS2-NS) through a solvothermal method. Interestingly, MeSx@MeS2-NS significantly improves the HER performance compared with bare MeS2-NS as catalysts. Among these, MoSx@MoS2 is observed to be the best combination for HER, with an onset potential and Tafel slope of 114 mV and 45.1 mV decade−1, respectively. The enhancement in the HER device using MeSx@MeS2-NS as the catalyst originates from vertically grown MeSx, which provides additional active sulfur sites for the …
There has been considerable research to engineer composites of transition metal dichalcogenides with other materials to improve their catalytic performance. In this work, we present a modified solution-processed method for the formation of molybdenum selenide (MoSe 2) nanosheets and a facile method of structuring composites with graphene oxide (GO) or reduced graphene oxide (rGO) at different ratios to prevent aggregation of the MoSe 2 nanosheets and hence improve their electrocatalytic hydrogen evolution reaction performance. The prepared GO, rGO, and MoSe 2 nanosheets were characterized by X-ray powder diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and scanning electron microscopy. The electrocatalytic performance results showed that the pure MoSe 2 nanosheets exhibited a somewhat high Tafel slope of 80 mV/dec, whereas the MoSe 2-GO and MoSe 2-rGO composites showed lower Tafel slopes of 57 and 67 mV/dec at ratios of 6: 4 and 4: 6, respectively. We attribute the improved catalytic effects to the better contact and faster carrier transfer between the edge of MoSe 2 and the electrode due to the addition of GO or rGO. View Full-Text
The issues of global warming and fossil fuel shortage have increased the demand for clean and renewable energy. Many researchers are investigating strategies to produce hydrogen and reduce CO2 by using solar power. Two-dimensional (2D) materials, such as graphene, graphene derivatives, and transition metal dichalcogenides (TMDs), have been extensively used owing to their extraordinary electronic and optical properties. In this review, we investigate the recent developments in 2D materials for photocatalytic applications involving the hydrogen evolution reaction and CO2 reduction. The synthesis methods and the photocatalytic properties of TMDs and graphene-based 2D materials are thoroughly discussed. Moreover, a summary of the recently developed 2D nanostructures and devices for solar hydrogen production and CO2 reduction is presented, and it is revealed that the use of 2D catalyst materials …
In this paper, a facile method for synthesizing WS2 nanoflowers (NFs) and CdSe quantum dots (QDs) using hydrothermal and hot injection methods, are reported, respectively. Additionally, the photocatalytic activity of a CdSe QDs/WS2 NF nanocomposite is analyzed in a typical three‐electrode electrochemical cell. It is found that the CdSe QDs/WS2 NF hybrid exhibits a current density of −1.12 mA at 0 V and a Tafel slope of 82 mV dec−1, which are superior to the values of bare WS2 NFs (current density of −0.25 mA and Tafel slope of 150 mV dec−1). This improvement of photocatalytic performance is attributed to the wide range of light absorption for e−/h+ generation provided by the CdSe QDs, as well as the large surface area and numerous active sites for hydrogen production provided by WS2 NFs. Therefore, the CdSe QDs/WS2 NF hybrid structure is a promising candidate for highly effective and stable …
