Metal/Semiconductor Hybrid Nanocrystals and Synergistic Photocatalysis Applications

This review focuses on recent research efforts to synthesize metal/semiconductor hybrid nanocrystals, understand and control the photocatalytic applications. First, we summarize the synthesis methods and recent presented metal/seminconductor morphologies, including heterodimer, core/shell, and yolk/shell etc. The metal clusters and nanocrystals deposition on semiconductor micro/nano substrates with well-defined crystal face exposure will be clarified into heterodimer part. The outline of this synthesis part will be the large lattice mismatch directed interface, contact and morphologies evolution. For detailed instructions on each synthesis, the readers are referred to the corresponding literature. Secondly, the recent upcoming photocatalysis applications and research progress of these hybrid nanocrystals will be reviewed, including the photocatalytic hydrogen evolution (water splitting), photo-reduction of CO2 and other newly emerging potential photosynthesis applications of metal/semiconductor hybrid nanocrystals. Finally, we summarize and outlook the future of this topic. From this review, we try to facilitate the understanding and further improvement of current and practical metal/semiconductor hybrid nanocrystals and photocatalysis applications

Dimethyl 3,3′-diphenyl-2,2′-[(S)-thio­phene-2,5-diylbis(carbonyl­aza­nedi­yl)]dipropano­ate tetra­hydro­furan monosolvate

The title compound, C26H26N2O6S·C4H8O, a solvated bis-amide derivative, is also a chiral amino acid ester with l-phenyl­alanine methyl ester groups as amine substituents. The thio­phene-2,5-dicarboxamide core approximates C 2 point symmetry. The tetra­hydro­furan solvent mol­ecule is linked to the main mol­ecule through an inter­molecular N—H⋯O hydrogen bond. The central ring makes dihedral angles of 90.0 (2) and 76.5 (2)° with the pendant rings

Rigid three-dimensional Ni3S4 nanosheet frames: Controlled synthesis and their enhanced electrochemical performance

Rigid three-dimensional (3D) NiS nanosheet frames assembled from ultrathin nanosheets are synthesized via a facile solvothermal method. Compared to flat NiS sheets, 3D NiS nanosheet frames have both a high free volume and high compressive strength. They can deliver a very high specific capacitance of 1213 F g with good rate performance. In addition, these 3D NiS nanosheet frames are stabilized by plastically deformed ridges. The stabilized nanosheet frames did not unfold or collapse during electrochemical tests, and thus showed enhanced cycling ability

Low-Light Image Enhancement with an Anti-Attention Block-Based Generative Adversarial Network

High-quality images are difficult to obtain in complex environments, such as underground or underwater. The low performance of images that are captured under low-light conditions significantly restricts the development of various engineering applications. However, existing algorithms exhibit color distortion or under/overexposure when addressing non-uniform illumination images. Furthermore, they introduce high-level noise when processing extremely dark images. In this paper, we propose a novel generative adversarial network (GAN) structure to generate high-quality enhanced images, which is called anti-attention block (AAB)-based generative adversarial networks (AABGAN). Specifically, we propose AAB to suppress undesired chromatic aberrations and establish a mapping relationship between different channels. The deep aggregation pyramid pooling module guides the network when combining multi-scale context information. Furthermore, we design a new multiple loss function to adjust images to the most suitable range for human vision. The results of extensive experiments show that our method outperforms state-of-the-art unsupervised image enhancement methods in terms of noise reduction and has a well-perceived result

Low-Light Image Enhancement with an Anti-Attention Block-Based Generative Adversarial Network

High-quality images are difficult to obtain in complex environments, such as underground or underwater. The low performance of images that are captured under low-light conditions significantly restricts the development of various engineering applications. However, existing algorithms exhibit color distortion or under/overexposure when addressing non-uniform illumination images. Furthermore, they introduce high-level noise when processing extremely dark images. In this paper, we propose a novel generative adversarial network (GAN) structure to generate high-quality enhanced images, which is called anti-attention block (AAB)-based generative adversarial networks (AABGAN). Specifically, we propose AAB to suppress undesired chromatic aberrations and establish a mapping relationship between different channels. The deep aggregation pyramid pooling module guides the network when combining multi-scale context information. Furthermore, we design a new multiple loss function to adjust images to the most suitable range for human vision. The results of extensive experiments show that our method outperforms state-of-the-art unsupervised image enhancement methods in terms of noise reduction and has a well-perceived result

Non-Coplanar Diphenyl Fluorene and Weakly Polarized Cyclohexyl Can Effectively Improve the Solubility and Reduce the Dielectric Constant of Poly (Aryl Ether Ketone) Resin

With the rapid development of high-frequency communication and large-scale integrated circuits, insulating dielectric materials require a low dielectric constant and dielectric loss. Poly (aryl ether ketone) resins (PAEK) have garnered considerable attention as an intriguing class of engineering thermoplastics possessing excellent chemical and thermal properties. However, the high permittivity of PAEK becomes an obstacle to its application in the field of high-frequency communication and large-scale integrated circuits. Therefore, reducing the dielectric constant and dielectric loss of PAEK while maintaining its excellent performance is critical to expanding the PAEK applications mentioned above. This study synthesized a series of poly (aryl ether ketone) resins that are low dielectric, highly thermally resistant, and soluble, containing cyclohexyl and diphenyl fluorene. The effects of cyclohexyl contents on the properties of a PAEK resin were studied systematically. The results showed that weakly-polarized cyclohexyl could reduce the molecular polarization of PAEK, resulting in low permittivity and high transmittance. The permittivity of PAEK is 2.95–3.26@10GHz, and the transmittance is 65–85%. In addition, the resin has excellent solubility and can be dissolved in NMP, DMF, DMAc, and other solvents at room temperature. Furthermore, cyclohexyl provided PAEK with excellent thermal properties, including a glass transition temperature of 239–245 °C and a 5% thermogravimetric temperature, under a nitrogen atmosphere of 469–534 °C. This makes it a promising candidate for use in high-frequency communications and large-scale integrated circuits

Cyclization mechanism and kinetics of poly(acrylonitrile-co-2-acrylamido-2-methylpropane sulfonic acid) copolymer investigated by FTIR spectroscopy

Cyclization reaction of poly(acrylonitrile-co-2-acrylamido-2-methylpropane sulfonic acid) [P(AN-co-AMPS)] copolymer during thermal oxidative stabilization (TOS) process was investigated by FTIR and two dimensional (2D) correlation analysis technique. The results showed the mechanism of cyclization reaction at different temperatures were varying. At 200 °C, the cyclization reactions generated by autocatalytic cyclization mechanism. While at higher temperatures, the cyclization reactions took place through ionic cyclization mechanism and free radical cyclization mechanism. The AMPS comonomer could reduce the heat release of cyclization reactions and improve the stability at 200 and 230 °C. At higher temperatures, the cyclization reactions were facilitated rapidly. However, the oxidation and degradation reactions were also intense, which will cause the molecular chain to break and defects in the final carbon fibers (CFs). This research has theoretical guiding significance for the optimization of heat treatment conditions for PAN copolymers used as CFs

HsGDY on Ni Foam for Loading MoS2/Ni3S2 to Enhance the Performance on Lithium–Sulfur Batteries

Lithium–sulfur batteries are considered important devices for the power of movable equipment, but there are still some challenges that limit their applications, such as how to obtain a cathode for high sulfide adsorption and rapid conversion. Here, a new strategy is proposed to enhance the performance of lithium–sulfur batteries by growing 3-dimensional hydrogen-substituted graphdiyne (HsGDY) layers on Ni foam via Glaser cross-coupling reaction to anchor MoS2/Ni3S2, enhancing the conductivity of host material of S. The results show that the 3-dimensional HsGDY framework enables the fast adsorption of lithium polysulfides and the Ni3S2/MoS2 performs as the reaction center with a low charge transfer resistance. The charge capacity of Ni@HsGDY/MoS2/Ni3S2 cell is up to 1,234.7 mAh·g−1 at the first circle, and the specific capacity keeps 486 mAh·g−1 after 500 cycles at a current density of 2 C. The incorporation of HsGDY into the cathode promotes the adsorption and the conversion of polysulfides, paving a path to obtain lithium–sulfur batteries with high energy density

Preparation, Stabilization and Carbonization of a Novel Polyacrylonitrile-Based Carbon Fiber Precursor

The quality of polyacrylonitrile (PAN) precursor has a great influence on the properties of the resultant carbon fibers. In this paper, a novel comonomer containing the sulfonic group, 2-acrtlamido-2-methylpropane acid (AMPS), was introduced to prepare P(AN-co-AMPS) copolymers using itaconic acid (IA) as the control. The nanofibers of PAN, P(AN-co-IA), and P(AN-co-AMPS) were prepared using the electrospinning method. The effect of AMPS comonomer on the carbon nanofibers was studied using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and Raman spectrum. The structural evolutions of PAN-based nanofibers were quantitatively tracked by FTIR and XRD during the thermal oxidative stabilization (TOS) process. The results suggested that P(AN-co-AMPS) nanofibers had the lower heat release rate (ΔH/ΔT = 26.9 J g−1 °C−1), the less activation energy of cyclization (Ea1 = 26.6 kcal/mol and Ea2 = 27.5 kcal/mol), and the higher extent of stabilization (Es and SI) during TOS process, which demonstrated that the AMPS comonomer improved the efficiency of the TOS process. The P(AN-co-AMPS) nanofibers had the better thermal stable structures. Moreover, the carbon nanofibers derived from P(AN-co-AMPS) precursor nanofibers had the better graphite-like structures (XG = 46.889). Therefore, the AMPS is a promising candidate comonomer to produce high performance carbon fibers