Minghui Shang

Superior thoroughly mesoporous ternary hybrid photocatalysts of TiO2/WO3/g-C3N4 nanofibers for visible-light-driven hydrogen evolution

A novel and highly efficient visible-light-driven photocatalyst with robust stability, made up of thoroughly mesoporous TiO2/WO3/g-C3N4 ternary hybrid nanofibers, has been fabricated through a foaming-assisted electrospinning process followed by a solution dipping process. These fibers, without the assistance of a noble metal, yielded a high visible-light-driven photocatalytic H2 release rate of ∼286.6 μmol h−1, which was 65 times greater than that displayed by the pure TiO2 counterparts.

Long-lived and Well-resolved Mn 2+ Ion Emissions in CuInS-ZnS Quantum Dots

CuInS2 (CIS) quantum dots (QDs) have tunable photoluminescence (PL) behaviors in the visible and near infrared spectral range with markedly lower toxicity than the cadmium-based counterparts, making them very promising applications in light emitting and solar harvesting. However, there still remain material- and fabrication- related obstacles in realizing the high-performance CIS-based QDs with well-resolved Mn2+ d-d emission, long emission lifetimes as well as high efficiencies. Here, we demonstrate the growth of high-quality Mn2+-doped CuInS-ZnS (CIS-ZnS) QDs based on a multi-step hot-injection strategy. The resultant QDs exhibit a well-resolved Mn2+ d-d emission with a high PL quantum yield (QY) up to 66% and an extremely long excited state lifetime up to ~3.78 ms, which is nearly two times longer than the longest one of “green” QDs ever reported. It is promising that the synthesized Mn2+-doped CIS-ZnS QDs might open new doors for their practical applications in bioimaging and opto/electronic devices.

Efficient Photocatalytic Activities of TiO2 Hollow Fibers with Mixed Phases and Mesoporous Walls.

Currently, Degussa P25, with the typical mixed phases of anatase and rutile TiO2, is widely applied as the commercial photocatalysts. However, there are still some of obstacles for the P25 nanoparticles with totally high photocatalytic activities, especially for the catalytic stability due to their inevitable aggregation of the nanoparticles when used as the photocatalysts. In the present work, we reported the exploration of a novel TiO2 photocatalyst, which could offer an ideal platform for synergetic combination of the mixed-phase composition, hollow architecture and mesoporous walls for the desired excellent photocatalytic efficiency and robust stability. The mesoporous TiO2 hollow nanofibers were fabricated via a facile single capillary electrospinning technique, in which the foaming agents were used for creating mesopores throughout the walls of the hollow fibers. The obtained hollow fibers exhibit a high purity and possess the mixed phases of 94.6% anatase and 5.4% rutile TiO2. As compared to P25, the as-fabricated mesoporous TiO2 hollow fibers exhibited much higher efficient photocatalytic activities and stabilities toward the hydrogen evolution with a rate of ~499.1 μmol g−1·h−1 and ~99.5% degradation Rhodamine B (RhB) in 60 min, suggesting their promising application in efficient photocatalysts.

Highly Efficient Photocatalytic Hydrogen Evolution in Ternary Hybrid TiO2/CuO/Cu Thoroughly Mesoporous Nanofibers

Development of novel hybrid photocatalysts with high efficiency and durability for photocatalytic hydrogen generation is highly desired but still remains a grand challenge currently. In the present work, we reported the exploration of ternary hybrid TiO2/CuO/Cu thoroughly mesoporous nanofibers via a foaming-assisted electrospinning technique. It is found that by adjusting the Cu contents in the solutions, the unitary (TiO2), binary (TiO2/CuO, TiO2/Cu), and ternary (TiO2/CuO/Cu) mesoporous products can be obtained, enabling the growth of TiO2/CuO/Cu ternary hybrids in a tailored manner. The photocatalytic behavior of the as-synthesized products as well as P25 was evaluated in terms of their hydrogen evolution efficiency for the photodecomposition water under Xe lamp irradiation. The results showed that the ternary TiO2/CuO/Cu thoroughly mesoporous nanofibers exhibit a robust stability and the most efficient photocatalytic H2 evolution with the highest release rate of ∼851.3 μmol g(-1) h(-1), which was profoundly enhanced for more than 3.5 times with respect to those of the pristine TiO2 counterparts and commercial P25, suggesting their promising applications in clean energy production.

Extremely Stable Current Emission of P-Doped SiC Flexible Field Emitters

Novel P‐doped SiC flexible field emitters are developed on carbon fabric substrates, having both low E to of 1.03–0.73 Vμm−1 up to high temperatures of 673 K, and extremely high current emission stability when subjected to different bending states, bending circle times as well as high temperatures (current emission fluctuations are typically in the range ±2.1%–3.4%).

Enhanced field emission of p-type 3C-SiC nanowires with B dopants and sharp corners

Field emission with a low turn-on field and high stability is very important and highly desired for the practical application of nanostructures in electron emitters. In the present study, we report the growth of p-type 3C-SiC nanowires with B dopants and sharp corners created via the catalyst-assisted pyrolysis of a polymeric precursor. The morphologies, structures and field emission (FE) properties of the resultant SiC nanowires were investigated. FE measurements suggest that the B-doped SiC nanowires have excellent FE performance with a low turn-on field of 1.35 V μm−1 and a high field enhancement factor of ∼4895. More importantly, the current emission fluctuation of B-doped nanowires with an applied field of 1.88 V μm−1 at 200 °C could be improved to ∼11% from ∼22% of the undoped counterparts, suggesting that the high-temperature FE stability of SiC nanowires could be significantly enhanced by the B dopants. The excellent FE performances could be attributed to the special p-type triangular prism-like nanostructures with B dopants and numerous sharp corners on the prism edges, which could reduce the effective work function and remarkably increase the emission site density.

High-performance solar-blind ultraviolet photodetector based on electrospun TiO2-ZnTiO3 heterojunction nanowires

High-performance solar-blind UV (ultraviolet) photodetectors (PDs) based on low-dimension semiconducting nanostructures with high sensitivity, excellent cycle stability, and the ability to operate in harsh environments are critical for solar observations, space communication, UV astronomy, and missile tracking. In this study, TiO2-ZnTiO3 heterojunction nanowire-based PDs are successfully developed and used to detect solar-blind UV light. A photoconductive analysis indicates that the fabricated PDs are sensitive to UV illumination, with high sensitivity, good stability, and high reproducibility. Further analysis indicates that the rich existence of grain boundaries within the TiO2-ZnTiO3 nanowire can greatly decrease the dark current and recombination of the electron-hole pairs and thereby significantly increase the device’s photosensitivity, spectra responsivity (1.1 × 106), and external quantum efficiency (4.3 × 108 %). Moreover, the PDs exhibit good photodetective performance with fast photoresponse and recovery and excellent thermal stability at temperatures as high as 175 °C. According to these results, TiO2-ZnTiO3 heterojunction nanowires exhibit great potential for applications in high-performance optical electronics and PDs, particularly next-generation photodetectors with the ability to operate in harsh environments.

Foaming-assisted electrospinning of large-pore mesoporous ZnO nanofibers with tailored structures and enhanced photocatalytic activity

1D large-pore mesoporous ZnO materials have attracted tremendous attention because of their outstanding properties and promising applications in a wide range of fields. In the present work, we report the fabrication of large-pore mesoporous ZnO nanofibers via an improved electrospinning strategy, namely, the foaming-assisted electrospinning technique, combined with subsequent calcination treatment. The as-fabricated large-pore mesoporous nanofibers were systematically characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer–Emmett–Teller (BET) specific surface area (SBET). The obtained products possess well-designed 1D mesoporous nanostructure with high purity and homogeneous large pore sizes. It is found that the content of the foaming agent within the solutions plays a crucial role in the formation of large-pore mesoporous ZnO nanofibers, enabling the growth of the fibers in a controlled manner. The resultant large-pore mesoporous nanofibers exhibit excellent photocatalytic activity and significant stability for hydrogen production compared to conventional solid nanofibers. The present work suggests a facile preparation of the large-pore mesoporous ZnO nanofibers, which may open new doors for their potential applications in photocatalysts.

Current emission from P-doped SiC nanowires with ultralow turn-on fields

In the present work, we reported the current emission from P-doped SiC nanowire field emitters, which were synthesized via catalyst-assisted pyrolysis of polysilazane precursors. Directed by F–N theory for enhanced field emission (FE) behaviors, the emitters were grown into nanostructures with two desired characteristics, namely with an ultrahigh aspect ratio as well as incorporated P dopants, which brought profound enhancements to the field enhancement factor (β) and turn-on field (Eto). The as-grown SiC nanowires (SiCNWs) exhibit an aspect ratio over 1500 with a uniform spatial distribution of P dopants. The FE measurements exhibit that the SiCNWs possessed a field enhancement factor up to 11657 and an ultralow Eto of 0.47 V μm−1, which was little achieved among the reported studies. The current emission fluctuations are ∼±4.0% over 5 h, suggesting their good electron emission stability. We mainly attributed the totally excellent FE performances to the ultra-high aspect ratio and the incorporated P dopants of the obtained SiCNWs, which could synergistically cause a significant increase of the field enhancement factor and a decrease of the work function.

Enhancing the Performance of Quantum Dot Light-Emitting Diodes Using Room-Temperature-Processed Ga-Doped ZnO Nanoparticles as the Electron Transport Layer

Colloidal ZnO nanoparticle (NP) films are recognized as efficient electron transport layers (ETLs) for quantum dot light-emitting diodes (QD-LEDs) with good stability and high efficiency. However, because of the inherently high work function of such films, spontaneous charge transfer occurs at the QD/ZnO interface in such a QD-LED, thus leading to reduced performance. Here, to improve the QD-LED performance, we prepared Ga-doped ZnO NPs with low work functions and tailored band structures via a room-temperature (RT) solution process without the use of bulky organic ligands. We found that the charge transfer at the interface between the CdSe/ZnS QDs and the doped ZnO NPs was significantly weakened because of the incorporated Ga dopants. Remarkably, the as-assembled QD-LEDs, with Ga-doped ZnO NPs as the ETLs, exhibited superior luminances of up to 44 000 cd/m2 and efficiencies of up to 15 cd/A, placing them among the most efficient red-light QD-LEDs ever reported. This discovery provides a new strategy for fabricating high-performance QD-LEDs by using RT-processed Ga-doped ZnO NPs as the ETLs, which could be generalized to improve the efficiency of other optoelectronic devices.