Showing papers by "Tao Tao published in 2020"

Engineering pristine 2D metal–organic framework nanosheets for electrocatalysis

Abstract: Due to their appealing properties such as abundant number of coordinatively unsaturated atoms, enhanced conductivity, high porosity, large surface area and tunable structure, 2D metal–organic framework (MOF) nanosheets have stimulated extensive research interest in the field of electrocatalysis. During the past several years, significant advances have been made in the direct applications of pristine 2D MOF nanosheets as efficient electrocatalysts. This review first discusses the synthetic strategies of MOF nanosheets. Then recent progress on pristine MOF nanosheets for electrocatalytic reactions, including the oxygen evolution reaction (OER), the oxygen reduction reaction (ORR), the hydrogen evolution reaction (HER), the carbon dioxide reduction reaction (CRR) and the urea oxidation reaction (UOR) is summarized. In particular, engineering electronic structures of pristine MOF nanosheets to favor efficient electrocatalytic processes are discussed. Despite the encouraging accomplishments achieved, more engineered pristine MOF nanosheets with enhanced electrocatalytic performance are still needed. Therefore, bottlenecks faced by current pristine MOF nanosheets for electrocatalysis and potential solutions to these problems are finally proposed to promote further development in this research field.

3D global aromaticity in a fully conjugated diradicaloid cage at different oxidation states.

Abstract: Aromaticity is a vital concept that governs the electronic properties of π-conjugated organic molecules and has long been restricted to 2D systems. The aromaticity in 3D π-conjugated molecules has been rarely studied. Here we report a fully conjugated diradicaloid molecular cage and its global aromaticity at different oxidation states. The neutral compound has an open-shell singlet ground state with a dominant 38π monocyclic conjugation pathway and follows the [4n + 2] Huckel aromaticity rule; the dication has a triplet ground state with a dominant 36π monocyclic conjugation pathway and satisfies [4n] Baird aromaticity; the tetracation is an open-shell singlet with 52 π-electrons that are delocalized along the 3D rigid framework, showing 3D global antiaromaticity; and the hexacation possesses D3 symmetry with 50 globally delocalized π-electrons, showing [6n + 2] 3D global aromaticity. Different types of aromaticity were therefore accessed in one molecular cage platform, depending on the symmetry, number of π-electrons and spin state. A conjugated diradicaloid cage has been synthesized and its aromaticity was investigated. The neutral compound and the dication have dominant monocyclic conjugation pathways and both are aromatic (the former following Huckel’s rule and the latter Baird’s rule). The tetracation ([6n + 4] π-electrons) exhibits global 3D antiaromaticity whereas the hexacation ([6n + 2] π-electrons) exhibits global 3D aromaticity and has high D3 symmetry.

Solar-blind ultraviolet photodetector based on vertically aligned single-crystalline β-Ga2O3 nanowire arrays

Abstract: Abstract Vertically aligned nanowire arrays, with high surface-to-volume ratio and efficient light-trapping absorption, have attracted much attention for photoelectric devices. In this paper, vertical β-Ga2O3 nanowire arrays with an average diameter/height of 110/450 nm have been fabricated by the inductively coupled plasma etching technique. Then a metal-semiconductor-metal structured solar-blind photodetector (PD) has been fabricated by depositing interdigital Ti/Au electrodes on the nanowire arrays. The fabricated β-Ga2O3 nanowire PD exhibits ∼10 times higher photocurrent and responsivity than the corresponding film PD. Moreover, it also possesses a high photocurrent to dark current ratio (Ilight/Idark) of ∼104 and a ultraviolet/visible rejection ratio (R260 nm/R400 nm) of 3.5 × 103 along with millisecond-level photoresponse times.

Strontium Chloride-Passivated Perovskite Thin Films for Efficient Solar Cells with Power Conversion Efficiency over 21% and Superior Stability

Abstract: Industrialization of perovskite solar cells is constrained by adverse stability in the air. Herein, we report effective strontium chloride (SrCl2) passivation upon HC(NH2)2–CH3NH3 (FA–MA)-based perovskite thin films for the suppression of nonradiative recombination. Moreover, the recombination dynamics, crystallinity, carrier transport, morphology, and the elemental stoichiometry of this film were systematically studied. By optimizing the concentration of SrCl2, the corresponding devices exhibited an increased open-circuit voltage (1.00 V vs 1.09 V), consistent with the enhanced photoluminescence lifetime. The champion passivated device showed an ascendant power conversion efficiency (PCE) about 21.11%, with over 90% retention of the primal PCE in dry air after 1000 h of aging with 20–30% humidity. A superior stability and an accelerated electron/hole-extraction ability were further observed by time-resolved photoluminescence spectroscopy.

Fabrication of MnOx-CeO2/cordierite catalysts doped with FeOx and CuO for preferable catalytic oxidation of chlorobenzene.

Abstract: A series of MnOx-CeO2 catalysts with MOx doping (M = Cu, Fe, Co and La) supported on cordierite were synthesized by the citric acid complex method, showing preferable catalytic oxidation of chlorob...

Electron-Beam-Driven III-Nitride Plasmonic Nanolasers in the Deep-UV and Visible Region.

Abstract: Plasmonic nanolasers based on wide bandgap semiconductors are presently attracting immense research interests due to the breaking in light diffraction limit and subwavelength mode operation with fast dynamics. However, these plasmonic nanolasers have so far been mostly realized in the visible light ranges, or most are still under optical excitation pumping. In this work, III-nitride-based plasmonic nanolasers emitting from the green to the deep-ultraviolet (UV) region by energetic electron beam injection are reported, and a threshold as low as 8 kW cm-2 is achieved. A fast decay time as short as 123 ps is collected, indicating a strong coupling between excitons and surface plasmon. Both the spatial and temporal coherences are observed, which provide a solid evidence for exciton-plasmon coupled polariton lasing. Consequently, the achievements in III-nitride-based plasmonic nanolaser devices represent a significant step toward practical applications for biological technology, computing systems, and on-chip optical communication.

High-Performance Semi-Polar InGaN/GaN Green Micro Light-Emitting Diodes

Abstract: Semi-polar micro-LEDs have gain increasing interests due to the advantages of polarization control and quantum efficiency improvement. In this work, a novel semi-polar (20–21)-plane micro-LEDs array has been designed and manufactured. In comparison with c-plane micro-LEDs, semi-polar micro-LEDs indicate better electrical and optical performance. The relative EQE of semi-polar micro-LEDs remains at 62% under the injected current density of 775.6 A/cm2, which indicates a reduced efficiency droop due to less polarization in MQWs. It has been further proved by a significant reduction of 55% in emission peak blue-shift under the injected current density from 11.1 A/cm2 to 775.6 A/cm2. In addition, the carrier recombination dynamics and spatial light distribution of semi-polar micro-LEDs with different pixel sizes have been studied. Fast recombination lifetime in smaller size semi-polar micro-LEDs indicates a promising way to be used as a high modulation bandwidth light source. Stable and uniform light distribution in a wider range of spatial azimuths further supports for the semi-polar micro-LEDs as a strong candidate for the applications of high-resolution display and high-speed visible light communication.

Differences of Characteristics and Performance with Bi3+ and Bi2O3 Doping Over TiO2 for Photocatalytic Oxidation Under Visible Light

Abstract: Bi-doped TiO2 photocatalysts were synthesized by sol with a high-pressure hydrothermal method and developed for the photocatalytic degradation of formaldehyde under the visible light irradiation and ambient temperature. According to characterization, some Bi-doped TiO2 can be transformed into the distinctive crystals phase of Bi4Ti3O12, which was crucial for improving activity. The excess Bi2O3 doping into TiO2, such as Bi2O3–N/TiO2 and Bi2O3–C/TiO2, generated a mixed oxides with Bi2O3 and Bi4Ti3O12, was not beneficial to increase the activity of HCHO oxidation, whereas Bi3+/TiO2 composed of TiO2 and Bi4Ti3O12 displayed a higher activity with good stability. It is noteworthy that Bi3+/TiO2 didn’t show the lowest binding energy. However, it exhibited a lower PL intensity, higher adsorption, and activity due to the uniform particulates, high surface areas, and the strong interaction between TiO2 and Bi4Ti3O12, attributing to create superoxide radical anion (.O2−) and hydroxyl radical (.OH). The present results of Bi3+/TiO2 indicated that HCHO could be effectively oxidized from 1.094 to 0.058 mg/m3 (94.7%) under visible light irradiation within 36 h. The current research made effort to draw out the existing state of Bi, which can be better, Bi3+ or Bi2O3, doped in the TiO2.

Micro-LED array device based on III-group nitride semiconductor and preparation method of Micro-LED array device

Abstract: The invention discloses a Micro-LED (Light Emitting Diode) array device based on a III-group nitride semiconductor. Etching is performed to form an array fan-shaped mesa structure penetrating througha p-type GaN layer, a quantum well active layer and an n-type GaN layer, a p-type array electrode is evaporated on the p-type GaN layer of the fan-shaped array, and an n-type array electrode is evaporated on the n-type GaN layer, and the n-type array electrode forms a retaining wall to isolate the fan-shaped mesas from one another. The invention also discloses a preparation method thereof. The retaining walls made of the n-type electrodes are additionally arranged between the light-emitting units of the Micro-LED fan-shaped mesa array, the width of the retaining walls is only 6-10 microns, theproblem of mutual crosstalk between the light-emitting units of the device is effectively solved on the premise that the size of the device is not remarkably increased, and independent control is achieved; and n-type electrode metal is used as a retaining wall, and a p-type electrode with a reticular structure is adopted, so that the current expansion range is increased, and the luminous efficiency is effectively improved.