Tianyu Lei

Self‐Powered, Flexible, and Solution‐Processable Perovskite Photodetector Based on Low‐Cost Carbon Cloth

Flexible perovskite photodetectors are usually constructed on indium-tin-oxide-coated polymer substrates, which are expensive, fragile, and not resistant to high temperature. Herein, for the first time, a high-performance flexible perovskite photodetector is fabricated based on low-cost carbon cloth via a facile solution processable strategy. In this device, perovskite microcrystal and Spiro-OMeTAD (hole transporting material) blended film act as active materials for light detection, and carbon cloth serves as both a flexible substrate and a conductive electrode. The as-fabricated photodetector shows a broad spectrum response from ultraviolet to near-infrared light, high responsivity, fast response speed, long-term stability, and self-powered capability. Flexible devices show negligible degradation after several tens of bending cycles and at the extremely bending angle of 180°. This work promises a new technique to construct flexible, high-performance photodetectors with low cost and self-powered capability.

TiO2 Feather Duster as Effective Polysulfides Restrictor for Enhanced Electrochemical Kinetics in Lithium–Sulfur Batteries

The rechargeable lithium-sulfur battery is recognized as a promising candidate for electrochemical energy storage system because of their exceptional advance in energy density. However, the fast capacity decay of sulfur cathode caused by polysulfide dissolution and low specific capacity caused by poor electrical conductivity still impede the further development of lithium-sulfur battery. To address above issues, this study reports the synthesis of feather duster-like TiO2 architecture by in situ growth of TiO2 nanowires on carbon cloth and further evaluates as sulfur host material. The strong chemical binding interaction between the polysulfides and TiO2 feather duster efficiently restrains the shuttle effect, leading to enhanced electrochemical kinetics. Besides, the in situ grown TiO2 NWs array also supply high surface for sulfur-loading and fast path for electron transfer and ion diffusion. As results, the novel CC/TiO2 /S composite cathode exhibits a high capacity of 608 mA h g-1 at 1.0 C after 700 cycles corresponding to capacity decay as low as 0.045% per cycle with excellent Coulombic efficiency higher than 99.5%.

Electronic and Optoelectronic Applications Based on 2D Novel Anisotropic Transition Metal Dichalcogenides

Abstract With the continuous exploration of 2D transition metal dichalcogenides (TMDs), novel high‐performance devices based on the remarkable electronic and optoelectronic natures of 2D TMDs are increasingly emerging. As fresh blood of 2D TMD family, anisotropic MTe2 and ReX2 (M = Mo, W, and X = S, Se) have drawn increasing attention owing to their low‐symmetry structures and charming properties of mechanics, electronics, and optoelectronics, which are suitable for the applications of field‐effect transistors (FETs), photodetectors, thermoelectric and piezoelectric applications, especially catering to anisotropic devices. Herein, a comprehensive review is introduced, concentrating on their recent progresses and various applications in recent years. First, the crystalline structure and the origin of the strong anisotropy characterized by various techniques are discussed. Specifically, the preparation of these 2D materials is presented and various growth methods are summarized. Then, high‐performance applications of these anisotropic TMDs, including FETs, photodetectors, and thermoelectric and piezoelectric applications are discussed. Finally, the conclusion and outlook of these applications are proposed.

A New Member of Electrocatalysts Based on Nickel Metaphosphate Nanocrystals for Efficient Water Oxidation

High-performance electrocatalysts are desired for electrochemical energy conversion, especially in the field of water splitting. Here, a new member of phosphate electrocatalysts, nickel metaphosphate (Ni2 P4 O12 ) nanocrystals, is reported, exhibiting low overpotential of 270 mV to generate the current density of 10 mA cm-2 and a superior catalytic durability of 100 h. It is worth noting that Ni2 P4 O12 electrocatalyst has remarkable oxygen evolution performance operating in basic media. Further experimental and theoretical analyses demonstrate that N dopant boosts the catalytic performance of Ni2 P4 O12 due to optimizing the surface electronic structure for better charge transfer and decreasing the adsorption energy for the oxygenic intermediates.

High-Performance SERS Substrate Based on Hierarchical 3D Cu Nanocrystals with Efficient Morphology Control

Cu nanocrystals of various shapes are synthesized via a universal, eco-friendly, and facile colloidal method on Al substrates using hexadecylamine (HDA) as a capping agent and glucose as a reductant. By tuning the concentration of the capping agent, hierarchical 3D Cu nanocrystals show pronounced surface-enhanced Raman scattering (SERS) through the concentrated hot spots at the sharp tips and gaps due to the unique 3D structure and the resulting plasmonic couplings. Intriguingly, 3D sword-shaped Cu crystals have the highest enhancement factor (EF) because of their relatively uniform size distribution and alignment. This work opens new pathways for efficiently realizing morphology control for Cu nanocrystals as highly efficient SERS platforms.

Atomic Interlamellar Ion Path in High Sulfur Content Lithium-Montmorillonite Host Enables High-Rate and Stable Lithium-Sulfur Battery

Fast lithium ion transport with a high current density is critical for thick sulfur cathodes, stemming mainly from the difficulties in creating effective lithium ion pathways in high sulfur content electrodes. To develop a high-rate cathode for lithium-sulfur (Li-S) batteries, extenuation of the lithium ion diffusion barrier in thick electrodes is potentially straightforward. Here, a phyllosilicate material with a large interlamellar distance is demonstrated in high-rate cathodes as high sulfur loading. The interlayer space (≈1.396 nm) incorporated into a low lithium ion diffusion barrier (0.155 eV) significantly facilitates lithium ion diffusion within the entire sulfur cathode, and gives rise to remarkable nearly sulfur loading-independent cell performances. When combined with 80% sulfur contents, the electrodes achieve a high capacity of 865 mAh g-1 at 1 mA cm-2 and a retention of 345 mAh g-1 at a high discharging/charging rate of 15 mA cm-2 , with a sulfur loading up to 4 mg. This strategy represents a major advance in high-rate Li-S batteries via the construction of fast ions transfer paths toward real-life applications, and contributes to the research community for the fundamental mechanism study of loading-independent electrode systems.

Ferromagnetic–Antiferromagnetic Coupling by Distortion of Fe/Mn Oxygen Octahedrons in (BiFeO3)m(La0.7Sr0.3MnO3)n Superlattices

Interface enhanced magnetism attracts much attention due to its potential use in exploring novel structure devices. Nevertheless, the magnetic behavior at interfaces has not been quantitatively determined. In this study, abnormal magnetic moment reduction is observed in La0.7 Sr0.3 MnO3 (LSMO)/BiFeO3 (BFO) superlattices, which is induced by ferromagnetic (FM)/antiferromagnetic (AFM) coupling in the interface. With reduced repetition of the superlattices unit cell [(LSMO)n /(BFO)n ]60/n (n = 1, 2, 5, 10) on a SrTiO3 substrate, magnetic moment reduction from 25.5 emu cc-1 ([(LSMO)10 /(BFO)10 ]6 ) to 1.5 emu cc-1 ([(LSMO)1 /(BFO)1 ]60 ) is obtained. Ab initio simulations show that due to the different magnetic domain formation energies, the magnetic moment orientation tends to be paramagnetic in the FM/AFM interface. The work focuses on the magnetic domain formation energy and provides a pathway to construct artificial heterostructures that can be an effective way to tune the magnetic moment orientation and control the magnetization of ultrathin films.