[en] Highlights: •An integration strategy was presented to construct Ni₃S₂ based hierarchical composite. •Nanowhisker Ni₃S₂ were densely integrated onto halloysite nanotubes. •The well-designed electrode exhibits remarkable capacitance and cycling stability. •This strategy provides good reference to electrode materials design for energy storage -- Abstract: Cost-effective and robust energy storage systems have attracted great attention for portable electronic devices. Three-dimensional electrodes can effectively enhance the charge transfer, increase the mechanical stability and thus improve the electrochemical performance upon continuous charge-discharge. The earth abundant halloysite nanotubes (HNTs) have shown immense potential in constructing nanoarchitectural composites. Here, we first demonstrate the development of hybrid composite of nickel sulfide (Ni₃S₂) and HNTs with glucose as binders for efficient energy storage in supercapacitor. The surface sulfhydrylation of HNTs and glucose-assisted hydrothermal reaction are crucial for the preparation of well-structured composite. Due to the synergistic effect between components, the Ni₃S₂/HNTs@HS composite electrode delivers a capacity of 450.4C g⁻¹ and high retention of 82.6% over 2000 cycles in three-electrode supercapacitors. Moreover, the Ni₃S₂/HNTs@HS//Whatman paper//Ni₃S₂/HNTs@HS two-electrode symmetric supercapacitor exhibits a maximum potential window of 1.3 V, with a capacity of 250C g⁻¹ and performance loss of only 18.2% over 2000 cycling at 1 A g⁻¹. A maximum energy density of 79.6 Wh kg⁻¹ is achieved at a power density of 1.03 kW kg⁻¹. Such excellent energy storage performance suggests the great potential of Ni₃S₂/HNTs@HS for high-efficiency energy storage systems.

[en] Highlights: In this paper, we demonstrate: • The click synthesis of a AC regioisomer cationic cyclodextrin (CD) as chiral selector. • The good enantioselectivities (chiral resolution over 5) for acidic racemates. • The strong chiral recognition of new CD by NMR study. • Baseline enantioseparation of some acidic racemates at CD of 0.5 mM. - Abstract: In this work, a novel methoxypropylamino β-cyclodextrin (β-CD) clicked AC regioisomer, 6"A-4-hydroxyethyl-1,2,3-triazolyl-6"C-3-methoxypropylamino β-cyclodextrin (HETz-MPrAMCD), was synthesized via nucleophilic addition and click chemistry. The chiral separation ability of this AC regioisomer cationic CD was evaluated toward 7 ampholytic and 13 acidic racemates by capillary electrophoresis. Dependence of enantioselectivity and resolution on buffer pH (5.5–8.0) and chiral selector concentration (0.5–7.5 mM) was investigated. Enantioselectivities (α ≥ 1.05) could be achieved for most analytes under optimal conditions except dansyl-DL-noreleucine and dansyl-DL-serine. The highest resolutions for 2-chloromandelic acid p-hydroxymandelic acid were 15.6 and 9.7 respectively. The inclusion complexation between HETz-MPrAMCD and each 3-phenyllactic acid enantiomer was also revealed with nuclear magnetic resonance study

[en] (La_0.7Sr_0.3MnO₃)_n(BiFeO₃)_n multilayered thin films were deposited on (0 0 1) SrTiO₃ substrates by using the RF magnetron sputtering method, and their conduction mechanisms in the temperature range between 150 K and 300 K were investigated using several common dielectric conduction models. The results indicate the current-voltage characterization of the as-fabricated thin films obey Ohm's law at 300 K, but the space-charge-limited conduction mechanism becomes dominant in the as-fabricated thin films as the temperature is decreased.

[en] Highlights: • Interfacial engineering on Co-metal organic framework generates Co₃O₄ nanosheets. • Co₃O₄ nanosheets were stabilized on carbon cloth by hydrophilic carbon coating. • Abundant oxygen vacancies were introduced into Co₃O₄ nanosheets. • v-Co₃O₄/CC composite exhibits high specific capacitance (920 F g⁻¹ at 1 A g⁻¹) and excellent stability. • Asymmetric supercapacitor shows a maximum volumetric energy density of 0.74 mWh cm⁻³ at ap ower density of 14.70 mW cm⁻³. -- Abstract: Co₃O₄ is a promising pseudocapacitive material with a high theoretical capacity. We demonstrate herein a facile interfacial engineering toward Co-metal organic frameworks (Co-MOFs) derived Co₃O₄ nanosheets for improving the overall capacitive performance. Firstly, a thin hydrophilic carbon layer was coated onto carbon cloth (CC) to stablize the interfacial coordination effect between Co₃O₄ and carbon fibres. Secondly, oxygen vacancies by reducing Co₃O₄ was introduced to improve the electron and ions transfer on the interface between Co₃O₄ and electrolyte. The unique Co₃O₄ structure and composition endow the optimal v-Co₃O₄/CC composite with significantly improved specific capacity (414 C g⁻¹ at 1 A g⁻¹) and excellent stability (0.00174% capacity loss per cycle for 15000 cycles). Asymmetric supercapacitor by assembling v-Co₃O₄/CC composite as positive electrode with the same MOF derived carbon nanosheets as negative electrode demonstrates a high volumetric and gravimetric energy density of 0.74 mWh cm⁻³ (14.7 mW cm⁻³) and 45.3 Wh kg⁻¹ (915 W kg⁻¹), respectively. This work might provide a simple but efficient approach for boosting the pseudocapacitive performance of transition metal oxides.

[en] High quality epitaxial single phase (Ga_0.96Mn_0.04)₂O₃ and Ga₂O₃ thin films have been prepared on sapphire substrates by using laser molecular beam epitaxy (L-MBE). X-ray diffraction results indicate that the thin films have the monoclinic structure with a $\left(\stackrel{¯<!--\; ??\; -->}{2}01\right)$ preferable orientation. Room temperature (RT) ferromagnetism appears and the magnetic properties of β-(Ga_0.96Mn_0.04)₂O₃ thin film are enhanced compared with our previous works. Experiments as well as the first principle method are used to explain the role of Mn dopant on the structure and magnetic properties of the thin films. The ferromagnetic properties are explained based on the concentration of transition element and the defects in the thin films. (paper)

[en] Realizing manipulation of the photoelectric properties of wide bandgap semiconductors is a main challenge for successful next-generation functional optoelectronics. As an intriguing wide bandgap semiconductor, β-Ga₂O₃ (e.g. ∼4.9 eV) is emerging as a promising candidate for photodetectors operating in the solar-blind region. Here, we show that by selecting substrates with different symmetries and lattice parameters (i.e. (100) MgO, (100) MgAl₂O₄ and (0001) α-Al₂O₃), epitaxial β-Ga₂O₃ films with (100)-or $\left(\stackrel{¯<!--\; ??\; -->}{2}01\right)$-orientation could be fabricated. We found that the photoresponse characteristics are strongly correlated with the lattice mismatch and film orientation. In particular, (100)-oriented β-Ga₂O₃ film grown on MgO substrate with smaller lattice mismatch exhibited a 254 nm responsivity of 0.1 A · W⁻¹ and detectivity of 4.3 × 10¹² Jones, which are approximately an order of magnitude higher than that of the $\left(\stackrel{¯<!--\; ??\; -->}{2}01\right)$-oriented β-Ga₂O₃ film. Our work may provide a strategy to develop further high performance solar-blind photodetectors. (letter)

[en] Highlights: • Tubular hierarchical core-sheath NiS₂@Ni-Mn-O is achieved through HNTs-assisted hydrothermal reaction and sulfidation. • HNTs control the morphology of hybrids but also promote the charge and electrolyte transfer. • NiS₂@Ni-Mn-O/HNT symmetric SCs exhibit a highest 164.2 Wh kg⁻¹ energy density and 15.1 kW kg⁻¹ power density. The exploitation of electrode materials is extremely important for electrochemical energy storage systems with high energy and power densities as well as long lifespan. Herein, a facile halloysite nanotubes (HNTs) assisting deposition method is developed to prepare nickel disulfide interconnected nanosheet arrays on nickel manganese oxides (Ni-Mn-O) as electrodes for battery-type supercapacitors, resulting in exceptional energy storage performance. Taking advantage of the unique tubular architecture of hollow HNTs, gradient deposition of NiS₂ and Ni-Mn-O nanosheets on HNTs are realized with two-step in-situ hydrothermal reaction and sulfidation. HNTs not only favor the formation of NiS₂ during sulfidation but also offer good porosity for electrochemical energy storage. In solution state, the hybrid electrode exhibits a high capacity (1144.7C g⁻¹ at 1 A g⁻¹ and 597.5C g⁻¹ at 20 A g⁻¹) with excellent cyclic stability (92.6% after 2000 cycles). Solid-state symmetric supercapacitors fabricated with NiS₂@Ni-Mn-O/HNT hybrid demonstrate outstanding electrochemical performance for portable energy storage application. Our symmetric supercapacitors show a highest energy density of 164.2 Wh kg⁻¹ at a power density of 1.3 kW kg⁻¹. The energy density remains as high as 28 Wh kg⁻¹ even at the highest power density of 15.1 kW kg⁻¹ with good long-term cycling stability (90.5% after 2000 cycles).

[en] Flexible photodetectors (PDs) have received enormous interest owing to their potential applications in portable information technology and modern wearable optoelectronic devices. Herein, flexible solar-blind PDs based on amorphous Ga₂O₃ films fabricated on polyethylene naphthalate substrates at room temperature are demonstrated. The PD yields a responsivity up to 3.7 mA W⁻¹, a fast response speed of 80 ms, a large detectivity of 1.14 × 10¹² Jones, a high ultraviolet/visible rejection ratio of 6.1 × 10³, and an ultra-high photo-to-dark current ratio over 10⁵ at 10 V, which is comparable to the performance of a device on a rigid substrate. Moreover, the device exhibits no obvious performance degradation even after mechanical bending over 10³ cycles, indicating an excellent stability. Our results pave the route for the realization of high-performance solar-blind optoelectronics with a flexible substrate. (paper)

[en] Two SiO₂/Si interface structures, which are described by the double bonded model (DBM) and the bridge oxygen model (BOM), have been theoretically studied via first-principle calculations. First-principle simulations demonstrate that the width of the transition region for the interface structure described by DBM is larger than that for the interface structure described by BOM. Such a difference will result in a difference in the gate leakage current. Tunneling current calculation demonstrates that the SiO₂/Si interface structure described by DBM leads to a larger gate leakage current. (semiconductor physics)

[en] A laser synthetic wavelength interferometer that uses a large synthetic wavelength to subdivide fringes formed by a small single wavelength is described. This study emphasizes the interference signal processing for the interferometer to realize precision measurement. A novel fringe counting method of correcting the integer number of the interference fringe according to the displacement which corresponds to the fraction number is proposed. Through this method, the integer fringe counting error can be eliminated. The realization of the method is designed in detail. The experimental setup was constructed and the displacement experiment was performed in the range of 15 µm with 1 µm increment. The experimental results show that the average error is −2.64 nm and the standard deviation is 0.47 nm. This demonstrates the feasibility of the signal processing method for the laser synthetic wavelength interferometer