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As a very important component of NIR spectroscopy, the enhancement of luminescent efficiency and the broadening of bandwidth for NIR light sources are still considered to be a challenge. Hereon, a novel Cr3+-doped MgO-Al 2 O 3 -SiO 2 multi-phase glass-ceramics was successfully constructed. Upon excitation of 400 nm, the glass-ceramics presented an ultra-broadband NIR emission peaking at ∼910 nm with full width at half maximum of >270 nm, and the internal/external quantum efficiency of 60.4 %/28.8 %. The integrated emission intensity remained at ∼86.6 %/80.9 % at 100 ℃/150 ℃ compared to the intensity at room temperature. Furthermore, a NIR device was made by encapsulating the glass-ceramics on 405 nm LED, which presented a NIR output power and photoelectric conversion efficiency of 322 mW/1117 mW and 2.72 %/2.39 % at the driven current of 100 mA/320 mA, respectively. This work realized simultaneous adjustment of luminescent efficiency and bandwidth by selective enrichment of Cr3+ ions into different crystal phases, which provides an effective strategy for improving the luminescent efficiency and bandwidth of NIR glass-ceramics. • A novel Cr3+-doped NIR glass-ceramics with multi-phase was successfully prepared. • The controllable NIR luminescence was achieved by selective enrichment of Cr3+ ions. • The glass-ceramics presented an ultra-broadband NIR emission and a FWHM of >270 nm. • The multi-phase glass-ceramics have a high IQE and EQE of 60.4 % and 28.8 %. • The work provides a roadmap for preparing high-performance NIR-emitting materials. [ABSTRACT FROM AUTHOR]

Photoelectrochemical sensing is a promising solution for health monitoring and food safety guarantee, and developing novel strategies for the facile preparation of advanced photoelectrochemical sensors is challenging. In this work, we report a novel strategy for preparing TiO 2 nanofibers threaded ZnO heterostructures and the selective photoelectrochemical detection of lactic acid. Cascade electrospinning and hot-pressing technologies were employed to prepare TiO 2 nanofibers threaded ZIF-8 precursor, and subsequent pyrolysis of ZIF-8 nanocrystals afforded beads-on-a-string heterostructures of TiO 2 @ZnO. The bead-like TiO 2 @ZnO heterostructures exhibit significantly enhanced charge transfer activity, photocurrent density and the smallest overpotential compared against that of ZnO and TiO 2. The resultant photoelectrochemical sensors demonstrate a low detection limit of 0.031 μM, a high sensitivity of 29.18 μA mM−1, a wide linear range between 0.1 and 1.0 mM, and excellent reproducibility. Furthermore, GC-MS and in situ FTIR studies confirm the mechanistic pathway of photoelectrochemical oxidation. This work provides a facile strategy for developing MOFs derived heterostructures, and advances in various high performance photoelectrochemical applications could be envisioned. [Display omitted] • Beads-on-a-string heterostructures of 1D TiO2@ZnO were fabricated. • Facile strategy of cascade hot-pressing ZIF-8 onto electrospun TiO2 was designed. • PEC detection of lactic acid was achieved with excellent selectivity and sensitivity. • Sensing mechanism was revealed by GC-MS and in situ DRIFTS studies. [ABSTRACT FROM AUTHOR]

First-principles calculations were conducted to examine the properties of complex pyrochlore oxides, using the Y 2 B 2 O 7 pyrochlore oxides (B Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Tc, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt) as a representative group. Hubbard U correction was involved in the calculations and a linear response approach was employed to determine the U values of the d -orbitals of the transition-metal elements. The application of U correction was demonstrated to notably improve prediction of structural properties (e.g., lattice parameter), electronic properties (e.g., bandgap and magnetic moment) and phonon frequencies of the pyrochlore oxides. The present study confirms the necessity of U correction in first-principles studies of pyrochlore oxides and provides essential data for future computational investigation of complex oxide systems. [ABSTRACT FROM AUTHOR]

In this paper, we report a facile method to prepare lanthanide-doped Na 3 ZrF 7 upconversion nanoparticles. By using this technique, monodisperse lanthanide-doped Na 3 ZrF 7 nanoparticles of approximately 10 nm in diameter could be synthesized at 260 °C. The Na 3 ZrF 7 :Yb 3+ 20%, Er 3+ 2%, and Na 3 ZrF 7 :Yb 3+ 20%, Tm 3+ 1% nanoparticles exhibited almost pure red and near-infrared emissions, respectively; however, the Na 3 ZrF 7 :Yb 3+ 20%, Ho 3+ 2% nanoparticles exhibited a multiband emission. The special emission output was caused by the cross relaxation of the activator ions, as a rare-earth ion (RE 3+ ) cluster was formed, shortening the distance between the RE 3+ ions. The emission output of the Na 3 ZrF 7 :Yb 3+ 20%, Er 3+ 2% nanoparticles was significantly influenced by the NaOH dosage. The Na 3 ZrF 7 :Yb 3+ 20%, Er 3+ 2% nanoparticles synthesized with a different NaOH dosage of 2.5 mmol showed the most intense total emission intensity among all samples. However, the red/green emission ratio was gradually enhanced as the NaOH dosage increased. [ABSTRACT FROM AUTHOR]

• CoSe 2 @NiSe 2 nanoflowers are synthesized via microwave method. • CoSe 2 @NiSe 2 electrode exhibits high capacitance value of 1434 F g−1 at 1 A g−1. • Good cycling stability of 87.5% retention after 20,000 cycles. [Display omitted] The work reports the fabrication of CoSe 2 @NiSe 2 nanoflowers on nickel foam substrates via one-step microwave method, in which the Ni foam serves as a skeleton and a nickel source. The as-prepared CoSe 2 @NiSe 2 nanoflowers display high capacitance value of 1434 F g−1 at the current density of 1 A g−1 and excellent cycling performance of 87.5% retention after 20,000 cycles at 10 A g−1. In addition, the supercapacitor device using CoSe 2 @NiSe 2 nanoflowers as the positive electrode and activated carbon (AC) as the negative electrode not only can exhibit wide voltage window of 1.6 V, but also deliver a maximum high energy density of 20.4 Wh Kg−1 at power density of 798 W Kg−1 and 86.6% of capacity retention after 20,000 cycles. [ABSTRACT FROM AUTHOR]

Despite excellent optoelectronic properties, the practical applications of halide perovskite nanocrystals (NCs) have been restricted by their intrinsic instability. In this study, heterostructured CsPbBr 3 /Cs 4 PbBr 6 @PbS NCs were successfully synthesized using a simple solvothermal method. CsPbBr 3 /Cs 4 PbBr 6 @PbS NCs exhibited strong fluorescence in visible and near infrared (NIR) region under excitation at 365 nm. Remarkably, the CsPbBr 3 /Cs 4 PbBr 6 @PbS NCs showed improved excellent thermal and humidity stabilities compared with CsPbBr 3 NCs. The incorporation of PbS shell could passivate the surface of CsPbBr 3 /Cs 4 PbBr 6 NCs, leading them to exhibit fluorescence at higher temperatures compared with CsPbBr 3 NCs, their fluorescence was quenched completely until the temperature was close to 200 °C while the fluorescence of CsPbBr 3 NCs disappeared at ∼100 °C. In addition, the incorporation of PbS shell also limit the etch effect of CsPbBr 3 /Cs 4 PbBr 6 NCs by water molecules, rendering them to retain the fluorescence after several months of exposure to air. These findings demonstrate a simple yet effective approach to improving the stability of perovskite NCs, providing new possibilities for their utilization in various optoelectronic devices. • The heterostructured CsPbBr 3 /Cs 4 PbBr 6 @PbS NCs were successfully synthesized. • CsPbBr 3 /Cs 4 PbBr 6 @PbS NCs exhibited strong dual-fluorescence in visible and near infrared (NIR) region. • The thermal and humidity stabilities of CsPbBr 3 /Cs 4 PbBr 6 @PbS NCs were enhanced significantly. • The CsPbBr 3 @Cs 4 PbBr 6 @PbS NCs retained their fluorescence after several months of exposure to air. [ABSTRACT FROM AUTHOR]

Abstract A novel ternary nanohybrid comprising Ag nanoparticles anchored on black phosphorus nanosheets (BPNS) supported on the surface of graphene oxide (GO) has been synthesized for the first time. UV–Vis spectra and X-ray photoelectron spectroscopy results revealed that BPNS with highly active P atoms on its surface served as a strong reductant to reduce Ag precursor and the emerging Ag atoms were consequently deposited on its surface. The Ag-BPNS/GO nanohybrid showed excellent photocatalytic activity towards the degradation of methylene blue under solar light irradiation. Broad spectrum response of BPNS, effective trapping of the electrons of Ag nanoparticles and high stability of Ag-BPNS on GO surface contributed the enhanced photocatalytic performance. A plausible mechanism has been proposed to explain the enhanced photocatalytic performance of the Ag-BPNS/GO nanohybrid. Graphical abstract Image 1 Highlights • Ag-BPNS/GO was successfully synthesized for the first time. • BPNS reduced Ag precursor and Ag atoms were deposited on its surface. • Ag-BPNS/GO showed excellent activity in methylene blue degradation. • Broad spectrum response and high dispersion contributed the excellent activity. [ABSTRACT FROM AUTHOR]

A combined buffer layer growth process was developed to grow crack-free GaN layers on 8-inch Si(111) wafers and so light-emitting diodes (LEDs). The combined buffer layer consisted of 2 nm-thick low-temperature (LT, 850 °C)-AlN, 8 nm-thick graded-temperature AlN, and 200 nm-thick high-temperature (HT, 1100 °C)-AlN layers. The X-ray diffraction (XRD) results showed that the LT-HT-AlN buffer layer exhibited better crystal quality than the HT-AlN buffer layer. The atomic force microscopy (AFM) images revealed that compared to the LT-HT-AlN buffer layer, the HT-AlN buffer layer had a rough surface with numerous bright spots, which correspond to N-polar AlN hillocks. Scanning electron microscopy (SEM) results showed many pits in the HT-AlN buffer layer. Transmission electron microscopy (TEM) results showed that the HT-AlN buffer layer contained about 1.3 nm-thick amorphous Si x N y layer at the interface, while the LT-HT-AlN buffer layer showed a relatively smooth interface. It was further shown that using the LT-HT-AlN buffer layer, high-quality crack-free n -GaN layers (2.5 μm-thick) were grown on the 8-inch Si(111) substrate, which was confirmed by the XRD and cathodoluminescence results. Subsequently, packaged vertical LEDs (chip size: 1400 × 1400 μm 2 ) grown on the LT-HT-AlN buffer layers showed higher light output power and chip yield than LEDs with the HT-AlN buffer layer. [ABSTRACT FROM AUTHOR]

In this work, a single-step and low-cost synthesis of all-inorganic cesium lead halide perovskite nanocrystals was developed. PbX 2 and Cs 2 CO 3 were added to a mixture containing 1-octadecene (ODE), oleic acid (OA) and oleylamine (OLA), and heated at 80–100 °C for 15–30 min in air. The resultant high-quality cube-like CsPbX 3 nanocrystals are monodisperse with dimensions of 7–15 nm, and display strong photoluminescence (PL) with a narrow, tuneable emission band of 14–43 nm and a high quantum yield (∼90%). The mechanisms of nucleation and growth were investigated by testing the effects of temperature and surface ligands (OA/OLA) on the crystal morphology and PL intensity. The high quality of the CsPbX 3 nanocrystals was further confirmed by efficient upconversion PL with high energy gain, observed here for the first time for colloidal CsPb(Br/I) 3 nanocrystals, with an energy gain higher than 430 meV that was mainly attributed to anti-stokes generation rather than the multiphoton effect. [ABSTRACT FROM AUTHOR]

The importance of ZT in thermoelectric (TE) materials is critical for green power generation and cooling applications. Therefore, tremendous efforts were underway to improve ZT, in which we proposed a layer structured approach by successively arranging of coarse Bi 0.5 Sb 1.5 Te 3 (BST) and fine BST/0.07Cu microstructure materials and investigated their transportation mechanism. The dual bulk microstructure was well-bonded and confirmed by analyzing the microstructure through scanning electron microscope (SEM), electron backscatter diffraction analysis (EBSD) and simulated the electrical potential and temperature distribution during spark plasma sintering with COMSOL software. The results indicate that the highest power factor of 3.8 mW/m-K2 was attained in the layer structured sample, which is significantly higher than other samples due to its synergistically optimized electrical conductivity and Seebeck coefficient. Through the varied microstructure, the κ was decreased at 400 K and consequently the ZT was improved to 1.25 at 400 K for the layer structure samples. Therefore, it is suggested that layered arrangement of different microstructure material could improve the thermoelectric properties of materials. [Display omitted] • Novel fabrication of hierarchical structured material with successive arrangement of two different microstructures. • Successful consolidation of well-bonded hierarchical material and confirming by simulating results from COMSOL software. • Highest power factor of 3.8 * 10−3 W/m-K2 obtained by transportation of charge carriers through two different energy levels. • Hierarchical structured sample show highest figure of merit of 1.25 at 400 K which is highest among all reported samples. [ABSTRACT FROM AUTHOR]

In this work, self-supported NiTe nanosheets were prepared via one-step microwave method. XRD and XPS spectroscopy showed the successful synthesis of NiTe material in the hexagonal crystal system. SEM and EDS were used to identify the microscopic morphology and composition of NiTe on nickel foam (NF). The electrode demonstrated specific capacitance (Cs) of 808.9 F g−1 and ultra-long cycle life of 60,000 cycles. In addition, a solid-state asymmetric supercapacitor consisted of NiTe@NF electrode as cathode material and demonstrated the largest energy density and power density of 94.4 μWh cm−2 and 7801.8 μW cm−2, respectively, and the specific capacitance remained 83.3% after 20,000 cycles. Moreover, the as-obtained NiTe@NF catalyst also displayed an excellent catalytic activity for oxygen evolution reaction (OER), which achieved an ultra-low overpotential of 199.5 mV at 10 mA cm−2. [Display omitted] • The NiTe nanosheet offered outstanding specific capacitance of 808.9 F g−1. • Superior durability of 91.4% retention during 60,000 cycles. • The NiTe@NF electrode delivered a small Tafel slope and a low overpotential. • Self-supporting NiTe nanosheets were prepared within 150 s via a microwave method. [ABSTRACT FROM AUTHOR]

Rare-earth (RE) zirconate pyrochlores, of low thermal conductivity and high temperature stability, are widely considered as a candidate material group for thermal barrier coatings (TBCs). Doping of a RE zirconate pyrochlore has been shown to be one possible method towards additional reduction in the thermal conductivity. Focusing on lanthanum zirconate (La 2 Zr 2 O 7) as a representative RE zirconate pyrochlore, we systematically investigated the effect of various doping elements, Gd, Y, Yb, In, Sc, Ce and Hf, on the thermal conductivity. A complete computational route, based on first-principles calculations, to predict the reduction of thermal conductivity by doping, has been developed. Employing first-principles calculations combined with thermodynamic modeling, the defects resulted from doping are explicitly clarified, with their concentrations determined considering the chemical environment. The phonon-defect scattering is then evaluated and the resultant reduction of thermal conductivity is determined from single-mode relaxation-time approximation. Good agreement has been achieved between our model predictions and available experimental data. The present study established a complete computational route, based on first-principles calculations, to predict the reduction of thermal conductivity by doping, not only for RE zirconate pyrochlores, but also for other complex oxide ceramics. Image 1 • Lanthanum zirconate (La 2 Zr 2 O 7) with various doping elements were studied. • The types and concentration of defects resulted from doping were identified. • The reductions of thermal conductivity (κ) by various dopants were evaluated. • The validity of our approach is confirmed by comparison with experimental data. • A computational route was developed to evaluate κ for complex oxides with doping. [ABSTRACT FROM AUTHOR]