The Substitution of Rare-Earth Gd in BaScCuTe3 Realizing the Band Degeneracy and the Point-Defect Scattering toward Enhanced Thermoelectric Performance.

Zintl compounds have continuously received significant attention, primarily due to their structural characteristics that align with the properties of the electron crystal and phonon glass. In this study, the crystal structure and thermoelectric properties of the quaternary Zintl chalcogenide BaScCuTe3 are investigated. The band structure calculations for BaScCuTe3 reveal a slight energy split of 0.08 eV between the second valence band and the valence band maximum, suggesting the presence of multiband-transport behaviors. Substitution of rare earth Gd for Sc is conducted, which significantly increases the hole concentration from 4.1 × 1019 cm-3 to 8.2 × 1019 cm-3 at room temperature. Meanwhile, the Seebeck coefficient increases because of the participation of the second valence band. A maximum power factor of 6.56 µW/cm·K2 at 773 K is obtained, which is 72% higher than that of the pristine sample. Moreover, the lattice thermal conductivity decreases from 0.57 W/m·K for BaScCuTe3 to 0.48 W/m·K for BaSc0.97Gd0.03CuTe3 at 773 K, owing to the introduction of point-defect scattering. As a result, there is a noteworthy improvement in the thermoelectric figure of merit zT, increasing from 0.44 for the undoped sample to 0.85 for BaSc0.98Gd0.02CuTe3. Considering these findings, BaScCuTe3 exhibits great potential and holds promise for further investigation in the field of thermoelectric materials.

Aerogel for Highly Efficient Photocatalytic Degradation.

Photocatalysis is one of the effective ways to degrade pollutant antibiotics. Agar is used as the adsorption module to provide abundant pore structure. Carbon dots (CDs) are selected as light energy conversion components. Graphitic carbon nitride (g-C3N4) is used as the main material of the catalyst. Agar/CDs/g-C3N4-functionalized aerogel with a unique 3D pore structure is assembled. The Agar/CDs/g-C3N4 aerogel shows the highest photocurrent density, which is 3.7 times that of agar, 2.4 times that of 3-g-C3N4 and 1.6 times that of Agar/g-C3N4 aerogel. Compared with 3-g-C3N4 and Agar/g-C3N4 aerogel, which can completely remove AMX after 75 min, Agar/CDs/g-C3N4 aerogel can degrade amoxicillin (AMX) completely after 45 min of illumination. The reason is that Agar/CDs/g-C3N4 aerogel has a larger specific surface area, richer functional groups, a wider spectral range, higher photocurrent density and better carrier migration and separation efficiency. It is a good strategy with which to combine the effects of each component in the ternary system for the efficient photocatalysis of organic pollutants.

Two Birds with One Stone: Micro/Nanostructured SiOx Cy Composites for Stable Li-Ion and Li Metal Anodes.

Developing stable silicon-based and lithium metal anodes still faces many challenges. Designing new highly practical silicon-based anodes with low-volume expansion and high electrical conductivity, and inhibiting lithium dendrite growth are avenues for developing silicon-based and lithium metal anodes, respectively. In this study, SiOx Cy microtubes are synthesized using a chemical vapor deposition method. As Li-ion battery anodes, the as-prepared SiOx Cy not only combines the advantages of nanomaterials and the practical properties of micromaterials, but also exhibits high initial Coulombic efficiency (80.3%), low volume fluctuations (20.4%), and high cyclability (98% capacity retention after 1000 cycles). Furthermore, SiOx Cy , as a lithium deposition substrate, can effectively promote the uniform deposition of metallic lithium. As a result, low nucleation overpotential (only 6.0 mV) and high Coulombic efficiency (≈98.9% after 650 cycles, 1.0 mA cm-2 and 1.0 mAh cm-2 ) are obtained on half cells, as well as small voltage hysteresis (only 9.5 mV, at 1.0 mA cm-2 ) on symmetric cells based on SiOx Cy . Full batteries based on both SiOx Cy and SiOx Cy @Li anodes demonstrate great practicality. This work provides a new perspective for the simultaneous development of practical SiOx Cy and dendrite-free lithium metal anodes.

Aerogel Assembled by Two Types of Carbon Nanoparticles for Efficient Removal of Heavy Metal Ions.

Both sodium alginate and polyethyleneimine (PEI) have a good ability to adsorb heavy metal ions. PEI and sodium alginate were used as important precursors to synthesize positively charged carbon nanoparticles (p-CNDs) with hydroxyl and carboxyl, and negatively charged carbon nanoparticles (n-CNDs) with amino, respectively. The carbon nanoparticles (CNDs) aerogel with a large specific surface area and rich functional groups were constructed by self-assembled p-CNDs and n-CNDs via electrostatic attraction for adsorption of heavy metal ions in water. The results show that CNDs aerogel has good adsorption properties for Pb2+ (96%), Cu2+ (91%), Co2+ (86%), Ni2+ (82%), and Cd2+ (78%). Furthermore, the fluorescence emission intensity of CNDs aerogel will gradually decrease with the increase in the adsorption rate, indicating that it can detect the adsorption process synchronously. In addition, the cytotoxicity test reveals that CNDs have good biocompatibility and will not cause secondary damage to biological cells.

Significant enhancement of scintillation performance by inducing oxygen vacancies in alkali metal ion (A+ = Li+, Na+, K+)-incorporated (Lu, Sc)BO3:Ce.

The incorporation of Sc3+ can stabilize calcite-phase LuBO3:Ce3+ to grow large-sized single crystals but leads to the significant degradation of scintillation performance. In the present work, alkali metal ion (A+ = Li+, Na+, K+)-incorporated (Lu, A, Sc)BO3:Ce was rapidly synthesized in batches via a high-throughput sol-gel method. The aliovalent substitution of Lu3+ with A+ is balanced by the generation of oxygen vacancies by forming complexes. Thanks to the increased oxygen vacancies, the luminescence and XEL intensity of (Lu, Li, Sc)BO3:Ce are significantly enhanced by 2.2 times and 1.9 times, respectively. Further, the incorporation of A+ is attributed to the improved transition efficiency of charge carriers. The prepared scintillation screen fabricated with LASBO:Ce and PMMA shows that the spatial resolution can reach 8.6 lp mm-1, indicating its potential application in efficient and low-cost non-destructive X-ray detection. This work is of great significance in improving the luminescence and scintillation performance of (Lu, Sc)BO3:Ce single crystals and thin films and their application in the scintillation field.

Multiple Color Emission of Mechanoluminescence and Photoluminescence from SrZnSO: Bi3+ for Multimode Anticounterfeiting.

Mechanoluminescence materials that emit light under mechanical stimulation have attracted widespread attention in sensing, anticounterfeiting, and imaging applications. In this study, a series of Sr1-xBixZnSO (0.001 ≤ x ≤ 0.1) samples was synthesized by the method of high temperature solid-state reaction. It is worth noting that the distortion degree of the SrO3S3 octahedron was increased with increasing Bi3+ concentration, and the color manipulated Sr1-xBixZnSO which can emit different photoluminescence (blue to dark blue and finally red) and mechanoluminescence (orange to red) colors is obtained. Moreover, the deep traps can stably store and provide electronic supplements in shallow traps released under mechanical stimulation. Therefore, devices made of SrZnSO:Bi3+ phosphor and polydimethylsiloxane (PDMS) can be used as thermo-mechano-opto three-mode anticounterfeiting. The ML intensity is linear to the external load and can be utilized for stress sensing or imaging.

Efficient energy transfer from Bi3+ to Mn2+ in CaZnOS for WLED application.

A series of Bi3+ and Mn2+ co-doped CaZnOS phosphors with a tunable emission color have been synthesized by a high temperature solid-state reaction method. Their crystal structure, spectroscopic properties, energy transfer and thermal quenching have been investigated systematically. An intense blue-green emission band at 485 nm and a red emission band at 616 nm were observed at an excitation wavelength of 375 nm, owing to the 3P1,0→1S0 transition of Bi3+ and the 4T1(4G) →6A1(6S) transition of Mn2+, respectively. The tunable color from blue-green, white light to red light can be obtained by varying the Mn2+ ion concentration from 0.005 to 0.015 in CaZnOS:Bi3+. The decay time decreased from 642 to 273 ns with the Mn2+ ion concentration x increasing from 0.005 to 0.015, and the energy transfer efficiency ηT can reach up to 65% in the CaZnOS:Bi3+,0.015Mn2+ phosphor. As the temperature increases from 300 to 420 K, the emission intensity is maintained at 67%, and the activation energy Ea is estimated to be 0.28 eV. An LED fabricated using CaZnOS:Bi3+,0.01Mn2+ exhibited the chromaticity coordinates and corrected color temperature (CCT) of (0.338, 0.364) and 4655 K, respectively. These results validate the promising applications of the CaZnOS:Bi3+,Mn2+ phosphor in UV white LEDs.

Improved Phase Stability and Enhanced Luminescence of Calcite Phase LuBO3:Ce3+ through Ga3+ Incorporation.

The application of LuBO3:Ce3+ (LBO:Ce) crystal as an excellent scintillation material has been limited due to its poor phase stability at high temperature or high pressure, so improving the phase stability is essential for promoting its development. Ga stabilized LuBO3:Ce3+ (LGBO:Ce) is synthesized by solid-state reaction at 1200 °C. Powder X-ray diffraction patterns and Raman spectra at ambient pressure show that all the samples are pure calcite phase. In situ high-pressure synchrotron radiation XRD patterns illustrate that calcite phase LGBO:Ce exhibits more excellent phase stability than that of LBO:Ce under high pressure due to the superior compressibility of the [GaO6] octahedral unit. The optical band gap of LGBO decreases from 5.58 to 4.64 eV after introducing 10% Ga, which leads to the decreased nonradiative transition and about double luminescence intensity as expected. More interestingly, the charge transition from O2- to Ce4+ is observed at about 290 nm in the absorption spectra. The X-ray photoelectron spectroscopy spectra indicate the ratio of Ce4+/Ce3+ increases with increasing concentration of Ga3+, which can be attributed to the variation of energy separation between the 4f ground state of Ce3+ and the Fermi energy level position. In contrast to the enhancement of PL intensity, the integrated X-ray excited luminescence intensity decreases after Ga3+ incorporation attributing to the result of both decreased effective atomic number and ionization energy between 5d1 level and conduction band. The thermal luminescence spectra show that after the incorporation of Ga3+ the oxygen vacancy and intrinsic defects in LBO remain unchanged but that the concentration of oxygen vacancy significantly reduces. The mechanism of Ga3+ incorporation on phase stability and luminescence properties of LBO:Ce has been proposed and discussed systematically.

One Stone, Two Birds: pH- and Temperature-Sensitive Nitrogen-Doped Carbon Dots for Multiple Anticounterfeiting and Multiple Cell Imaging.

Carbon dots (CDs) as new fluorescent materials with excellent fluorescence properties have shown enormous potential applications, especially in anticounterfeiting and cell imaging. Herein, nitrogen-doped CDs (NCDs) with excellent biocompatibility were prepared by a simple thermal sintering method. An extremely large red shift (∼130 nm) of the emission peak was observed when the excitation wavelength changes from 355 to 550 nm, indicating that NCDs are excellent fluorescent labeling materials for multiple cell imaging. On the other hand, NCDs showed obvious changes of emission intensity and peak position when the temperature increased from 223 to 323 K and the pH values changed from 1 to 13, respectively, which has been demonstrated by the "horse" pattern printed with NCD water-soluble fluorescent inks. The nontoxic NCDs dispersed in a multiple matrix are highly sensitive to excitation wavelength, temperature, and pH, indicating their great potential application in multiple anticounterfeiting and multiple cell imaging.

Greatly Enhanced Faradic Capacities of 3D Porous Mn3O4/G Composites as Lithium-Ion Anodes and Supercapacitors by C-O-Mn Bonding.

Through C-O-Mn bonding, graphene nanosheets are homogeneously dispersed in porous Mn3O4 to take full advantages of porous Mn3O4 and graphene nanosheets, making the as-formed three-dimensional porous Mn3O4/reduced graphene oxide (rGO) composite exhibit good electrochemical performance. Besides, C-O-Mn bonding is demonstrated to greatly promote the Faradic reactions of the composite, resulting in the enhancement of its real capacity in supercapacitor (SC) electrodes as well as lithium-ion battery (LIB) anodes. By simply fine-tuning the content of graphene (<7 wt %), the composite with 2.8 wt % of rGO delivers a high capacitance of 315 F g-1 at 0.5 A g-1 with a high rate capability of 64.7% at 30 A g-1 and an excellent cycling stability of 105% (5 A g-1, 5000 cycles) as an SC electrode. Also, the one with 6.9 wt % rGO can present a reversible capacity of more than 1500 mAh g-1 at 0.05 A g-1 as the LIB anode, the highest value reported to date, which remains 561 mAh g-1 at 1 A g-1.

Two-dimensional mesoporous ZnCo2O4 nanosheets as a novel electrocatalyst for detection of o-nitrophenol and p-nitrophenol.

Novel mesoporous ZnCo2O4 (meso-ZnCo2O4) nanosheets were synthesized by a simple hydrothermal method for detection of o-nitrophenol (ONP) and p-nitrophenol (PNP). The resultant meso-ZnCo2O4 nanosheets possess more catalytic active sites than other structures, which enhance the catalysis properties for the electrochemical detection of nitrophenol. This sensor exhibits a wide linear detection range (1-4000 and 1-4000 µM) and high sensitivity (0.256 and 0.318 µA µM-1 cm-2), as well as low detection limit (0.3 and 0.3 µM), for ONP and PNP, respectively. In addition, the fabricated sensor reveals excellent reproducibility, stability and selectivity.

Weak Interactions under Pressure: hp-CuBi and Its Analogues.

The metastable binary compound hp-CuBi was obtained from the direct chemical reaction between copper and bismuth at a pressure of 5 GPa and a temperature of 720 K. The atomic arrangement comprises slabs of puckered Cu layers sandwiched between Bi planes. The QTAIM charges calculated for compounds of bismuth with transition metals reveal negligible charge transfer for hp-CuBi. Analysis of the chemical bonding with position-space techniques discloses multicenter interactions within the Bi-Cu-Bi slabs and lone-pair interactions of the van der Waals type between these entities. hp-CuBi exhibits metal-type electrical conductivity with superconductivity below Tc =1.3 K.

A Novel Small-Molecule Compound of Lithium Iodine and 3-Hydroxypropionitride as a Solid-State Electrolyte for Lithium-Air Batteries.

A novel small-molecule compound of lithium iodine and 3-hydroxypropionitrile (HPN) has been successfully synthesized. Our combined experimental and theoretical studies indicated that LiIHPN is a Li-ion conductor, which is utterly different from the I(-)-anion conductor of LiI(HPN)2 reported previously. Solid-state lithium-air batteries based on LiIHPN as the electrolyte exhibit a reversible discharge capacity of more than 2100 mAh g(-1) with a cyclic performance over 10 cycles. Our findings provide a new way to design solid-state electrolytes toward high-performance lithium-air batteries.

Zintl-phase Sr3LiAs2H: crystal structure and chemical bonding analysis by the electron localizability approach.

The compound Sr3 LiAs2 H was synthesized by reaction of elemental strontium, lithium, and arsenic, as well as LiH as hydrogen source. The crystal structure was determined by single-crystal X-ray diffraction: space group Pnma; Pearson symbol oP28; a = 12.0340(7), b = 4.4698(2), c = 12.5907(5) Å; V = 677.2(1) Å(3) ; RF = 0.047 for 1021 reflections and with 36 parameters refined. The positions of the hydrogen atoms were first revealed by the electron localizability indicator and subsequently confirmed by crystal structure refinement. In the crystal structure of Sr3 LiAs2 H the metal atoms are arranged in a Gd3 NiSi2 -type motif, whereas the hydrogen atoms are arranged in a distorted tetrahedral environment formed by strontium. The calculated band structure revealed that Sr3 LiAs2 H is a semiconductor, which is in agreement with its diamagnetic behavior. Thus, Sr3 LiAs2 H is considered as a (charge-balanced) Zintl phase.

Dimensional Reduction From 2D Layer to 1D Band for Germanophosphates Induced by the "Tailor Effect" of Fluoride.

The "tailor effect" of fluoride, exclusively as a terminal rather than a bridge, was applied successfully to design low-dimensional structures in the system of transition metal germanophosphates for the first time. Two series of new compounds with low-dimensional structures are reported herein. K[M(II)Ge(OH)2(H0.5PO4)2] (M = Fe, Co) possess flat layered structures built from single chains of edge-sharing M(II)O6 and GeO6 octahedra interconnected by HPO4 tetrahedra. Their fluorinated derivatives, K4[M(II)Ge2F2(OH)2(PO4)2(HPO4)2]·2H2O (M = Fe, Co), exhibit band structures of two four-membered ring germanium phosphate single chains sandwiched by M(II)O6 octahedra via corner-sharing. Both of these structures contain anionic chains of the condensation of four-membered rings built from alternating GeO4Φ2 (Φ = F, OH) octahedra and PO4 tetrahedra via sharing common GeO4Φ2 (Φ = F, OH) octahedra, the topology of which is the same as that of the mineral kröhnkite [Na2Cu(SO4)2·2H2O]. Note that the switch from the two-dimensional layered structure to the one-dimensional band structure was performed simply by the addition of a small amount of KF·2H2O to the reaction mixture. This structural alteration arises from the incorporation of one terminal F atom to the coordination sphere of Ge, which breaks the linkage between the transition metal and germanium octahedra in the layer to form the band structure.

Low-temperature vaterite-type LuBO3, a vacancy-stabilized phase synthesized at high temperature.

Low-temperature vaterite-type LuBO(3) (π-LBO) was prepared by a solid-state reaction method at high temperature. The reasoning of the existence of vacancy-stabilized π-LBO was investigated for the first time using neutron diffraction patterns, Fourier transform infrared (FT-IR) spectra, and high-resolution transmission electron microscopy. The results clearly demonstrated that the B and O vacancies in π-LBO came into being during the heating process. The existence of an open B(3)O(9) ring consisting of BO(3) and BO(4) units in π-LBO due to the B and O vacancies was demonstrated by FT-IR. The vacuum ultraviolet-ultraviolet spectroscopic properties of π-LBO were studied in detail. In addition, the luminescence mechanism of Ce(3+) in π-LBO was put forward and discussed with that of calcite-type LuBO(3) (ß-LBO).

Low-melting imidazolium-based salts with the paramagnetic reineckate-analogue anion [Cr(NCS)4(bipy)]- (bipy = 2,2'-bipyridine): syntheses, properties, and structures.

In order to investigate the potential ionic liquid properties of Reineckate-analogue materials, four new salts, consisting of the heteroleptic [Cr(NCS)(4)(bipy)](-) complex anion and imidazolium-based cations A(+) = 1-ethyl-3-methylimidazolium, 1-n-butyl-3-methylimidazolium, pentamethylimidazolium, and 1,3-dimethyl-2,4,5-triphenylimidazolium, were investigated. Their structures were established by single-crystal X-ray diffraction. The compounds are paramagnetic with effective magnetic moments in the range of those expected by the number of unpaired spins of the chromium(III) ion. All melting points are above 100 °C, which prevents us from calling these compounds "ionic liquids". Nevertheless, they are low for salts of this constitution and may be useful for molten salt reactions. Cyclic voltammetry measurements show no reversible electron-transfer steps.

Structural assembly from phosphate to germanophosphate by applying germanate as a binder.

Structural assembly from phosphate to germanophosphate by applying germanate as a binder has been achieved. Two isotypic porous compounds, K3[M(II)4(HPO4)2][Ge2O(OH)(PO4)4]·xH2O (M(II) = Fe, Cd; x = 2 for Fe and 3 for Cd, denoted as KFeGePO-1 and KCdGePO-1, respectively), contain a known transition-metal phosphate (TMPO) layer, (∞)(2){[M2(HPO4)3]2­}, which is built from chains of trans-edge-sharing MO6 octahedra bridged by MO5 trigonal bipyramids that were further linked and decorated by phosphate tetrahedra. The layers are bound by infinite chains of GeO5(OH) octahedra, resulting in a 3D open-framework structure with 1D 12-ring channels that are occupied by K+ ions and water molecules. The curvature of the TMPO layers and shape of the 12-ring windows can be tuned by the transition metals because of their Jahn­Teller effect.

Synthesis, structure, and properties of two Zintl phases around the composition SrLiAs.

Two atomic arrangements were found near the equiatomic composition in the strontium-lithium-arsenic system. Orthorhombic o-SrLiAs was synthesized by reaction of elemental components at 950 °C, followed by annealing at 800 °C and subsequent quenching in water. The hexagonal modification h-SrLi(1-x)As was obtained from annealing of o-SrLiAs at 550 °C in dynamic vacuum. The structures of both phases were determined by single-crystal X-ray diffraction: o-SrLiAs, structure type TiNiSi, space group Pnma, Pearson symbol oP12, a = 7.6458(2) Å, b = 4.5158(1) Å, c = 8.0403(3) Å, V = 277.61(2) Å(3), R(F) = 0.028 for 558 reflections; h-SrLi(1-x)As, structure type ZrBeSi, space group P6(3)/mmc, Pearson symbol hP6, a = 4.49277(9) Å, c = 8.0970(3) Å, V = 141.54(1) Å(3), RF = 0.026 for 113 reflections. The analysis of the electron density within the framework of the quantum theory of atoms in molecules revealed a charge transfer according to the Sr(1.3+)Li(0.8+)As(2.1-), in agreement with the electronegativities of the individual elements. The electron localizability indicator distribution indicated the formation of a 3D anionic framework [LiAs] in o-SrLiAs and a rather 2D anionic framework [LiAs] in h-SrLi(1-x)As. Magnetic susceptibility measurements point to a diamagnetic character of both phases, which verifies the calculated electronic density of states.

A promising mid-temperature thermoelectric material candidate: Pb/Sn-codoped In4PbxSnySe3.

A facile polycrystalline Pb/Sn-codoped In4Pb0.01SnySe3 material is obtained, its thermoelectric performance is evaluated, and the intrinsic reasons have been studied. This material shows an excellent ZT value of 1.4 at 733 Kelvin, among the best values of the relative materials, thus making it a promising candidate for the mid-temperature thermoelectric application.