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Zero-dimensional (0D) hybrid metal halides are under intensive investigation owing to their unique physical properties, such as the broadband emission from highly localized excitons that is promising for white-emitting lighting. However, fundamental understanding of emission variations and structure–property relationships is still limited. Here, by using pressure processing, we obtain robust exciton emission in 0D (C9NH20)6Pb3Br12 at room temperature that can survive to 80 GPa, the recorded highest value among all the hybrid metal halides. In situ experimental characterization and first-principles calculations reveal that the pressure-induced emission is mainly caused by the largely suppressed phonon-assisted nonradiative pathway. Lattice compression leads to phonon hardening, which considerably weakens the exciton–phonon interaction and thus enhances the emission. The robust emission is attributed to the unique structure of separated spring-like [Pb3Br12]6− trimers, which leads to the outstanding stability of the optically active inorganic units. Our findings not only reveal abnormally robust emission in a 0D metal halide, but also provide new insight into the design and optimization of local structures of trimers and oligomers in low-dimensional hybrid materials.

A new compound K 2 Cu 2 GeS 4 was successfully synthesized by using molten thiourea reactive flux method. The structure was determined by single crystal X-ray diffraction. The compound crystallizes in the monoclinic system of space group P 2/ c with a unit cell of a = 7.063 (3) A, b = 5.435 (3) A, c = 11.037 (6) A and β = 112.83 (3)°. The crystal structure of K 2 Cu 2 GeS 4 is composed of defective anti -PbO like [Cu 2 GeS 4 ] 2− layers which are interleaved by K + cations. This compound is a semiconductor with an indirect band gap of 2.3 (1) eV, which is derived from optical absorption spectrum. First principles calculations reveal that K 2 Cu 2 GeS 4 has interesting intermediate bands consisting of Ge-4 s and S-3 p orbitals. This new semiconductor is potentially suitable for solar photocatalytic and photoelectric applications.

The mixed-metal sulfide compound with the formula Ba2Fe0.6V1.4S6 was successfully synthesized via solid-state reaction. Ba2Fe0.6V1.4S6 has a quasi-one-dimensional structure and crystallizes in the hexagonal space group P63/mmc. The structure is composed of face-sharing anion octahedron [MS6]8– (M = V or Fe) units to construct infinite chains along the c axis, in which the Fe atoms randomly occupy the V sites. The Ba2+ ions reside between adjacent chains. Magnetic susceptibility measurements reveal a transition between paramagnetism and ferromagnetism around 25 K. The small polaron hopping (SPH) conduction behavior has been observed in the higher temperature region (75–300 K), while in the lower temperature region (25–74 K), the resistivity features a variable range hopping mechanism (VRH). The analysis of density of states indicates that Fe-3dz2 and S-3p states mainly dominate the valence band maximum, while Fe-3dz2 states contribute significantly to the magnetic susceptibility.

Layered sulfides with high selectivity for binding heavy metal ions and radionuclide ions are promising materials in effluent treatment and water purification. Here we present a rationally designed layered sulfide K

The layered oxyselenides with the formula

Multiband materials have received increasing attention due to their superior solar absorption properties. Here we design a new multiband compound, namely Ba5Bi2Co2S10, which crystallizes in the space group C22h-P21/m (No. 11) of the monoclinic system. Ba5Bi2Co2S10 is composed of one-dimensional 1∞[Bi2Co2S10]10- chains along the a axis. The adjacent chains are separated by Ba2+ ions. The optical band gap of the compound is 1.05 eV and 0.74 eV, presenting typical multi-absorption characteristics. First-principles calculations, which are perfectly consistent with the experimental results, show that the hybrid coupling effect between Co and S gives rise to multiband characteristics. Evident optoelectronic conversion properties were observed under visible light illumination with a photocurrent density of 4.0 mA cm-2 at 1 V.

A new nonlinear optical (NLO) oxysulfide, Sr

Noncentrosymmetric MoS

A new two-dimensional (2D) layered oxysulfide, namely, SrOCuSbS

Although IrSe2 is a superior oxygen evolution catalyst, its electronic structure lacks active sites for hydrogen production and hinders its use as a bifunctional catalyst. The intercalation of Bi atoms into the IrSe2 framework regulates its electronic structure with the improvement of performance. Herein, novel bismuth inserted iridium‐based selenide (BiIr4Se8) is synthesized via solid‐state reaction. Interestingly, BiIr4Se8 exhibits impressive activities with dual functionality in pH‐universal electrolytes. It achieves small overpotentials at 10 mA cm−2 toward hydrogen evolution (85 mV in acid and 252 mV in alkali) and oxygen evolution (379 mV in acid and 364 mV in alkali), which overmatches the benchmarking noble metal‐based electrocatalysts. When served as the bifunctional electrocatalyst to drive a water electrolyzer, BiIr4Se8 affords 10 mA cm−2 at a voltage of 1.56 and 1.52 VRHE in 0.5 m H2SO4 and 1 m KOH, far exceeding the Pt/C||RuO2 and other published materials. Theoretical calculations show that a narrow bandgap is obtained due to the induced intermediate band derived from the combination of the p orbitals of Bi atoms and structure reconstruction, which promotes the electrocatalytical performance. This research introduces a new strategy to design channel structures and sheds light on their applications for water splitting.

A new platinum-based ternary selenide, Pt3Pb2Se2 was successfully synthesized at 1123 K by using a traditional solid-state method. It crystallizes in a orthorhombic structure with the Cmcm space group, and consists of quasi-2D [Pt3Pb2Se2] layers connected by inherent Pt–Pb bonds. It is related to the parkerite structures with half transition metal occupation. Therefore, it belongs to the half anti-perovskite family structure. The R-T curve reveals its metallic behavior and shows high conductivity (RRR = 20.5) at room temperature. The X-ray photoelectron and ultraviolet photoelectron spectroscopy spectrums were collected. It has low work function (ϕ = −4.02 eV). First principles calculations were consistent with the experimental results.

The mixed-metal title compound, BaCu1/3Ta2/3S3 [barium copper(II) tantalum(V) trisulfide], was prepared through solid-state reactions. The crystal structure adopts the BaTaS3 structure type and consists of face-sharing [MS6] (M = Ta,Cu) octahedra (point-group symmetry -3m.) that are condensed into infinite chains along [001]. Adjacent chains are linked through the barium cations (site symmetry -6m2), which exhibit a coordination number of twelve. The M site is occupied by 2/3 of TaV and 1/3 of CuII, whereby the average M—S distances are slightly longer than those of ordered BaTaS3. The classical charge balance of the title compound can be represented by [Ba2+] [(Ta/Cu)4+] [S2−]3.

Exploring novel electrocatalysts with prominent performance is highly demanded for electrochemical hydrogen evolution. As one family member of layered transition-metal dichalcogenides (TMDs), metallic niobium disulfide (NbS2) with intrinsic basal plane activity might be a promising candidate once its electrical and structural characteristics are optimized. Here, we develop novel electrocatalysts by incorporating palladium (Pd) atoms into the van der Waals gaps of NbS2 to form new compounds PdxNbS2 (x = 0−0.23). On the basis of single crystal structure refinement and theoretical calculations, the Pd atoms act as atomic pillars to expand the interlayer spacing of NbS2 and boost the basal plane activity with a drop of Gibbs free energy for hydrogen adsorption to 0.06 eV on neighboring S atoms, resulting in more protons to adsorb and react. In addition, pillared Pd stabilizes the crystal structure by connecting the NbS2 interlayers with [PdS6] octahedra. All these merits endow Pd0.23NbS2 with superior electrochemical activity and durability, achieving 10 mA cm−2 at a low overpotential of 157 mV with a negligible change in 12 h. This unique atomic pillar effect for optimizing the electrocatalytic performance of PdxNbS2 demonstrates a functional and powerful strategy to develop efficient TMD-based electrocatalysts.

TiO

The 2H molybdenum disulfide (MoS

2H MoS2 has been intensively studied because of layer-dependent electronic structures and novel physical properties. Though the metastable 1T MoS2 with the [MoS6] octahedron was observed from the microscopic area, the true crystal structure of 1T phase has not been determined strictly. Moreover, the true physical properties have not been demonstrated from experiments due to the challenge for the preparation of pure 1T MoS2 crystals. Here, we successfully synthesized the 1T MoS2 single crystals and re-determined the crystal structure of 1T MoS2 from single-crystal X-ray diffraction. 1T MoS2 crystalizes in space group P-3m1 with a cell of a = b = 3.190(3) {\AA} and c = 5.945(6) {\AA}. The individual MoS2 layer consists of MoS6 octahedron sharing edge with each other. More surprisingly, the bulk 1T MoS2 crystals undergo a superconducting transition of Tc = 4 K, which is the first observation of superconductivity in pure 1T MoS2 phase.

We report the use of 2H-NbS2 film as a novel counter electrode in perovskite solar cells fabricated with a cold isostatic pressing method. The 2H-NbS2 film, which was prepared through an exfoliation method followed by restacking from LixNbS2 powder, shows high electrical conductivity of 8.7 × 103 S cm−1 and work function of 5.20 eV. The two-dimensional transition metal dichalcogenide was used for the first time as a counter electrode in meso-structured perovskite solar cells. Through this process, we demonstrated a new alternative to noble metals. The perovskite solar cell base on the 2H-NbS2 counter electrode showed an open-circuit voltage of 1.046 V, comparable to that of gold, and a power conversion efficiency of 8.3%.

Nano TiO2 is investigated intensely due to extraordinary photoelectric performances in photocatalysis, new-type solar cells, etc., but only very few synthesis and physical properties have been reported on nanostructured TiO or other low valent titanium-containing oxides. Here, a core-shell nanoparticle made of TiO core covered with a ≈5 nm shell of amorphous TiO1+x is newly constructed via a controllable reduction method to synthesize nano TiO core and subsequent soft oxidation to form the shell (TiO1+x ). The physical properties measurements of electrical transport and magnetism indicate these TiO@TiO1+x nanocrystals are a type-ІІ superconductor of a recorded Tconset = 11 K in the binary Ti-O system. This unusual superconductivity could be attributed to the interfacial effect due to the nearly linear gradient of O/Ti ratio across the outer amorphous layer. This novel synthetic method and enhanced superconductivity could open up possibilities in interface superconductivity of nanostructured composites with well-controlled interfaces.

2H MoS

The mixed-metal sulfide compound with the formula Ba

Since interface superconductivity was discovered at the interface between two insulating layers LaAlO

In the structure of BaCu1/3Ta2/3S3, the Cu and Ta atoms are occupationally disordered on the same site in a ratio of 1/3:2/3., The mixed-metal title compound, BaCu1/3Ta2/3S3 [barium copper(II) tantalum(V) tris­ulfide], was prepared through solid-state reactions. The crystal structure adopts the BaTaS3 structure type and consists of face-sharing [MS6] (M = Ta,Cu) octa­hedra (point-group symmetry -3m.) that are condensed into infinite chains along [001]. Adjacent chains are linked through the barium cations (site symmetry -6m2), which exhibit a coordination number of twelve. The M site is occupied by 2/3 of TaV and 1/3 of CuII, whereby the average M—S distances are slightly longer than those of ordered BaTaS3. The classical charge balance of the title compound can be represented by [Ba2+] [(Ta/Cu)4+] [S2−]3.

The size effect on the bending deformation behaviour of magnetron-sputtered La 57 Al 25 Co 18 , Cu 50 Zr 50 and Fe 70 Y 8 B 22 glassy films was investigated. The transition of the deformation mode from highly localized to non-localized occurs as the film thickness reduces below the critical value, which does not exhibit a distinct dependence on Poisson’s ratio. By combining the already-reported critical size for deformation mode transition in various metallic glasses, it is found that the critical size is primarily proportional to the homologous temperature.

Recently, metastable polymorphs of MoS2 (1T, 1T’, 1T‴) have raised much attention due to their rich crystal structures and intriguing physicochemical properties. They are often derived from alkali metal intercalated compounds of MoS2, Ax(H2O)yMoS2 (A = alkali metal), by topotactic reaction. In order to make clear the deintercalation process, it is demanded to elucidate the compositions and crystal structures of Ax(H2O)yMoS2. Here, we report the synthesis of high-quality Ax(H2O)yMoS2 (A = K, Rb, Cs) single crystals, determine their crystal structures and investigate the physical properties. The three new quasi two-dimensional compounds crystallize in the identical monoclinic P21/m (No.11) space group determined by single crystal X-ray diffraction. Their structures consist of ordered MoS2 layers, which are intercalated by disordered hydrated A+ cations. Each layer contains edge-sharing [MoS6] octahedral, forming one-dimensional Mo zigzag chains along the b-axis. The resistivity of Ax(H2O)yMoS2 increases with the decrease of temperature, which is the typical semiconducting behavior. The apparent difference in the resistivity of the three compounds is mainly related to the number of electrons injected by alkali metal atoms. Magnetic measurements indicated that the three compounds are dominantly paramagnetic accompanied by weak ferromagnetic contributions.

Two isostructural compounds, Ba2SbO2SX (X = Br, I), have been successfully synthesized via solid state reaction. Their structures belong to the space group C 2 h 2 - P 21 / m (No. 11) of the monoclinic system. They feature a quasi-two-dimensional (2D) network of distorted capped trigonal prisms [XBa7]13+ along the a-b plane intercalated by [SbSO2]3- triangular pyramid. The optical band gaps of Ba2SbO2SBr and Ba2SbO2SI are 1.93 eV ad 2.03 eV, respectively. Ba2SbO2SI also exhibits an emission peak at 579 nm under 375 nm radiation. First-principles calculation reveals that the optical absorptions of Ba2SbO2SX are mainly attributed to the S-3p→Sb-5p transitions. The photoluminescence emission of Ba2SbO2SI is mainly contributed by the excitation of the states of the Sb−S bonds.

Pressure is a powerful tool to study iron-based superconductors. Here, we report systematic high-pressure transport and structural characterizations of the newly discovered superconductor FeS. It is found that superconductor FeS (tetragonal) partly transforms to a hexagonal structure at 0.4 GPa and then completely transforms to an orthorhombic phase at 7.4 GPa and finally to a monoclinic phase above 9.0 GPa. The superconducting transition temperature of tetragonal FeS was gradually depressed by pressure, different from the case in tetragonal FeSe. With pressure increasing, the S-Fe-S angles only slightly change but the anion height deviates farther from 1.38 Å. This change of anion height, together with the structural instability under pressure, should be closely related to the suppression of superconductivity. We also observed an anomalous metal-semiconductor transition at 6.0 GPa and an unusual increased resistance with further compression above 9.6 GPa. The former can be ascribed to the tetragonal-orthorhombic structural phase transition and the latter to the electronic structure changes of the high-pressure monoclinic phase. Finally, a phase diagram of tetragonal FeS as functions of pressure and temperature was mapped out for the first time, which will shed new light on understanding of the structure and physics of the superconducting FeS.

Boron, the most ideal lithium-ion battery anode material, demonstrates highest theoretical capacity up to 12 395 mA h g(-1) when forming Li5B. Furthermore, it also exhibits promising features such as light weight, considerable reserves, low cost, and nontoxicity. However, boron-based materials are not in the hotspot list because Li5B may only exist when B is in atomically isolated/dispersed form, while the aggregate material can barely be activated to store/release Li. At this time, an ingenious design is demonstrated to activate the inert B to a high specific capacity anode material by dispersing it in a Fe matrix. The above material can be obtained after an electrochemical activation of the precursors Fe2B/Fe and B2O3/Fe. The latter harvests the admirable capacity, ultrahigh tap density of 2.12 g cm(-3), excellent cycling stability of 3180 mA h cm(-3) at 0.1 A g(-1) (1500 mA h g(-1)) after 250 cycles, and superlative rate capability of 2650 mA h cm(-3) at 0.5 A g(-1), 2544 mA h cm(-3) at 1.0 A g(-1), and 1696 mA h cm(-3) at 2.0 A g(-1). Highly conductive matrix promoted reversible Li storage of boron-based materials might open a new gate for advanced anode materials.