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1.
Inorganic Bi-based perovskites have shown great potential in X-ray detection for their large absorption to X-rays, diverse low-dimensional structures, and eco-friendliness without toxic metals. However, they suffer from poor carrier transport properties compared to Pb-based perovskites. Here, we propose a mixed-halogen strategy to tune the structural dimensions and optoelectronic properties of Cs 3Bi 2I 9−nBr n (0≤n≤9). Ten centimeter-sized single crystals are successfully grown by the Bridgman technique. Upon doping bromine to zero-dimensional Cs 3Bi 2I 9, the crystal transforms into a two-dimensional structure as the bromine content reaches Cs 3Bi 2I 8Br. Correspondingly, the optoelectronic properties are adjusted. Among these crystals, Cs 3Bi 2I 8Br exhibits negligible ion migration, moderate resistivity, and the best carrier transport capability. The sensitivities in 100 keV hard X-ray detection are 1.33×10 4 and 1.74×10 4 μC Gy air−1 cm −2 at room temperature and 75 °C, respectively, which are the highest among all reported bismuth perovskites. Moreover, the lowest detection limit of 28.6 nGy air s −1 and ultralow dark current drift of 9.12×10 −9 nA cm −1 s −1 V −1 are obtained owing to the high ionic activation energy. Our work demonstrates that Br incorporation is an effective strategy to enhance the X-ray detection performance by tuning the dimensional and optoelectronic properties. 相似文献
2.
Developing bifunctional water-splitting photocatalysts is meaningful, but challenged by the harsh requirements of specific-facet single crystals with spatially separated reactive sites and anisotropic charge transfer paths contributed by well-built charge driving force. Herein, tunable ferroelectric polarization is introduced in Bi 4NbO 8Cl single crystal nanosheets to strengthen the orthogonal charge transfer channels. By manipulating the in-plane polarization from octahedral off-centering of Nb 5+ and out-of-plane polarization from lone pair electron effect of anisotropic Bi 3+, both the fast charge recombination in bulk catalyst and the process of charge trapping into surface states can be effectively modulated. Collaborating with modest polarization electric field and facet junction induced built-in electric field, cooperative charge tractive force is constructed, which reinforces the spatial separation and migration of photogenerated electrons and holes to {110} reductive site facet and {001} oxidation site facet, respectively. While excessive polarization charges impair the facet-selective charge separation characteristics and conversely promote charge recombination on the surface. As a result, polarity-optimized Bi 4NbO 8Cl shows an excellent H 2 and O 2 evolution rate of 54.21 and 36.08 μmol ⋅ h −1 in the presence of sacrificial reagents under visible light irradiation. This work unveils the function of ferroelectric polarization in tuning the intrinsic facet-selective charge transfer process of photocatalysts. 相似文献
3.
Realizing high photoluminescence quantum yield (PLQY) in the near-infrared (NIR) region is challenging and valuable for luminescent material, especially for thermally activated delay fluorescence (TADF) material. In this work, we report two achiral cyclic trinuclear Au(I) complexes, Au 3(4-Clpyrazolate) 3 and Au 3(4-Brpyrazolate) 3 (denoted as Cl−Au and Br−Au) , obtained through the reaction of 4-chloro-1H-pyrazole and 4-bromo-1H-pyrazole with Au(I) salts, respectively. Both Cl−Au and Br−Au exhibit TADF with high PLQY (>70 %) in the NIR I (700–900 nm) (λ max = 720 nm) region, exceeding other NIR−TADF emitters in the solid state. Photophysical experiments and theoretical calculations confirmed the efficient NIR−TADF properties of Cl−Au and Br−Au were attributed to the small energy gap Δ E(S1-T2) (S = singlet, T = triplet) and the large spin-orbital coupling induced by ligand-to-metal-metal charge transfer of molecular aggregations. In addition, both complexes crystallize in the achiral Pna2 1 space group (mm2 point group) and are circularly polarized light (CPL) active with maxima luminescent dissymmetry factor |g lum| of 3.4 × 10 −3 ( Cl−Au ) and 2.7 × 10 −3 ( Br−Au ) for their crystalline powder samples, respectively. By using Cl−Au as the emitting ink, 3D-printed luminescent logos are fabricated, which own anti-counterfeiting functions due to its CPL behavior dependent on the crystallinity. 相似文献
4.
Despite its electron deficiency, boron is versatile in forming multiple bonds. Transition‐metal–boron double bonding is known, but boron–metal triple bonds have been elusive. Two bismuth boron cluster anions, BiB 2O − and Bi 2B −, containing triple and double B−Bi bonds are presented. The BiB 2O − and Bi 2B − clusters are produced by laser vaporization of a mixed B/Bi target and characterized by photoelectron spectroscopy and ab initio calculations. Well‐resolved photoelectron spectra are obtained and interpreted with the help of ab initio calculations, which show that both species are linear. Chemical bonding analyses reveal that Bi forms triple and double bonds with boron in BiB 2O − ([Bi≡B−B≡O] −) and Bi 2B − ([Bi=B=Bi] −), respectively. The Bi−B double and triple bond strengths are calculated to be 3.21 and 4.70 eV, respectively. This is the first experimental observation of Bi−B double and triple bonds, opening the door to design main‐group metal–boron complexes with multiple bonding. 相似文献
5.
A family of perovskite light absorbers (NH 4) 3Sb 2I xBr 9−x (0≤ x≤9) was prepared. These materials show good solubility in ethanol, a low-cost, hypotoxic, and environmentally friendly solvent. The light absorption of (NH 4) 3Sb 2I xBr 9−x films can be tuned by adjusting I and Br content. The absorption onset for (NH 4) 3Sb 2I xBr 9−x films changes from 558 nm to 453 nm as x changes from 9 to 0. (NH 4) 3Sb 2I 9 single crystals were prepared, exhibiting a hole mobility of 4.8 cm 2 V −1 s −1 and an electron mobility of 12.3 cm 2 V −1 s −1. (NH 4) 3Sb 2I 9 solar cells gave an open-circuit voltage of 1.03 V and a power conversion efficiency of 0.51 %. 相似文献
6.
Constructing a heterojunction photocatalyst is a significant method to enhance photocatalytic activity because it can promote the separation of photogenerated carriers. Herein, amorphous/crystalline contact Bi 2S 3/Bi 4O 7 heterostructure was successfully synthesized by in-situ sulfidation of Bi 4O 7. The amorphous Bi 2S 3 is diffused on the surface of Bi 4O 7 rod, enhancing the visible light response and improving the transport of photogenerated carriers. Various characterizations confirm that the rapid separation of photogenerated carriers leads to increased photocatalytic performance. The optimized Bi 2S 3/Bi 4O 7 heterostructure photocatalyst (BiS-0.15) exhibits the highest Cr(VI) reduction (0.01350 min −1) and RhB oxidation (0.08011 min −1) activity, which is much higher than that of pure Bi 4O 7 and Bi 2S 3/Bi 4O 7 mixture under visible light irradiation. This work provides new insights into the construction of efficient novel photocatalysts. 相似文献
7.
By applying the potassium salts of cyclopentadienyl-phosphine ligands LK to CoCl 2, the corresponding cobalt chlorides ( 1 , L Co IICl) were prepared. By reducing complexes 1 with KHBEt 3 under a N 2 atmosphere, bridging end-on complexes, L Co I−N 2−Co I L ( 2 a and 2 b ), were successfully obtained. 15N 2-labeled [ 15N 2]- 2 a was prepared under 15N 2/ 14N 2 exchange in THF solution. L Co I−N 2−Co I L complex 2 a could react with P 4 molecules to release N 2 and generate a Co−P 4−Co moiety 4 . Further reduction of complex 2 b led to cleavage of a P−C bond in the cyclopentadienyl-phosphine ligand to provide novel μ-PCy 2-bridged Co 0−N 2 complex 5 . DFT calculations confirmed the experimental observations. 相似文献
8.
A series of five ternary octanuclear iodine-bromine-chlorine interhalides, [I 2Br 2Cl 4] 2− ( 1 ), [I 3BrCl 4] 2− ( 2 ), [I 4Br 2Cl 2] 2− ( 3 ), [I 2Br 4Cl 2] 2− ( 4 ) and [I 3Br 3Cl 2] 2− ( 5 ), have been rationally constructed in two steps. Firstly, addition of a dihalogen (ICl or IBr) to the triaminocyclopropenium chloride salt [C 3(NEt 2) 3]Cl forms the corresponding trihalide salt with [ICl 2] − or [BrICl] − anions, respectively. Secondly, addition of a half-equivalent of a second dihalogen, followed by crystallization at low temperature, gives the corresponding octahalide: addition of Br 2 and IBr to [ICl 2] − gives 1 and 2 , respectively, whereas addition of I 2, Br 2 and IBr to [BrICl] − gives 3 , 4 and 5 , respectively. The five octahalides were characterized by X-ray crystallography and far–IR spectroscopy. 相似文献
9.
A series of Zr-based UiO-n MOF materials ( n=66, 67, 68) have been studied for iodine capture. Gaseous iodine adsorption was collected kinetically from a home-made set-up allowing the continuous measurement of iodine content trapped within UiO-n compounds, with organic functionalities (−H, −CH 3, −Cl, −Br, −(OH) 2, −NO 2, −NH 2, (−NH 2) 2, −CH 2 NH 2) by in-situ UV-Vis spectroscopy. This study emphasizes the role of the amino groups attached to the aromatic rings of the ligands connecting the {Zr 6O 4(OH) 4} brick. In particular, the preferential interaction of iodine with lone-pair groups, such as amino functions, has been experimentally observed and is also based on DFT calculations. Indeed, higher iodine contents were systematically measured for amino-functionalized UiO-66 or UiO-67, compared to the pristine material (up to 1211 mg/g for UiO-67-(NH 2) 2). However, DFT calculations revealed the highest computed interaction energies for alkylamine groups (−CH 2NH 2) in UiO-67 (−128.5 kJ/mol for the octahedral cavity), and pointed out the influence of this specific functionality compared with that of an aromatic amine. The encapsulation of iodine within the pore system of UiO-n materials and their amino-derivatives has been analyzed by UV-Vis and Raman spectroscopy. We showed that a systematic conversion of molecular iodine (I 2) species into anionic I − ones, stabilized as I −⋅⋅⋅I 2 or I 3− complexes within the MOF cavities, occurs when I 2@UiO-n samples are left in ambient light. 相似文献
10.
Global warming challenges are fueling the demand to develop an efficient catalytic system for the reduction of CO 2, which would contribute significantly to the control of climate change. Herein, as-synthesized bismuthoxide-decorated graphene oxide (Bi 2O 3@GO) was used as an electro/thermal catalyst for CO 2 reduction. Bi 2O 3@GO is found to be distributed uniformly, as confirmed by scanning electron and transmission electron microscopic analysis. The X-ray diffraction (XRD) pattern shows that the Bi 2O 3 has a β-phase with 23.4 m 2 g −1 BET surface area. Significantly, the D and G bands from Raman spectroscopic analysis and their intensity ratio ( ID/ IG) reveal the increment in defective sites on GO after surface decoration. X-ray photoelectron spectroscopic (XPS) analysis shows clear signals for Bi, C, and O, along with their oxidation states. An ultra-low onset potential (−0.534 V vs. RHE) for the reduction of CO 2 on Bi 2O 3@GO is achieved. Furthermore, potential-dependent (−0.534, −0.734, and −0.934 vs. RHE) bulk electrolysis of CO 2 to formate provides Faradaic efficiencies (FE) of approximately 39.72, 61.48, and 83.00 %, respectively. Additionally, in time-dependent electrolysis at a potential of −0.934 versus RHE for 3 and 5 h, the observed FEs are around 84.20 % and 87.17 % respectively. This catalyst is also used for the thermal reduction of CO 2 to formate. It is shown that the thermal reduction provides a path for industrial applications, as this catalyst converts a large amount of CO 2 to formate (10 mm ). 相似文献
11.
Zirconium (IV) 4-amino, 3-hydroxy naphthalene sulfonate ion-exchanger has been synthesized by mixing equimolar solutions of zirconium oxychloride and ammonium hydroxide in molar ratio 1:1.66 to get a gelatinous material. To this were added varying amounts of 4-amino, 3-hydroxynaphthalene sulphonic acid (ANSA) with constant stiring in order to ensure a complete adsorption of organic molecules to the surface of the gel. The ion exchange material shows a dual character possessing both cation and anion exchange capacities. The former is attributed to the dissociation of strong sulphonic groups from ANSA and acidic sites of hydrous oxide gel, the later one is due to the formation of a positive charge on the nitrogen atom ; in addition, the material may have a sorption capacity. A preliminary investigation to characterize the material has been carried out which includes IR, TGA, DTA and X-ray diffraction. On the basis of distribution coefficients the separation of Hg +2 from Zn 2+, Al 2+, Ni 2+, Ce 4+, Mg 2+, Pb 2+, Mn 2+, Cu 2+, has been achieved. The decreasing sequence of Kd values for different anionic species are found to be PO 43− > Fe (CN) 63− > MnO 4− > VO 3− > AsO 43− > C 2O 42− and for halides Cl − > Br − > I −. 相似文献
12.
Crystalline {Cryptand(Na +)}[(COD)Rh ICl⋅Sn II(Pc 3−)] −⋅2C 6H 4Cl 2 ( 1 ) and {Cryptand(Cs +)}[(COD)Rh I⋅Sn II(Pc 4−)] −⋅C 6H 5CH 3 ( 2 ) complexes were obtained via the interaction of [Sn II(Pc 3−)] − and [Sn II(Pc 4−)] 2−, respectively, with organometallic {(COD)RhCl} 2 dimer (COD is 1,5-cyclooctadiene). Dissociation of {(COD)RhCl} 2 followed by the Rh−Sn binding is observed at the formation of 1 . Elimination of the chlorine atom at the rhodium atom is observed in 2 , and rhodium is additionally coordinated to the imine nitrogen atom of Pc 4−. The complexes contain mono- Pc⋅ 3− and doubly reduced Pc 4− species, respectively, that is supported by the data of XRD analysis as well as optical and magnetic properties of 1 and 2 . There is an alternation of C-N imine bonds in the macrocycles, which gradually increases with increasing negative charge on the macrocycle. The difference between shorter and longer bonds increases from 0.051 Å in Pc 3− to 0.075 Å in Pc 4−. The formation of 1 is accompanied by an essential blue shift of the Q-band of starting SnPc and the appearance of a new intense band at 1031 nm. The even stronger shift of the Q-band is observed in the spectrum of 2 , but the band in the near-IR range becomes weaker. The value of effective magnetic moment of 1 is 1.76 μB at 300 K corresponding the contribution of the Pc 3− radical trianions ( S=1/2). Only weak magnetic coupling with the Weise temperature of −3 K is observed in 1 due to weak π–π interaction between the macrocycles in the chains. Paramagnetic Pc 3− species additionally monitored by EPR spectroscopy show a strong temperature dependence of g-factor and linewidth of the EPR signal. Complex 2 is diamagnetic and EPR silent. 相似文献
13.
Co-crystallizing iodine with a simple dicationic salt (1,8-diammoniumoctane chloride) results in the clathration of the iodine (I 2) molecules inside trigonal and hexagonal helical channels of the crystal lattice with 72 wt % overall I 2 loading. The I 2 inside the bigger trigonal channel forms a I−I⋅⋅⋅I−I⋅⋅⋅I−I halogen-bonded infinite helical chain, while the I 2 in the smaller hexagonal channel is disordered. In both channels the I 2 interaction with the channel wall happens through I−I⋅⋅⋅Cl − halogen bonds. The helical channels in the crystal lattice are constructed via the strong charge-assisted H 2N +H⋅⋅⋅Cl − hydrogen bonds between the dications and the chloride anions. The structure shows a marked similarity with the well-known starch–I 2 system, and thus may provide insight for the yet unresolved structure of the I 2 in the helical starch channel. 相似文献
14.
BiOCl photocatalysis shows great promise for molecular oxygen activation and NO oxidation, but its selective transformation of NO to immobilized nitrate without toxic NO 2 emission is still a great challenge, because of uncontrollable reaction intermediates and pathways. In this study, we demonstrate that the introduction of triangle Cl−Ag 1−Cl sites on a Cl-terminated, (001) facet-exposed BiOCl can selectively promote one-electron activation of reactant molecular oxygen to intermediate superoxide radicals (⋅O 2−), and also shift the adsorption configuration of product NO 3− from the weak monodentate binding mode to a strong bidentate mode to avoid unfavorable photolysis. By simultaneously tuning intermediates and products, the Cl−Ag 1−Cl-landen BiOCl achieved >90 % NO conversion to favorable NO 3− of high selectivity (>97 %) in 10 min under visible light, with the undesired NO 2 concentration below 20 ppb. Both the activity and the selectivity of Cl−Ag 1−Cl sites surpass those of BiOCl surface sites (38 % NO conversion, 67 % NO 3− selectivity) or control O−Ag 1−O sites on a benchmark photocatalyst P25 (67 % NO conversion and 87 % NO 3− selectivity). This study develops new single-atom sites for the performance enhancement of semiconductor photocatalysts, and also provides a facile pathway to manipulate the reactive oxygen species production for efficient pollutant removal. 相似文献
15.
The specific conductivity and thermal electromotive force (EMF) coefficient of lanthanum cobaltite doped with strontium and nickel La0.9Sr0.1Co0.9Ni0.1O3−δ were measured over the temperature and pressure ranges 1023–1223 K and 10−6−1 atm. The oxide was found to exhibit metallic-type conductivity (800 Ω−1 cm−1 ≤ σ ≤ 1150 Ω−1 cm−1) and small positive thermal EMF coefficient values. A joint analysis of the thermodynamic characteristics of formation of point defects and external T and p
O
2 parameter dependences of conductivity and thermal EMF showed that charge was transferred in the oxide by small-radius polarons according to the hopping mechanism. The role of polarons was played by electrons Me
′Co
and holes Me
•Co
localized on 3d transition metals. The isothermal dependences of the concentrations and mobilities of charge carriers on the degree of oxygen nonstoichiometry of the oxide studied were calculated. 相似文献
16.
Synthesis and Crystal Structure of Bi 2ErO 4I Bi 2ErO 4I was prepared by solid‐state reaction of stoichiometric mixture of BiOI, Bi 2O 3 and Er 2O 3. Bi 2ErO 4I is a new compound and the first bismuth rare earth oxide iodide. The crystal structure was determined by the Rietveldmethod (P4/mmm, a = 3,8896(6) Å, c = 9,554(2) Å, Z = 1). In this structure [M 3O 4] +‐layers are interleaved by single I –‐layers. Er and Bi atoms of Bi 2ErO 4I are 8‐coordinated. The structure can be derived from the LiBi 3O 4Cl 2‐structure type. 相似文献
17.
Uranium and thorium hydrides are known as functional groups for ligand stabilized complexes and as isolated molecules under matrix isolation conditions. Here, the new molecular products of the reactions of laser-ablated U and Th atoms with HCl and with HBr, namely HUCl, HUBr and HThCl, HThBr, based on their mid and far infrared spectra in solid argon, are reported. The assignment of these species is based on the close agreement between observed and calculated vibrational frequencies. The H−U and U− 35Cl stretching modes of HUCl were observed at 1404.6 and 323.8 cm −1, respectively. Using DCl instead to form DUCl gives absorption bands at 1003.1 and 314.7 cm −1. The corresponding bands of HThCl are 1483.8 (H−Th) and 1058.0 (D −Th), as well as 340.3 and 335.8 cm −1 (Th− 35Cl), respectively. HUBr is observed at 1410.6 cm −1 and the BP86 computed shift from HUCl is 6.2 cm −1 in excellent agreement. The U−H stretching frequency increases from 1383.1 (HUF), 1404.6 (HUCl), 1410.6 (HUBr) to 1423.6 cm −1 (UH) as less electronic charge is removed from the U−H bond by the less electronegative substituent. These U−H stretching frequencies follow the Mayer bond orders calculated for the three HUX molecules. A similar trend is found for the Th counterparts. Additional absorptions are assigned to the H 2AnX 2 molecules (An=U, Th, X=Cl, Br) formed by the exothermic reaction of a second HX molecule with the above primary products. 相似文献
18.
The title salt, [Zn(C 2N 2H 8) 3] 2[CdI 4]I 2, conventionally abbreviated [Zn(en) 3] 2[CdI 4]I 2, where en is ethylenediamine, contains discrete [Zn(en) 3] 2+ cations and [CdI 4] 2− anions with distorted octahedral and nearly tetrahedral geometries, respectively, as well as uncoordinated I − ions. The cation and the free I − anion lie on twofold rotation axes and the [CdI 4] 2− anion lies on a axis in the space group I2 d. The structure exhibits numerous weak inter‐ionic hydrogen bonds of two types, viz. N—H⋯I −(free ion) and N—H⋯I([CdI 4] 2−), which support the resulting three‐dimensional framework. 相似文献
19.
Topological insulators (TIs) gained high interest due to their protected electronic surface states that allow dissipation-free electron and information transport. In consequence, TIs are recommended as materials for spintronics and quantum computing. Yet, the number of well-characterized TIs is rather limited. To contribute to this field of research, we focused on new bismuth-based subiodides and recently succeeded in synthesizing a new compound Bi 12Rh 3Sn 3I 9, which is structurally closely related to Bi 14Rh 3I 9 – a stable, layered material. In fact, Bi 14Rh 3I 9 is the first experimentally supported weak 3D TI. Both structures are composed of well-defined intermetallic layers of ∞2[(Bi 4Rh) 3I] 2+ with topologically protected electronic edge-states. The fundamental difference between Bi 14Rh 3I 9 and Bi 12Rh 3Sn 3I 9 lies in the composition and the arrangement of the anionic spacer. While the intermetallic 2D TI layers in Bi 14Rh 3I 9 are isolated by ∞1[Bi 2I 8] 2− chains, the isoelectronic substitution of bismuth(III) with tin(II) leads to ∞2[Sn 3I 8] 2− layers as anionic spacers. First transport experiments support the 2D character of this material class and revealed metallic conductivity. 相似文献
20.
The synthesis and structural characterization of 2‐(furan‐2‐yl)‐1‐(furan‐2‐ylmethyl)‐1 H‐benzimidazole [C 16H 12N 2O 2, (I)], 2‐(furan‐2‐yl)‐1‐(furan‐2‐ylmethyl)‐1 H‐benzimidazol‐3‐ium chloride monohydrate [C 16H 13N 2O 2+·Cl −·H 2O, (II)] and the hydrobromide salt 5,6‐dimethyl‐2‐(furan‐2‐yl)‐1‐(furan‐2‐ylmethyl)‐1 H‐benzimidazol‐3‐ium bromide [C 18H 17N 2O 2+·Br −, (III)] are described. Benzimidazole (I) displays two sets of aromatic interactions, each of which involves pairs of molecules in a head‐to‐tail arrangement. The first, denoted set (I a), exhibits both intermolecular C—H...π interactions between the 2‐(furan‐2‐yl) (abbreviated as Fn) and 1‐(furan‐2‐ylmethyl) (abbreviated as MeFn) substituents, and π–π interactions involving the Fn substituents between inversion‐center‐related molecules. The second, denoted set (I b), involves π–π interactions involving both the benzene ring (Bz) and the imidazole ring (Im) of benzimidazole. Hydrated salt (II) exhibits N—H...OH 2...Cl hydrogen bonding that results in chains of molecules parallel to the a axis. There is also a head‐to‐head aromatic stacking of the protonated benzimidazole cations in which the Bz and Im rings of one molecule interact with the Im and Fn rings of adjacent molecules in the chain. Salt (III) displays N—H...Br hydrogen bonding and π–π interactions involving inversion‐center‐related benzimidazole rings in a head‐to‐tail arrangement. In all of the π–π interactions observed, the interacting moieties are shifted with respect to each other along the major molecular axis. Basis set superposition energy‐corrected (counterpoise method) interaction energies were calculated for each interaction [DFT, M06‐2X/6‐31+G(d)] employing atomic coordinates obtained in the crystallographic analyses for heavy atoms and optimized H‐atom coordinates. The calculated interaction energies are −43.0, −39.8, −48.5, and −55.0 kJ mol −1 for (I a), (I b), (II), and (III), respectively. For (I a), the analysis was used to partition the interaction energies into the C—H...π and π–π components, which are 9.4 and 24.1 kJ mol −1, respectively. Energy‐minimized structures were used to determine the optimal interplanar spacing, the slip distance along the major molecular axis, and the slip distance along the minor molecular axis for 2‐(furan‐2‐yl)‐1 H‐benzimidazole. 相似文献
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