Metal Bromides Research Articles

Highly efficient and 100 % selectivity of CO generation via CO2 Photoreduction over a novel CsBr@CuBr2 Heterojunction

To address the global challenge posed by excessive carbon dioxide emissions, our research pioneers the transformation of CO2 into valuable hydrocarbon fuels. Central to this approach is the innovation of photocatalysts, engineered to exhibit exceptional photoresponse characteristics. In this research, the CsBr@CuBr2 photocatalyst was innovatively synthesized through a straightforward and effective one-pot method. The catalyst displayed remarkable efficacy, achieving a CO2 photoreduction rate of 201.47 μmol g−1 within just 4 h. The incorporation of CsBr into CuBr2 effectively captures excited-state electrons, thereby significantly enhancing charge separation efficiency. Utilizing in situ DRIFTS and DFT theoretical analysis, the experiment reveals the complex process of CO2 photoreduction to CO. The results of this experiment provide breakthrough insights for the systematic design of metal bromide heterostructures, which possess robust CO2 adsorption/activation potential and notable stability.

One‐Pot, One‐Step Synthesis of 2,5‐Diformylfuran from an Abundant Biomass Source and Low‐Cost Bromide Salts

AbstractThe process of synthesizing 2,5‐diformylfuran (DFF) from sucrose involves three sequential steps: hydrolyzing sucrose into fructose and glucose, dehydrating fructose into 5‐hydroxymethylfurfural (HMF), and subsequently converting HMF into DFF. In this study, various potassium salts and metal bromides, as well as carbohydrates and solvents, were screened for the production of DFF. It was found that KBr was the optimal catalyst for the one‐pot, one‐step conversion of sucrose to DFF. The influences of reaction time, temperature, reactant/solvent ratio, and reactant/catalyst ratio were also completely investigated for process optimization. HMF from the sucrose hydrolysis and fructose dehydration was oxidized thoroughly to DFF. The maximum DFF yield of 62.5 % was achieved after 6 h at 140 °C in dimethyl sulfoxide (DMSO) with sucrose/KBr weight ratio=5.75 and sucrose/DMSO weight ratio=0.104 as the catalyst in the absence of any additives. The large‐scale process was also tested, the main product was isolated by column chromatography and structurally characterized. By comparing the results of this study to previous ones, the process was proved to have benefits, including the utilization of accessible biomass material, available low‐cost catalyst, energy‐saving method, no oxidants or additives, short reaction time, and high DFF yield with 100 % HMF conversion.

Multiple Functions of l-Thioproline in the Synthesis of Chiral Metal Bromides Showing Second-Harmonic-Generation Responses.

Three new homochiral metal bromides, namely, (l-Htp)2Cu2Br4 (1), (l-Htp)(l-tp)CdBr3 (2), and (l-tp)2ZnBr2 (3), were prepared using l-thioproline as the chiral template. These compounds feature dimeric, chainlike, and monomeric structures. Their second-harmonic-generation (SHG) efficiencies are 0.1, 0.3, and 2.0 times that of KH2PO4, respectively. Density functional theory calculations were performed to reveal the origin of the SHG response of compound 3.

Salt‐melt synthesis of poly(heptazine imide) in binary alkali metal bromides for enhanced visible‐light photocatalytic hydrogen production

AbstractPoly(heptazine imide) (PHI), a semicrystalline version of carbon nitride photocatalyst based on heptazine units, has gained significant attention for solar H2 production benefiting from its advantages including molecular synthetic versatility, excellent physicochemical stability and suitable energy band structure to capture visible photons. Typically, PHI is obtained in salt‐melt synthesis in the presence of alkali metal chlorides. Herein, we examined the role of binary alkali metal bromides (LiBr/NaBr) with diverse compositions and melting points to rationally modulate the polymerization process, structure, and properties of PHI. Solid characterizations revealed that semicrystalline PHI with a condensed π‐conjugated system and rapid charge separation rates were obtained in the presence of LiBr/NaBr. Accordingly, the apparent quantum yield of hydrogen using the optimized PHI reaches up to 62.3% at 420 nm. The density functional theory calculation shows that the dehydrogenation of the ethylene glycol has a lower energy barrier than the dehydrogenation of the other alcohols from the thermodynamic point of view. This study holds great promise for rational modulation of the structure and properties of conjugated polymeric materials.

Crystal Structure and Optical Properties Characterization in Quasi-0D Lead-Free Bromide Crystals (C6H14N)3Bi2Br9·H2O and (C6H14N)3Sb3Br12.

Low dimensional organic inorganic metal halide materials have shown broadband emission and large Stokes shift, making them widely used in various fields and a promising candidate material. Here, the zero-dimensional lead-free bromide single crystals (C6H14N)3Bi2Br9·H2O (1) and (C6H14N)3Sb3Br12 (2) were synthesized. They crystallized in the monoclinic crystal system with the space group of P21 and P21/n, respectively. Through ultraviolet-visible-near-infrared (UV-vis-NIR) absorption analysis, the band gaps of (C6H14N)3Bi2Br9·H2O and (C6H14N)3Sb3Br12 are found to be 2.75 and 2.83 eV, respectively. Upon photoexcitation, (C6H14N)3Bi2Br9·H2O exhibit broad-band red emission peaking at 640 nm with a large Stokes shift of 180 nm and a lifetime of 2.94 ns, and the emission spectrum of (C6H14N)3Sb3Br12 are similar to those of (C6H14N)3Bi2Br9·H2O. This exclusive red emission is ascribed to the self-trapping exciton transition caused by lattice distortion, which is confirmed through both experiments and first-principles calculations. In addition, due to the polar space group structure and the large spin-orbit coupling (SOC) associated with the heavy elements of Bi and Br of crystal 1, an obvious Rashba effect was observed. The discovery of organic inorganic metal bromide material provides a critical foundation for uncovering the connection between 0D metal halide materials' structures and properties.

Charge transport comparison of FA, MA and Cs lead halide perovskite single crystals for radiation detection

We report a systematic comparison of the charge transport and radiation detection properties of inorganic and organic metal bromide single crystal perovskites. We studied the performance of Bridgman-grown CsPbBr3 single crystals, together with solution-grown FAPbBr3 and MAPbBr3 single crystals. Laser time of flight is used to measure the drift mobilities for all samples, and we report a maxium mobility value of 121 ± 10 cm V−1 s−1 for CsPbBr3. Alpha particle measurements were used to assess the mobility-lifetime products, with values recorded in the range of 2 × 10−4 cm2 V−1 to 1 × 10−3 cm2 V−1. Low temperature measurements showed an increase in bulk resistivity at temperatures down to 260 K, but no significant change to the drift mobilities. The overall performance of the Cs, FA and MA samples is compared and their potential for use in gamma spectroscopy measurements is discussed.

Facile Modification on Buried Interface for Highly Efficient and Stable FASn0.5Pb0.5I3 Perovskite Solar Cells with NiOx Hole‐Transport layers†

Comprehensive SummaryFormamidinium (FA)‐based Sn‐Pb perovskite solar cells (FAPb0.5Sn0.5I3 PSCs) with ideal bandgap and impressive thermal stability have caught enormous attention recently. However, it still suffers from the challenge of realizing high efficiency due to the surface imperfections of the transport materials and the energy‐level mismatch between functional contacts. Herein, it is demonstrated that the modification on buried interface with alkali metal salts is a viable strategy to alleviate these issues. We systematically investigate the role of three alkali metal bromide salts (NaBr, KBr, CsBr) by burying them between the NiOx hole transport layer (HTL) and the perovskite light‐absorbing layer, which can effectively passivate interface defects, improve energy‐level matching and release the internal residual strain in perovskite layers. The device with CsBr buffer layer exhibits the best power conversion efficiency (PCE) approaching 20%, which is one of the highest efficiencies for FA‐based Sn‐Pb PSCs employing NiOx HTLs. Impressively, the long‐term storage stability of the unencapsulated device is also greatly boosted. Our work provides an efficient strategy to prepare desired FA‐based ideal‐bandgap Sn‐Pb PSCs which could be applied in tandem solar cells.

A highly efficient, green, and straightforward approach for 2,5-diformylfuran synthesis from carbohydrates using carbonized sugarcane bagasse and KBr

2,5-Diformylfuran (DFF) is an important chemical that is utilized to synthesize several valuable chemicals. Direct preparation of DFF from plentiful and inexpensive carbohydrates in a one-pot approach is highly desired. Here, we report the development of a heterogeneous sulfonated amorphous carbon-derived sugarcane bagasse combined with KBr as a catalyst system to convert fructose to DFF in a short time and high yield in DMSO. Several reaction conditions, such as the effect of metal bromide, the effect of KBr and carbon-based solid acid catalyst loading, the effect of temperature, the effect of solvent, the effect of substrate, reusability test, and scale-up synthesis, have been investigated. The optimized yield of DFF was 90 ± 3% at 140 °C in DMSO solvent for 5 h. The approach has several outstanding features, including high chemo-selectivity, high yield, low cost, and recyclable catalyst.

Lead-free organic–inorganic azetidinium alternating metal cation bromide: [(CH2)3NH2]2AgBiBr6, a perovskite-related absorber

A new metal bromide perovskite derivative, azetidinium silver bismuth bromide is synthesized as a light-absorbing material.

Metal-free electrochemical regioselective aromatic C–H bromination of N,N-disubstituted anilines using propargyl bromide as the unprecedented bromine source

Source of a functional group is always an important factor in the chemical synthesis. Herein a new method for the highly regioselective monobromination of N,N-disubstituted anilines has been disclosed using propargyl bromide as the unconventional bromine source under electrochemical condition. Unlike other bromine sources, neither it requires any polarization nor any activator. The reaction smoothly proceeds at room temperature without using any metal catalyst or bromide salt. For unsubstituted anilines regioselective para-bromination was observed whereas both meta- and para-substituted anilines undergo predominant ortho-bromination leading to the corresponding N,N-disubstituted bromoanilines in good yields. Plausible mechanism has been depicted with supporting B3LYP/6-31G DFT calculations to explain the relative energy driven process.

Enrichment of heavy metals from spent printed circuit boards by microwave pyrolysis

This study reports the enrichment behaviors of heavy metals, including copper, tin, lead and zinc, in the process of microwave pyrolysis of spent printed circuit boards (SPCBs). The SPCB had good microwave absorptivity. Under the optimal conditions of microwave power of 700 W, pyrolysis temperature of 400 °C, dwell time of 5 min, N2 gas flow rate of 1.2 L/min, and load mass of 5 g, the yield of pyrolyzed SPCB was 79.16%. The contents of copper, tin, lead, and zinc in the pyrolyzed SPCB were increased to 28.52 wt%, 7.15 wt%, 1.31 wt%, and 1.13 wt%, respectively, with the corresponding retention percentages of 99.98%, 85.89%, 92.59% and 82.06%. The loss of metals was attributed to volatilization of the elements, which was affected by metal discharge due to excitation of electrons in the metals under microwave irradiation. Little copper loss was found because of the difficult reaction between copper and hydrogen bromide and the very high temperature required by the volatilization of copper. Tin, lead and zinc were mainly volatilized in the form of their metal bromides, including SnBr4, ZnBr2, and PbBr2. By controlling the pyrolysis conditions and metal discharge induced in the microwave field, the metals could be effectively enriched for subsequent treatment with high efficiency.

Synthesis and crystal structures of metal(I) bromide complexes containing 4-phenylthiosemicarbazide and triphenylphosphane ligands

Synthesis and crystal structures of metal(I) bromide complexes containing 4-phenylthiosemicarbazide and triphenylphosphane ligands

Bright and Efficient Pure Red Perovskite Nanocrystals Light‐Emitting Devices via In Situ Modification

AbstractAlthough light‐emitting devices (LEDs) based on metal halide perovskite nanocrystals (PNCs) developed rapidly in recent years, the luminance of pure red LEDs with the Rec. 2020 standard Commission Internationale de l'Eclairage 1931 color coordinates of (0.708, 0.292) cannot meet the requirement of outdoor display. Herein, a facile in situ modification strategy is proposed to prepare the efficiently luminescent CsPb(Br/I)3 PNCs, where metal bromides are used to create a halide‐rich environment and inhibit the formation of nonradiative surface defects. Synchronously, appropriately increased surface ligands improved the effective exciton confinement. Hence, the modified CsPb(Br/I)3 PNCs exhibited a high photoluminescence quantum yield of 92.0%. Additionally, the electrical conductivity is improved due to the increased hole mobility, and the Auger process is inhibited caused by balanced carrier mobilities. Consequently, LEDs based on the modified CsPb(Br/I)3 PNCs exhibited a maximum luminance of 11233 cd m−2 with the pure red color coordinate (0.704, 0.292) and a peak external quantum efficiency value of 13.2%. Furthermore, the luminance reached 5198 cd m−2 under the driving voltage of 4.4 V. This is the first study to realize a pure red PNC LED with high luminance under low bias, which can meet the requirement of outdoor display.

One-pot synthesis of sodium 3,4,5-triphenyl-1,2-diphospholide through direct functionalization of white phosphorus

Direct conversion of elemental white phosphorus (P4) to organophosphorus compounds is an attractive and challenging goal in sustainable phosphorus chemistry. We report here the one-pot reaction of P4, sodium metal and (1,2,3-triphenylcyclopropenyl)phosphonium bromides 1a,b to give exclusively sodium 3,4,5-triphenyl-1,2-diphospholide 2. An electrochemical method for following the conversion of 1,2,3-triphenylcyclopropenylphosphonium bromides to sodium 3,4,5-triphenyl-1,2-diphospholide is also presented.

Facile Fabrication of Highly Stable and Wavelength-Tunable Tin Based Perovskite Materials with Enhanced Quantum Yield via the Cation Transformation Reaction

Metal halide perovskites have attracted great attention for their superior light energy conversion applications. Herein, we demonstrated a facile synthesis of zero-dimensional Sn2+ perovskite Cs4-xMxSnBr6(M = K+ and Rb+) material through the cation transformation reaction at room temperature. Cs4SnBr6 NCs was mixed with pure metal bromide salts (KBr and RbBr) via the mechanochemical process to successfully synthesize Cs4-xMxSnBr6 perovskite where transformation of Cs to mixed Cs/Rb and mixed Cs/K was achieved. By substituting different cations, the bright fluorescence of the Cs4-xMxSnBr6 was tuned from dim green to greenish-cyan while achieving the photoluminescence (PL) quantum yield of ∼39%. The crystal structure of Sn based perovskite with the substitution of K+ or Rb+ cations was determined by X-ray diffraction (XRD). Moreover, the Cs4-xMxSnBr6 demonstrated superior air stability and exhibited a better photocatalytic activity for CO2 reduction reaction (CO2RR) with high selectivity of CH4 gas with a higher yield rate compared to the pristine Cs4SnBr6 NCs.

Near-unity blue-orange dual-emitting Mn-doped perovskite nanocrystals with metal alloying for efficient white light-emitting diodes

The tunable dual-color emitting Mn2+ doped CsPbCl3-xBrx nanocrystals (NCs) with near-unity photoluminescence quantum yield (PL QY) were synthesized through post-treatment of metal bromide at room temperature for fabrication of efficient warm white light-emitting diodes (WLEDs). Especially, the CdBr2 treated blue-orange emitting Mn doped NCs with various Mn/Pb molar feed ratios exhibit higher PL QY of 97% and longer Mn2+ PL lifetime of 0.9 ms. It is surprisingly found that the X-ray diffraction peak at 31.9° is almost not changed with increasing Br composition, meaning formation of metal alloying due to incorporation of amount of divalent cation in NCs. The strong and stable Mn2+ PL at temperature ranging from 80 K to 360 K are revealed and the temperature-dependent energy transfer efficiencies in Mn2+ doped CsPbCl1.5Br1.5 NCs are obtained. The enhancement mechanism of Mn2+ PL QY was attributed to improved energy transfer from exciton to Mn2+ d–d transition and suppressed defect state density after post-treatment. The efficient warm WLEDs with color rendering index of 90 and luminous efficacy of 92 lm/W at 10 mA were fabricated by combining blue-orange dual-emitting Mn2+ doped CsPbCl3-xBrx@SiO2 and green emissive CsPbBr3@SiO2 NCs with violet GaN chips.

Catalytic effect and mechanism of in-situ metals on pyrolysis of FR4 printed circuit boards: Insights from kinetics and products

Pyrolysis is a promising method for the recovery of waste printed circuit boards (WPCBs), but few researches have noticed the influence of in-situ metals. This study conducted a series of comparisons between metal-free leftover pieces (LP) and intact boards (IB), including pyrolysis characteristics, volatile emission, kinetics, and thermodynamic parameters. The thermo-gravimetry (TG) analyses indicated that both the samples presented predominant mass loss in narrow temperature intervals, and characteristic pyrolysis temperatures of IB were approximately 15 °C lower than those of LP. Dominant constituents in evolved gases were detected by Fourier-transform infrared spectrometry as CO2, phenol, bromophenol, ethers, ketones, and aldehydes, and metals accelerated the generation of light hydrocarbons and aromatic compounds. The activation energy and thermodynamic parameters were calculated and compared, and the results verified the presence of in-situ metals led to a lower energy barrier and higher reaction extent. Moreover, conversion behaviors of Cu, Fe, Sn, and Pb manifested the formation of metal bromides and implied the reduction of brominated volatiles. The obtained results confirmed the catalytic effect of in-situ metals on PCBs pyrolysis and their bromine fixation abilities. This study contributes to fundamental knowledge that can be used to guide the pyrolysis of WPCBs.

Polybromides of Transition Metal Chelates – Synthesis, Structure and Spectral Properties

AbstractFive new polybromide compounds containing tris‐chelates of 1,10‐phenanthroline and 2,2‐bipyridine as counter cations are described: [Mn(phen)3](Br3)2 (1), [Co(phen)3](Br3)3 (3) and [M(phen)3](Br3)(Br8)1/2 where, M=Fe (2), Cu(4) or Zn(5). All are obtained by self assembly in solution starting from divalent transition metal bromides and bromine along with the ligand. In the case of CoBr2, bromine acts as a tribromide precursor as well as oxidising agent. The Mn compound is isomorphous with the corresponding triodide and analogously contains one short and one normal trihalide ion. The Co compound contains one bent but symmetric Br3− ion. The three compounds containing the Z‐shaped octabromide ion are isostructural. While the cation in 1 has a crystallographically imposed C3 symmetry, the tris chelates in the other four compounds have near trigonal symmetry. Unusually, the trigonally compressed octahedral cation in 4 has six almost equal Cu−N bond distances. Attempts to prepare bpy analogs of 1 resulted in a new dibromo‐bridged compound [Mn2Br2(bpy)4](Br3)2 (6) and a dioxo‐bridged compound [Mn2O2(bpy)4](Br3)3 (7). The mixed valence cation in 7 formed by bromine oxidation of MnBr2, followed by disproportionation, is well known with other anions. All the paramagnetic compounds (1, 4, 6, 7) give resolved EPR spectra since the bulky anions help to magnetically isolate the cations. The unsymmetric dibromo bridges in 6 produce a net, albeit weak, ferromagnetic coupling between the two [Mn(bpy)2]2+ fragments. Raman as well as electronic spectra are reported for all compounds. Raman bands, though significantly different even for isostructural compounds, may be understood in terms of Br3− ions and Br2 molecules. All compounds give luminescence from phen and bpy both in solid and solution states, modulated by the coordinated metal ions.

The Surface Chemistry and Structure of Colloidal Lead Halide Perovskite Nanocrystals.

ConspectusSince the initial discovery of colloidal lead halide perovskite nanocrystals, there has been significant interest placed on these semiconductors because of their remarkable optoelectronic properties, including very high photoluminescence quantum yields, narrow size- and composition-tunable emission over a wide color gamut, defect tolerance, and suppressed blinking. These material attributes have made them attractive components for next-generation solar cells, light emitting diodes, low-threshold lasers, single photon emitters, and X-ray scintillators. While a great deal of research has gone into the various applications of colloidal lead halide perovskite nanocrystals, comparatively little work has focused on the fundamental surface chemistry of these materials. While the surface chemistry of colloidal semiconductor nanocrystals is generally affected by their particle morphology, surface stoichiometry, and organic ligands that contribute to the first coordination sphere of their surface atoms, these attributes are markedly different in lead halide perovskite nanocrystals because of their ionicity.In this Account, emerging work on the surface chemistry of lead halide perovskite nanocrystals is highlighted, with a particular focus placed on the most-studied composition of CsPbBr3. We begin with an in-depth exploration of the native surface chemistry of as-prepared, 0-D cuboidal CsPbBr3 nanocrystals, including an atomistic description of their surface termini, vacancies, and ionic bonding with ligands. We then proceed to discuss various post-synthetic surface treatments that have been developed to increase the photoluminescence quantum yields and stability of CsPbBr3 nanocrystals, including the use of tetraalkylammonium bromides, metal bromides, zwitterions, and phosphonic acids, and how these various ligands are known to bind to the nanocrystal surface. To underscore the effect of post-synthetic surface treatments on the application of these materials, we focus on lead halide perovskite nanocrystal-based light emitting diodes, and the positive effect of various surface treatments on external quantum efficiencies. We also discuss the current state-of-the-art in the surface chemistry of 1-D nanowires and 2-D nanoplatelets of CsPbBr3, which are more quantum confined than the corresponding cuboidal nanocrystals but also generally possess a higher defect density because of their increased surface area-to-volume ratios.

Multicomponent Organic Metal Halide Hybrid with White Emissions

AbstractZero‐dimensional (0D) organic metal halide hybrids, in which organic and metal halide ions cocrystallize to form neutral species, are a promising platform for the development of multifunctional crystalline materials. Herein we report the design, synthesis, and characterization of a ternary 0D organic metal halide hybrid, (HMTA)4PbMn0.69Sn0.31Br8, in which the organic cation N‐benzylhexamethylenetetrammonium (HMTA+, C13H19N4+) cocrystallizes with PbBr42−, MnBr42−, and SnBr42−. The wide band gap of the organic cation and distinct optical characteristics of the three metal bromide anions enabled the single‐crystalline “host–guest” system to exhibit emissions from multiple “guest” metal halide species simultaneously. The combination of these emissions led to near‐perfect white emission with a photoluminescence quantum efficiency of around 73 %. Owing to distinct excitations of the three metal halide species, warm‐ to cool‐white emissions could be generated by controlling the excitation wavelength.