HBr Solution Research Articles

Facile Synthesis of BiOBr/Bi2Sn2O7 Heterojunction Photocatalysts with Improved Photocatalytic Activities

BiOBr/Bi2Sn2O7 heterojunction photocatalysts were successfully synthesized by treating hydrothermal as‐prepared Bi2Sn2O7 nanoparticles with hydrobromic acid (HBr). Partial Bi2Sn2O7 nanoparticles reacted with HBr to form the sheet‐like BiOBr, and Bi2Sn2O7 nanoparticles distributed evenly on BiOBr sheets. BiOBr/Bi2Sn2O7 photocatalysts treated with different concentrations of HBr solution were successfully obtained, and their structures, morphologies, optical, and visible light photocatalytic properties were characterized by XRD, DRS, PL, SEM, and TEM. The experimental results showed that the BiOBr/Bi2Sn2O7 photocatalysts showed improved photocatalytic activity under visible light irradiation than pure Bi2Sn2O7. The sample treated with 0.08 mol/L HBr solution shows the best visible light photodegradation performance of rhodamine B. In addition, the active species and photocatalytic mechanism were discussed in detail.

Core-Shell Rhodium Sulfide Catalyst for HER/HOR in HBr Solution

Synthesis and characterization of high electrochemical surface area core-shell RhxSy catalysts for HER/HOR in HBr solution are discussed. Catalysts with RhxSy as shell and different percentage (5%, 10%, and 20%) platinum on carbon as core material are synthesized. Cyclic voltammetry was used to evaluate the Pt- equivalent mass specific ECSA and durability of these catalysts. The results show that the catalyst with core-shell structure has better performance compared to commercial catalyst (RhxSy/C catalyst from BASF). XRD, XPS and TEM were used to characterize the bulk and surface compositions and to confirm the core-shell structure of the catalysts, respectively.

ChemInform Abstract: A Bismuth‐Halide Double Perovskite with Long Carrier Recombination Lifetime for Photovoltaic Applications.

AbstractCs2AgBiBr6 is prepared by reaction of CsBr, BiBr3, and AgBr in 9 M HBr solution (110 °C, 2 h, 59% yield).

Growth Mechanism of Gold Nanorods in Binary Surfactant System

In order to reveal the growth mechanism of gold nanorods (GNRs) in a binary surfactant system, we synthesized various GNRs by changing the concentration of the surfactants, AgNO3 , and HBr in the growth solution. We found that the benzyldimethylhexadecylammoniumchloride surfactant had weak interaction with the gold ions, but it could reduce the membrane fluidity. In addition, we could dramatically decrease the cetyltrimethylammonium bromide concentration required for GNR growth by adding an HBr solution. Notably, Ag+ ions were necessary to break the symmetry of the seed crystals for GNR growth, but increasing the concentration of Ag+ and Br− ions caused a decrease in the template size.

Core-Shell Rhodium Sulfide As Catalyst for HER/HOR in HBr Solution

Electrical energy storage technologies are needed when significant fraction of intermittent renewable energy sources such as wind and solar are integrated into the electrical grids. The hydrogen-bromine (H2-Br2) reversible fuel cell system is one of the promising technologies because of its high round-trip conversion efficiency, high power density capability and low cost. In a hydrogen bromine fuel cell, while carbon surface can be for the bromine reactions, a noble metal such as platinum is needed for the hydrogen reactions. Since platinum is not stable in HBr/Br2 environment and HBr and Br2 are expected to cross from the bromine electrode to the hydrogen electrode during operation, a more durable and active catalysts is needed for the hydrogen reactions. RhxSy catalysts have been found to be stable in the HBr/Br2 environment and as active as platinum per active area.1, 2 Commercial RhxSy catalysts have large and broad particle sizes (12-40 nm) and consequently low mass specific active area (< 10 m2/g) for HOR. To address this problem, we explore the core-shell approach used by others 3 as a way to increase the mass specific area of these RhxSy catalysts. Figure 1 shows the mass specific active surface area (ECSA) of the core-shell and commercial RhxSy catalysts, and Table 1 shows a comparison of the mass specific ECSA and durability of commercial 20 wt. % Pt/C and commercial and core-shell RhxSy catalysts. These results show that the core shell RhxSy catalyst has much higher mass specific ECSA than commercial RhxSy catalyst and superior durability over platinum catalyst. This presentation will discuss the approach used to synthesis the core-shell RhxSy catalyst and the characteristics and performance of this catalyst. Figure 1. CV of core-shell and commercial RhxSy catalysts, measured in 1M H2SO4 at 10mV/s KU Core-Shell RhxSy/C 20 wt.% Pt/C Commercial RhxSy/C Time in 1M HBr (hr) m2/g % m2/g % m2/g % 0 61.4 100 127.3 100 7.8 100 24 60.2 98 82.7 65 48 58.4 97 42.2 51 Table 1. Durability in 1M HBr solution of Pt/C and commercial and core-shell RhxSy catalysts References Anna Ivanovskaya, Nirala Singh, Ru-Fen Liu, Haley Kreutzer, Jonas Baltrusaitis, Trung Van Nguyen, Horia Metiu, Eric W McFarland, “Transition Metal Sulfide Hydrogen Evolution Catalysts for Hydrobromic Acid Electrolysis,” Langmuir, 29(1), 480-492 (2013).Jahangir Masud, Trung Van Nguyen, Nirala Singh, Eric McFarland, Myles Ikenberry, Keith Hohn, Chun-Jern Pan, and Bing-Joe Hwang, “A RhxSy/C Catalyst for the Hydrogen Oxidation and Hydrogen Evolution Reactions in HBr,” J. Electrochem. Soc., 162 (4), F455-F462 (2015).Hee-Young Park, Tae-Yeol Jeon, Jong Hyun Jang, Sung Jong Yoo, Kug-Seung Lee, Yoon-Hwan Cho, Kwang-Hyun Choi, Yong-Hun Cho, Namgee Jung, Young-Hoon Chung and Yung-Eun Sunga, “Hydrogen Oxidation Reaction Activity of Sub-Monolayer Pt-Shell/Pd-Core Nanoparticles,” J. Electrochem. Soc., 160 (1), H62-H66 (2013). Acknowledgements The work presented herein was funded in part by the Advanced Research Projects Agency-Energy (ARPA-E), U.S. Department of Energy, under Award Number DE-AR0000262 and the National Science Foundation under Grant No. EFRI-1038234 and No. 1416874, as a sub-award from Proton Onsite. Figure 1

Determination of Bromine Stable Isotope Ratios from Saline Solutions by "Wet Plasma" MC-ICPMS Including a Comparison between High- and Low-Resolution Modes, and Three Introduction Systems.

We describe a novel method for measuring stable bromine isotope compositions in saline solutions such as seawater, brines, and formation waters. Bromine is extracted from the samples by ion exchange chromatography on anion exchange resin AG 1-X4 with NH4NO3 and measured by MC-ICP-MS in wet plasma conditions. Sample introduction through a small spray chamber provided good sensitivity and stability of the Br signal compared to direct injection (d-DIHEN) and desolvation (APEX). NH4NO3 media allowed fast (<3 min) washing of the system. Despite Ar2H(+) spectral interference on (81)Br(+), for the first time low-resolution mode (with appropriate tuning of Ar2H(+)/(81)Br(+) sensitivity) gave higher precision (81)Br/(79)Br measurements than high-resolution (HR), due to the narrowness of the (81)Br(+) plateau in HR mode and to slight mass drifting with time. Additionally, 1 μg Br is the lower amount needed for a triplicate determination of δ(81)Br by MC-ICP-MS, with reproducibility often < ± 0.1‰ (2 SD). Four HBr solutions were prepared by evaporation/condensation in order to obtain in-house reference solutions with 3‰ variations in δ(81)Br and to assess the reproducibility and accuracy of the method. Long-term (>3 years) reproducibility between ± 0.11 and ± 0.27‰ (2 SD) was obtained for the four HBr solutions, the international standard reference material NIST SRM 977 (δ(81)BrSMOB = -0.65 ± 1.1‰, 1 SD), and seawaters (synthetic and natural). The accuracy of the MC-ICP-MS method was validated by comparing the δ(81)Br obtained for these solutions with dual-inlet IRMS measurements on CH3Br gas. Finally, the method was successfully applied to 22 natural samples.

Trapping molecular bromine: a one-dimensional bromobismuthate complex with Br2 as a linker.

The reaction between solid (NMP)n{[BiBr4]}n (1) (NMP = N-methylpyridinium) and Br2, generated in situ in HBr solution, results in the formation of (NMP)3[Bi2Br9]·Br2 (2). In the structure of 2, dibromine molecules connect discrete binuclear [Bi2Br9](3-) anions into an extended network. Complex 2 is thermally stable (up to 150 °C).

Additive effects of steam addition and HBr doping for CaO-based sorbents for CO2 capture

Calcium looping is a developing CO2 capture and storage technology that employs the reversible carbonation of CaO (potentially derived from natural limestone). The CO2 uptake potential of CaO particles reduces upon repeated reaction, largely through loss of reactive surface area and densification of particles. Doping of particles has previously been found to reduce the rate of decay of CO2 uptake, as has the introduction of steam into calcination and carbonation stages of the reaction. Here, the synergistic effects of steam and doping, using an HBr solution, of 5 natural limestones have been investigated. The enhancement to the CO2 uptake was found to be additive, with CO2 uptake after 13 cycles found to be up to 3 times higher for HBr-doped limestones subjected to cycles of carbonation and calcination in the presence of 10% steam, in comparison to natural limestone cycled in the absence of steam. A qualitative discussion of kinetic data is also presented.

Determination of Os by isotope dilution-inductively coupled plasma-mass spectrometry with the combination of laser ablation to introduce chemically separated geological samples

A method was developed for the determination of trace Os in geological samples by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) with the combination of chemical separation and preconcentration. Samples are digested using aqua regia in Carius tubes, and the Os analyte is converted into volatile OsO4, which is distilled and absorbed with HBr. The HBr solution is concentrated for further Os purification using the microdistillation technique. The purified Os is dissolved in 10μl of 0.02% sucrose–0.005% H3PO4 solution and then evaporated on pieces of perfluoroalkoxy (PFA) film, resulting in the formation of a tiny object (<3×104μm2 superficial area). Using LA-ICP-MS measurements, the object can give Os signals at least 100 times higher than those provided by routine solution-ICP-MS while successfully avoiding the memory effect. The procedural blank and detection limit in the developed technique are 3.0pg and 1.8pg for Os, respectively when 1g of samples is taken. Reference materials (RM) are analyzed, and their Os concentrations obtained by isotope dilution are comparable to reference or literature values. Based on the individual RM results, the precision is estimated within the range of 0.6 to 9.4% relative standard deviation (RSD), revealing that this method is applicable to the determination of trace Os in geological samples.

Free-Standing Reduced Graphene Oxide Paper with High Electrical Conductivity

With high carrier mobility and low cost, reduced graphene oxide (RGO) shows bright prospects for use in the field of thermoelectric materials. To investigate the intrinsic thermoelectric properties of RGO sheets, we prepared RGO papers which were reduced by HBr solution for 5 min, 20 min, and 60 min, respectively. Thermogravimetry analysis (TGA) and Raman analysis showed that the conjugated carbon network of graphene oxide (GO) was restored during the reduction process and the thermal stability of the RGO papers was much better than that of GO paper. The RGO paper that was reduced for 60 min and then annealed in Ar/H2 atmosphere exhibited the highest electrical conductivity of 3.22 × 105 S/m at 160°C. As the reduction degree of the RGO paper deepens, the Seebeck coefficient gradually transforms from positive to negative, indicating that the conduction type of RGO paper can be controlled by regulating the reduction degree.

A RhxSy/C Catalyst for the Hydrogen Oxidation and Hydrogen Evolution Reactions in HBr

Rhodium sulfide (Rh2S3) on carbon support was synthesized by refluxing rhodium chloride with ammonium thiosulfate. Thermal treatment of Rh2S3 at high temperatures (600°C to 850°C) in presence of argon resulted in the transformation of Rh2S3 into Rh3S4, Rh17S15 and Rh which were characterized by TGA/DTA, XRD, EDX, and deconvolved XPS analyses. The catalyst particle size distribution ranged from 3 to 12 nm. Cyclic voltammetry and rotating disk electrode measurements were used to evaluate the catalytic activity for hydrogen oxidation and evolution reactions in H2SO4 and HBr solutions. The thermally treated catalysts show high activity for the hydrogen reactions. The exchange current densities (io) of the synthesized RhxSy catalysts in H2-saturated 1M H2SO4 and 1M HBr for HER and HOR were 0.9 mA/cm2 to 1.0 mA/cm2 and 0.8 to 0.9 mA/cm2, respectively. The lower io values obtained in 1M HBr solution compared to in H2SO4 might be due to the adsorption of Br− on the active surface. Stable electrochemical active surface area (ECSA) of RhxSy catalyst was obtained for CV scan limits between 0 V and 0.65 V vs. RHE. Scans with upper voltage limit beyond 0.65 V led to decreased and unreproducible ECSA measurements.

Planar CH3NH3PbBr3 hybrid solar cells with 10.4% power conversion efficiency, fabricated by controlled crystallization in the spin-coating process.

A power conversion efficiency of 10.4% is demonstrated in planar CH3 NH3 PbBr3 hybrid solar cells without hysteresis of the J-V curve, by way of controlled crystallization in the spin-coating process. The high efficiency is attributed to the formation of a dense CH3 NH3 PbBr3 thin film by the introduction of HBr solution because the HBr increases the solubility of the CH3 NH3 PbBr3 and forms a thinner CH3 NH3 PbBr3 layer with full surface coverage.

Enhancement in solar hydrogen generation efficiency using InGaN photoelectrode after surface roughening treatment with nano-sized Ni mask

A significant enhancement in solar hydrogen generation efficiency has been achieved by inductive coupled etching (ICP) surface roughening treatment using nano-sized nickel mask. As much as 7 times improvement of photocurrent is demonstrated in comparison with a planar one fabricated from the same parent wafer. Under identical illumination conditions in HBr solution, the incident photon conversion efficiency (IPCE) shows an enhancement with a factor of 3, which even exceed 54% at 400 nm wavelength. We believe the enhancement is attributed to several facts including improvement in absorption, reacting area, carrier localization and carrier lifetime.

Syntheses, Weak Interactions, and Crystal Structures of Two Tetrabromocuprate(II) Complexes Containing Benzyl Substituted Alkyl Pyridinium

Two tetrabromocuprate(II) complexes containing substituted benzyl alkyl pyridinium, [Bz-4-MePy]2[CuBr4] (1) and [Bz-4-EtPy]2[CuBr4] (2) ([Bz-4MePy]+ = (1-benzyl-4′-methylpyridinium) [Bz-4-EtPy]+ = 1-benzyl-4′-ethylpyridinium), were crystallized from methanol and dilute HBr solutions, and were determined by single crystal X-ray diffraction. Two complexes crystallize in the orthorhombic system with space group Pna21, and comprise two tortuous cations and one tetrahedral [CuBr4]2– anion. The [CuBr4]2– anions in two complexes form a linear chain by Br···Br interaction with the distance of 4.001 Å for 1 and 4.062 Å for 2, while the combination of C‒H···Br and C‒H···N weak hydrogen bonds, p···π and π···π, interactions consolidate the crystal packing and results in a 3D network structure.

Electrochemical bromination and oxidation of alkyl aromatic compounds by two-phase electrolysis

A simple, regioselective, environmentally clean and economical method for the preparation of side chain/ ring brominated aromatic compounds is reported in 70–98% yield by an electrochemical method using two phase electrolysis technique. Electrochemical reactions were carried out using aqueous 25–50 wt% sodium bromide containing catalytic amount (5 wt%) of hydrobromic acid as an aqueous phase and chloroform containing alkyl aromatic compounds as an organic phase, at a temperature of 0–30 °C in an undivided cell. The same two-phase electrolytic system can be used for the oxidation of benzylic alcohols to the corresponding benzaldehydes in 80–94% yield without over oxidation to carboxylic acids. The advantage of this very mild procedure is a room temperature reaction used with an undivided cell. Excellent conversions are observed. After completion of alcohol oxidation the electrolyte can be reused for a number of times, demonstrating “spent reagent” free electro organic reaction as an attractive one. In the case of side chain/ring bromination of alkyl aromatic compounds, the electrolyte can be reused after making up the concentration of the electrolyte with 47 wt% HBr solution. In some cases homogeneous electrolysis is applied, where the two-phase electrolysis did not work. Styrene epoxidation and α-bromination of ketones underwent homogeneous electrolysis at room temperature without any catalyst. The reaction was performed in CH3CN-water (3: 2) using equimolar amount of NaBr as an electrolyte to get 68% of styrene epoxide. Use of an ionic liquid 1-butyl 3-methyl imidazolium bromide (Bmim) Br, instead of NaBr improved the yield and current efficiency of styrene epoxide to 86%.

Application of Modified Magnetite Nanoparticles as a New Sorbent for Separation/Preconcentration of Mercury(II) Trace Amounts and its Determination by Cold Vapor Atomic Absorption Spectrometry

A new, simple, fast and reliable method has been developed to separation/preconcentration of trace amounts of mercury ions using dithizone/sodium dodecyl sulfate-immobilized on alumina-coated magnetite nanoparticles (DTZ/SDS-ACMNPs) and its determination by cold vapor atomic absorption spectrometry (CVAAS). This method avoided the time-consuming column-passing process of loading large volume samples in traditional solid phase extraction (SPE) through the rapid isolation of DTZ/SDS- ACMNPs with an adscititious magnet. Under the optimal experimental conditions, the enrichment factor, detection limit, linear range and relative standard deviation (RSD) of Hg(II) ions were 250 (for 500 mL of sample solution), 0.058 µg mL -1 , 0.2 - 80.0 µg mL -1 and 3.55 % (for 5.0 µg mL -1 , n = 10), respectively. The adsorbed mercury ions were quantitatively eluted by 2.0 mL of 0.4 mol L -1 HBr solution. The pre- sented procedure was successfully applied for determination of mercury content in the different samples of water and blood.

Synthesis and properties of compounds of formamidindium disulfide with d-element tetrahalide anions

Products of reactions of salts of d elements with formamidine disulfide dihydrochloride (FDSH2Cl2) in concentrated HCl and HBr solutions were synthesized and characterized. The following compounds were obtained: FDSH2[CuCl4] · H2O, FDSH2[CoCl4], FDSH2[ZnCl4], FDSH2[HgCl4], and FDSH2[HgBr4]. The identity of these compounds was confirmed by X-ray diffraction; their compositions were derived from the results of chemical analysis and thermal analysis. The IR and Raman scattering spectra of the compounds indicate the presence therein of FDSH22+ cation. It was established that FDSH22+ transforms into formamidindium trisulfide cation (NH2)2C-S-S-S-C(NH2)22+ upon storage in air in hydrochloric acid solution.

Acid-Catalyzed Hydrolysis of Some N,N-Dibenzylalkanesulfinamides in 50% Acetonitrile–Water

The hydrolysis of some N,N-dibenzylalkanesulfinamides (RSONH(CH2Ph)2; 1, R = Me; 2, R = iPr; 3, R = tBu; 4, R = 1-adamantyl) has been studied in 50% (v:v) acetonitrile–water solutions of hydrobromic and hydrochloric acids, mainly at 44.8 °C, using ultraviolet (UV) spectrophotometry to determine pseudo first-order rate constants. The compounds were found to hydrolyze by concurrent bimolecular neutral, acid-catalyzed, and acid-dependent nucleophilic (halide ion) catalysis pathways. The last-named is predominant in reactions in HBr solutions, but in HCl solutions, the acid-catalyzed pathway is predominant. The results indicate that both steric and electronic effects are important in these reactions. There appears to be no mechanistic switchover in the series 1→4.

Rapid determination of ultra-trace amounts of acrylamide contaminant in water samples using dispersive liquid–liquid microextraction coupled to gas chromatography-electron capture detector

The objective of the present study was to develop and validate a rapid, highly sensitive, and reliable extraction method to determine acrylamide in water samples. The method was based on the derivatisation of the acrylamide in the presence of KBr, HBr and saturated Br2 solution into 2,3-dibromopropionamide and dispersive liquid–liquid microextraction (DLLME) followed by gas chromatography–electron capture detection (GC–ECD) of the analyte. Different parameters that affect the DLLME process such as types and volumes of disperser solvent, ionic strength of aqueous solution and extraction time were investigated and optimised. Under optimal conditions, excellent linearity was obtained between concentration of acrylamide and the response of ECD with correlation of determination (R2) of 0.9999. The precision of the method, which was determined by calculating the relative standard deviations (RSD) of the at least three replicate measurements, was 3.6%. The method presented in this study is sensitive enough for the determination of acrylamide in different water samples with the limit of detection (LOD) value of 1 ng L−1. The mean percentage recoveries exceeded 91% for all of spiking levels in the real water samples. The results obtained from DLLME method are validated by EPA method 8032A.

3-Methyl-1,2,3,4,5,6,1′,2′,3′,4′-decahydrospiro[benz[f]isoquinoline-1,2′-naphthalen]-1′-one

The title compound, C23H23NO, is the product of a tandem transformation of the double Mannich base bis­(1-oxo-1,2,3,4-tertrahydro-2-naphtho­ylmeth­yl)amine hydro­chloride in HBr solution upon heating. The tetra­hydro­pyridine ring has a non-symmetrical half-chair conformation, whereas the cyclo­hexa­diene and cyclo­hexene rings adopt non-symmetrical half-boat conformations. The dihedral angle between the planes of the terminal benzene rings is 62.85 (6)°. The N atom has a trigonal–pyramidal geometry [sum of the bond angles = 332.4 (3)°]. In the crystal, mol­ecules form [001] chains via weak non-classical C—H⋯N hydrogen bonds. The chains are stacked along the b axis.