Diffuse Reflectance Research Articles

A MOF@MOF S-scheme Heterojunction with Lewis Acid-Base Sites Synergistically Boosts Cocatalyst-Free CO2 Cycloaddition.

The photocatalytic cycloaddition reaction between CO2 and epoxide is one of the most promising green routes for CO2 utilization, for which high performance photocatalysts are intensely desired. Herein, we have constructed an S-scheme heterojunction of MIL-125@ZIF-67 modified by amino groups, which achieves a cyclic carbonate yield of as high as 99 % without employing any co-catalyst, outperforming the previously reported photocatalysts. In-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and in-situ electron paramagnetic resonance (EPR) spectroscopy reveal the important role of photogenerated electron migration from Lewis acid (Co) sites to the O atom of epoxide in triggering its ring-opening (the rate-determining step of CO2 cycloaddition reaction) under the assistance of photogenerated hole. Synergistically and concurrently, the Lewis base (amino groups) sites activate CO2 to CO2*, facilitating the following CO2 cycloaddition. Such a synergistic effect provides a most favorable approach to design efficient heterogeneous photocatalysts with dual/multiple-active sites for CO2 cycloaddition reaction.

Cerium-infused tungstate nanocrystals: Illuminating the future of solid-state lighting

Rare earth based luminescent materials have emerged as a focal point of the scientific investigation owing to their remarkable optical behaviour and potential applications. An effort has been made to develop a series of Ce3+ doped CaWO4 nano-phosphors using an ethylene-glycol assisted reflux route. The detailed structural and morphological properties have been examined through various analytical techniques. The +3-oxidation state of the activator ion Ce has been verified through the XPS study. The change in optical band gap due to the substitution is well discussed using diffuse reflectance spectroscopy. In Photoluminescence study, a broad emission centred at 465 nm is observed due to the 5D3/2→2FJ transitions (J = 7/2 and 5/2) and a significant enhancement in the emission peak is obtained for the optimized phosphor. Concentration quenching phenomenon, observed after 3 mol% of Ce3+ is mainly mediated by the electric multipole-multipole type interaction. The CIE diagram indicates the tuning of emission colour from blue to white region and the emission near white region for the optimized phosphor is further authenticated by its low colour purity value (43 %). The effective tunability of photo-physical properties and colorimetric parameters suggest the applicability of the optimized nano-phosphor in solid state lighting especially for outdoor illumination.

Energy trapping to substitutional and charge compensation defects in persistent luminescent BaAl2O4:Tb3+

The holistic approach of the photoluminescence (PL), thermoluminescence (TL), and persistent luminescence properties at room temperature of BaAl2O4:Tb3+ were investigated in detail using a wide range of techniques. Materials were obtained using a solution combustion synthesis. The x-ray powder diffraction patterns of nondoped and Tb3+ doped BaAl2O4 indicated the hexagonal phase, and a Tb4O7 solid solution was observed at 4 and 5 mol% Tb doped aluminate. X-ray photoelectron spectroscopy revealed that Ba occupied one site and that Tb ions occupied this site as Tb3+ as well as TbIV. PL emission in blue, green, and red was observed under an excitation at 228 nm, that originated from the interconfigurational 4f8–4f75d1 transitions of Tb3+. Time-of-flight secondary ion mass spectroscopy, UV–vis diffuse reflectance, and PL revealed the presence of a Cr3+ impurity. The 0.5 mol% Tb3+ doped BaAl2O4 exhibited a strong TL band at 354, 437 and 598 K, which were attributed to the traps formed by Tb3+ doping and subsequent O2− charge compensation. A persistent luminescence mechanism was constructed for the Tb3+ doped BaAl2O4. After the energy was stored in thermally liberated Tb3+ in the Ba2+ substitution sites and charge compensation defects, the Tb3+ was the source of the continuous luminescence.

Electronic effect in bromide-modified noble metal catalysts promotes highly stable and selective hydrogenation

Halides with strong affiliation to metals are traditionally viewed as positions in heterogeneous catalysis. This study introduces a method to enhance the selective hydrogenation performance of noble metal nanoparticle catalysts (Pd, Pt, and Rh hosted on N-doped carbon, SiO2, and Al2O3) by gas-phase bromination with 1-bromooctane. Brominated Pd catalysts, particularly those supported on N-doped carbon, show significant improvements in total butene selectivity and stability in butadiene hydrogenation reactions, displaying >97.5 % selectivity to total butenes at complete conversion with 50 h stable performance even at excessive H2 (H2:butadiene = 50) and a high temperature of 473 K. Comprehensive characterizations coupled with density functional theory calculations reveal that bromide species enhance selective hydrogenation by preferentially adsorbing at stepped Pd sites, altering reaction kinetics and preventing over-hydrogenation. Bromination influences reactant and intermediate adsorption, leading to increased competitive adsorption compared to pristine catalysts. Chemisorption studies on butadiene and 1-butene support altered kinetic behaviors post-bromination. X-ray photoelectron spectroscopy analysis demonstrate an increase in surface Pdδ+ species, owing to the electron-pulling character of nearby adsorbed bromide. In situ diffuse reflection infrared Fourier transform spectroscopy with CO probe molecules confirms Br species adsorption at unsaturated Pd sites. Overall, the study provides an effective approach to tuning the electronic properties of metal catalysts and highlights the positive impact of bromination on improving the hydrogenation performance.

The enhanced SO2 resistance of Fe-Ti catalyst by W/SO42− co-modification for NH3-SCR: A combined experimental and DFT study

It remains a great challenge to improve the low-temperature SO2 resistance of catalysts applied for selective catalytic reduction of NOx with NH3 (NH3-SCR). This work develops an outstanding SO2-tolerant Fe-Ti (FT) catalyst by W/SO42− co-modification via a sol–gel method using Fe(NO3)3·9H2O, tetrabutyl titanate, ammonium tungstate and thiourea as raw materials. The physicochemical characterizations, in-situ diffuse reflectance infrared Fourier transform (DRIFT) measurements and density functional theory (DFT) calculations were combined to reveal the underlying mechanisms. Although W doping can effectively enhance the surface acidity, NH3 adsorption on Lewis acid sites can still be restrained by competitive adsorption of SO2, whereas SO42− modification can enhance the adsorption stability of NH3 without being affected by SO2. Simultaneously, the NO adsorption ability on Fe sites can be significantly enhanced by W/SO42− co-modification. Furthermore, the W doping or SO42− modification can induce conversion of Fe3+ to Fe2+ to affect the redox property of Fe species. A proper amount of Fe2+ suppressed the oxidizability of FT catalyst to inhibit NH3 overoxidation to enhance N2 selectivity, and created more oxygen vacancies to generate larger amount of chemisorbed oxygen to facilitate NH3 dehydrogenation and NO oxidation. More importantly, the inhibition effect of SO2 adsorption on Fe sites was strengthened by W/SO42− co-modification. Consequently, the W/SO42− co-modified FT catalyst exhibited high activity with >90 % of NO conversion and >95 % of N2 selectivity within a broad window of 275–450 °C and possessed superior SO2 + H2O tolerance at 275 °C.

Sonochemical preparation of powerful S-scheme Zr(HPO4)2/g-C3N4 heterojunction for photocatalytic degradation of rhodamine B under natural solar radiations

An effective Zr(HPO4)2/g-C3N4 S-scheme heterojunction was synthesized by sonochemical coupling of Zr(HPO4)2 nanoparticles as an oxidative photocatalyst [EVB = +3.0 eV] with g-C3N4 nanosheets as an effective reductive photocatalyst [ECB = −1.25 eV] for photocatalytic degradation of rhodamine B dye under natural solar radiation of 1000 W power. The physicochemical properties of the as-synthesized heterojunctions were investigated by X-ray diffraction [XRD], N2-adsorption-desorption isotherm, diffuse reflectance spectrum [DRS], photoluminescence [PL], scanning electron microscope [SEM], X-ray photoelectron spectroscope [XPS], and high resolution transmission electron microscope [HRTEM]. The experimental results implied the agglomeration of Zr(HPO4)2 nanoparticles on g-C3N4 sheets which reduced the specific surface area of the solid specimen from 88 to 21 m2/g. The significant increase in the photocatalytic degradation rate of RhB dye with introducing Zr(HPO4)2 nanoparticles implied that Zr(HPO4)2 plays a crucial role in reducing the band gap energy and remarkable increasing in the rate of electron-hole separation. The photocatalytic experiments implied that incorporation of 5 wt% Zr(HPO4)2 on g-C3N4 sheets destroyed 98 % of RhB dye during 3 h of light illumination with pseudo-first-order rate of 0.048 min−1. The remarkable enhancement in the photocatalytic performance of Zr(HPO4)2/g-C3N4 heterojunctions was ascribed to successful generation of an effective S-scheme heterojunction with strong redox power, utilizing of both hydroxyl and superoxide radicals in the degradation process and limiting the electron-hole recombination rate. Based on scavenger experiments and terephthalic acid PL analysis, the S-scheme pathway was chosen as the proposed mechanism for photocatalytic charge transfer. The as-synthesized Zr(HPO4)2/g-C3N4 heterojunction with exceptional redox power is considered a novel candidate for destructing organic pollutants that exist in industrial wastewater.

Nanostructural Influence on Optical and Thermal Properties of Butterfly Wing Scales Across Forest Vertical Strata.

Butterfly wing scales feature complex nanostructures that influence wing coloration and various mechanical and optical properties. This configuration plays a key role in ecological interactions, flight conditions, and thermoregulation, facilitated by interactions with environmental electromagnetic energy. In tropical forests, butterflies occupy distinct vertical habitats, experiencing significant light and temperature variations. While wing nanostructures have been widely studied, their variation across different vertical flight preferences remains underexplored. This study investigates the wing nanostructures of 12 tropical butterfly species from the Nymphalidae family, focusing on their optical, morphological, and thermal properties across different forest strata. We analyzed the optical response through diffuse reflectance in the UV, Vis, and NIR ranges, correlating these findings with nanostructural configuration and thermal stability using thermogravimetric analysis (TGA). Our results reveal a significant correlation between flight stratification and wing optical responses, alongside distinct nanostructural features within each stratum. This study demonstrates the variability in butterfly wing nanostructures along the vertical stratification of the forest to cope with environmental conditions, raising new questions for future research on eco-evolutionary flight and thermal adaptations. Additionally, this underscores the importance of understanding how these structural adaptations influence butterfly interactions with their environment and their evolutionary success across different forest strata.

New Ceramic Material Y2‐xVxO3+x – Mechanochemical Synthesis and Some Physicochemical Properties

AbstractPotential applications of known compounds from the V2O‐Y2O3 system, i. e. YVO4, Y8V2O17 and Y10V2O20, were the inspiration to undertake research, the main goal of which was to determine whether unknown phases of the solid solution type are formed in this system. Solid solutions are still sought‐after phases because their properties depend on their chemical composition. In this work it was experimentally demonstrated that a new substitute solid solution with the formula Y2‐xVxO3+x (0.00<×<0.60) is formed from mixtures of V2O5 with Y2O3 as a result of mechanochemical synthesis. Its properties were examined by using, i.a. XRD (X‐ray diffraction) and UV‐Vis‐DRS (ultraviolet‐visible light spectroscopy with diffusion reflectance) methods. It was found among other things, that it crystallizes in a regular system, exhibits a Y2O3 structure and is thermally stable up to at least 800 °C (for x=0.40). Moreover, the estimated value of the band gap width indicated that the solid solution Y2‐xVxO3+x belongs to the class of semiconductors. The study of dielectric properties of new phase was performed by means of broadband dielectric spectroscopy. The obtained measurement data showed the presence of relaxation type dielectric mechanisms. The thermally activation energies of the relaxation processes related to the electric conductivity were calculated.

Structural, optical, and thermal traits of Sm³⁺-doped SrB₂O₄ phosphors for solid-state lighting applications

We synthesized Sm³⁺-doped SrB₂O₄ phosphors through a solid-state reaction method, varying the Sm³⁺ doping concentrations. Structural and morphological characteristics of material were investigated using Fourier-transform infrared spectroscopy (FTIR), X-Ray Diffraction (XRD) and scanning electron microscopy (SEM). Optical transitions were analyzed by recording the diffuse reflectance spectroscopy, while photoluminescent (PL) spectra were used to evaluate luminescence properties. The PL spectra revealed a strong orange emission at 598 nm under 402 nm excitation. The optimal Sm³⁺ doping concentration was determined to be 0.02 mol, beyond which concentration quenching occurred. This quenching is attributed to exchange-type interactions, which facilitate non-radiative energy relaxation. The CIE color chromaticity coordinates of all the synthesized phosphors fell within the orange region of the chromaticity diagram. Temperature dependent photoluminescence revealed lower activation energy and phonon energy. Thermal quenching temperature was calculated which is inline with commercially available LEDs. All of these results indicate the candidature of SrB2O4 phosphor doped with Sm3+ ions for solid state lighting and optical thermal sensing applications.

Vibrational, optical, electronic and electrocatalytic properties of SrCuSi4O10 ceramic

This research reports the synthesis of powdered SrCuSi4O10 ceramic powder, obtained through a solid-state chemical reaction methodology. The sample was characterized using X-ray powder diffraction (XRPD), Raman and Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), reflectance (R), electron paramagnetic resonance spectrum (EPR), lattice dynamic calculations, electronic and electrocatalytic properties analyses. The X-ray analysis showed that crystalline structure of SrCuSi4O10 compound belongs to a tetragonal system with the P4/ncc space group, containing four formulas per unit cell (Z = 4). The SEM micrographs present a morphology of layered microplates with some irregularity in size and shapes. UV–vis diffuse reflectance spectra show three intense reflection regions. Regarding the vibrational properties, the theoretical calculation was performed using a rigid ion model in order to assign the experimental Raman and IR modes. Additionally, electronic properties calculations were carried out using Density Functional Theory (DFT). Finally, the hydrogen evolution reaction (HER) performance of the SrCuSi4O10 electrocatalyst was evaluated.

Photodegradation of Polyethersulfone (PES), Polyvinylidene Fluoride (PVDF) and Polymethyl Methacrylate (PMMA) Microplastics via a Metal Organic Framework Namely ZIF-8/ZnO/C

The aim of this study was to photodegrade the Polyethersulfone (PES), Polyvinylidene fluoride (PVDF) and Polymethyl methacrylate (PMMA) microplastics using Zeolitic imidazolate framework-8/Zinc oxide/Carbon (ZIF-8/ZnO/C) nanocomposite generated under laboratory conditions. The produced nanocomposite was analysed using X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Photo Spectroscopy (XPS), Scanning Electron Microscope (SEM), Diffuse reflectance UV-vis spectra (DRS) and Electron Spin Resonance (ESR) analyses. The maximum PES, PVDF and PPMA photodegradation yields were 99%, 98%, and 96%, respectively, at 1 mg/l ZIF-8/ZnO/C nanocomposites (NCs) concentration, 1000 mg/l microplastics concentration, at pH = 10.0, at a temperature and photodegradation time of 40°C and 20 min, under oxic conditions at a sunlight intensity of 80 W/m<sup>2</sup> and a photon yield of 16. The XRD analysis showed the generation of ZIF-8/ZnO/C, while the FTIR analysis indicated the ZnO, C, and ZIF-8.

Photocatalysis of Adsorbed Catechol on Degussa P25 TiO2 at the Air-Solid Interface.

Semiconductor photocatalysis with commercial TiO2 (Degussa P25) has shown significant potential in water treatment of organic pollutants. However, the photoinduced reactions of adsorbed catechol, a phenolic air pollutant from biomass burning and combustion emissions, at the air-solid interface of TiO2 remain unexplored. Herein we examine the photocatalytic decay of catechol in the presence of water vapor, which acts as an electron acceptor. Experiments under variable cut-off wavelengths of irradiation (λcut-off ≥ 320, 400, and 515 nm) distinguish the mechanistic contribution of a ligand-to-metal charge-transfer (LMCT) complex of surface chemisorbed catechol on TiO2. The LMCT complex injects electrons into the conduction band of TiO2 from the highest occupied molecular orbital of catechol by visible light (≥2.11 eV) excitation. The deconvolution of diffuse reflectance UV-visible spectral bands from LMCT complexes of TiO2 with catechol, o-semiquinone radical, and quinone and the quantification of the evolving gaseous products follow a consecutive kinetic model. CO2(g) and CO(g) final oxidation products are monitored by gas chromatography and Fourier-transform infrared spectroscopy. The apparent quantum efficiency at variable λcut-off are determined for reactant loss (Φ- TiO2/catechol = 0.79 ± 0.19) and product growth ΦCO2 = 0.76 ± 0.08). Spectroscopic and electrochemical measurements reveal the energy band diagram for the LMCT of TiO2/catechol. Two photocatalytic mechanisms are analyzed based on chemical transformations and environmental relevance.

Investigation of structural, optical, dielectric, and electrical properties of NaMn4(PO4)3 (NMP) with fillowite-type structure

We synthesized sodium tetra manganese phosphate, NaMn4(PO4)3, by a solid-state method at a temperature of 900 °C for a duration of 10 h. The application of Rietveld analysis to the PXRD patterns revealed that the sample synthesized show the small amount of the secondary phase (Mn2P2O7). The NaMn4(PO4)3 compound belongs to the trigonal system, namely the R-3 space group. The powder's morphology was examined using scanning electron microscopy (SEM), which revealed an average grain size of approximately 7 μm. The powder underwent elemental analysis using energy dispersive X-ray spectroscopy (EDS), which confirmed the uniformity of the sample. Raman and Fourier transform infrared (FTIR) spectroscopies reveal the distinctive spectral peaks associated with P-O bonds in the (PO4)3- functional group. The optical bandgap energy of 1.57 eV was calculated using the diffuse reflectance technique with the Kubelka-Munk function and Tauc's relation. The chromatic coordinates of NaMn₄(PO₄)₃ suggest that the sample can generate blue-purple light, rendering it appropriate as a red phosphor in white light-emitting diodes (LEDs). Integrating this red emission with blue and green light from additional LED components might enhance the overall color quality and efficiency of white light generation. The dielectric properties of NMP exhibited characteristics that were consistent with ionic conductivity. The Nyquist plot displayed a conspicuous semicircle, indicating the presence of a dominant singular process, most probably linked to the bulk grain. The material demonstrates a significant degree of conductivity, with a measured value of around 3.72 × 10–4 S·cm-1 at a temperature of 300 °C.

Synergistic Effect of NiAl-Layered Double Hydroxide and Cu-MOF for the Enhanced Photocatalytic Degradation of Methyl Orange and Antibacterial Properties

This study synthesized NiAl-layered double hydroxide (LDH)/Cu-MOF photocatalyst using a simple impregnation method involving NiAl-LDH and Cu-MOF. The successful synthesis was confirmed through Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), zeta potential measurements, thermogravimetric analysis (TGA), ultraviolet diffuse reflectance spectroscopy (UV-DRS), N2 adsorption at −196 °C, and electrochemical impedance spectroscopy (EIS). Photocatalysts based on NiAl-LDH, Cu-MOF, and NiAl-LDH/Cu-MOF were used to remove methyl orange (MO) dye from contaminated water. The impact of various factors, including pH, dye concentration, and photocatalyst amount, on MO degradation efficiency was assessed. FTIR analysis was conducted both before and after dye degradation. The optimal degradation conditions were a photocatalyst dose of 25 mg and a pH of 3. Kinetic studies indicated that the degradation of MO dye onto NiAl-LDH/Cu-MOF followed a pseudo-first-order and an L–H or Langmuir–Hinshelwood model. The value of R2 = 0.94 confirms the validity of pseudo-first-order and Langmuir–Hinshelwood (L–H) kinetic models for the photocatalytic degradation of MO dye. This study highlights the importance of developing novel photocatalysts with improved degradation efficiency to protect the water environment. Antibacterial activity was also performed with antibacterial sensibility testing by disk diffusion to determine minimal inhibitory and bactericidal concentrations. In short, NiAl-LDH/Cu-MOF can be helpful for various biomedical and industrial applications.

Iron as a precursor of aggregation and vector of organic carbon to sediments in a boreal lake

AbstractWhile organic matter (OM) interactions in the water column prevent iron (Fe) precipitation and sedimentation, Fe also acts as a precursor of aggregation and a vector of OM to sediments. This study aims to characterize Fe–OM interactions to understand the role of Fe in promoting aggregation and transport of OM. Samples of Fe and OM were collected from water, settling material, and sediment along a gradient starting from the inlet and continuing offshore within a boreal lake. Fe speciation was determined using X-ray absorption spectroscopy (XAS), and the chemical composition of OM was assessed using Diffuse reflectance infrared Fourier transform spectroscopy (DRIFT IR) and Nuclear magnetic resonance spectroscopy (NMR). The results show a decrease in Fe and OM concentrations in the water column with increasing distance from the inlet. Winter sampling revealed a shift in Fe speciation from dominance of organically complexed Fe to an increase in Fe(oxy)hydroxide, accompanied by a loss of aromatic and carboxylate function of OM. Summer sampling revealed no significant changes along the gradient, with Fe(oxy)hydroxide and carbohydrates dominating the water phase. Interestingly, settling particles and surface sediments were dominated by Fe(oxy)hydroxides and aliphatic OM. We propose that phototransformation may be an important process that influences the interaction between Fe and OM and, as a consequence, their fate along the spatial gradient. Our study suggests a photochemically induced loss of carboxylate groups, reflected by an increased carbohydrate-to-carboxylate ratio along the gradient, particularly in winter, and generally lower levels during summer. Loss of carboxylate function promotes the formation of Fe(oxy)hydroxides, which in turn, facilitates the aggregation and sinking of OM, particularly aliphatic components. These insights contribute to a broader understanding of carbon cycling and storage in lakes. Future studies should assess the significance of photochemical processes to OM burial and it how may change given trends in Fe and OM in northern regions.

Catalytic and Electrochemical Study of Cu-ZSM-5/MCM-41.

Hierarchically structured micro-mesoporous ZSM-5/MCM-41 composite materials incorporating copper ions were synthesized using pre-synthesized ZSM-5 and cetyltrimethylammonium bromide (CTAB) as a template for forming the MCM-41 structure. The composites were characterized through powder X-ray diffraction, N2 adsorption-desorption, diffuse reflectance spectroscopy (UV-vis DRS), Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, and energy dispersive X-ray spectroscopy. X-ray diffraction confirmed well-ordered ZSM-5 and MCM-41 structures, and UV-vis DRS showed successful copper ion incorporation. N2 adsorption-desorption revealed the presence of both microporous and mesoporous structures. To evaluate their catalytic performance, Cu-incorporated ZSM-5/MCM-41 composite catalysts were assessed through the oxidation reaction of ethylbenzene using tert-butyl hydroperoxide (TBHP) as the oxidizing agent. With a 9% (w/w) Cu-ZM-5 (5 wt % copper-incorporated ZSM-5/MCM-41) catalyst and an oxidant to ethylbenzene molar ratio of 2:1 at 40 °C in the absence of a solvent for 4 h, the process yielded acetophenone (93.2%) as the major product. Additionally, these Cu-incorporated composites were examined as electrode materials for electrochemical storage. Cyclic voltammetry and galvanostatic charge-discharge studies showed that Cu-ZM-5 exhibited pseudocapacitive behavior, with a capacitance of up to 366 F g-1 at a current density of 1 A g-1, surpassing ZSM-5 and ZSM-5/MCM-41. These results highlight Cu-ZM-5's potential as an effective electrode material for electrochemical storage applications like supercapacitors.

Thin Films of Bismuth Oxyhalides (BiOX, X = Cl, Br, I) Deposited by Thermal Evaporation for the Decontamination of Water and Air by Photocatalysis

Thin films of BiOCl, BiOBr, and BiOI (BiOX) were deposited by thermal evaporation for their potential application in the decontamination of water and air through their photocatalytic activity, which was compared among the three. The BiOX thin films were subjected to characterization through X-ray diffraction, high-resolution transmission electron microscopy, and scanning electron microscopy. Additionally, the optical properties were determined from the diffuse reflectance spectrum obtained with a spectrophotometer. To assess the efficacy of the semiconductor films in water decontamination, the evolution of rhodamine B discoloration and its mineralization was monitored by measuring total organic carbon. The decontaminating activity in the air was evaluated in a gas reactor, measuring the conversion of NOx-type gases. The results demonstrated that the thin films of the three oxides exhibited decontaminating photocatalytic activity in both water and air. However, notable distinctions were observed in the photocatalytic activities of the three bismuth oxyhalides in water, while in air, they exhibited similarities. In aqueous environments, the mineralization percentages exhibited notable variation after 96 h, with the BiOBr film displaying a value of 9.2%/mg and the BiOCl film a value of 3.9%/mg. In contrast, the NO conversion rate in the air was approximately 0.6%/mg for the three oxyhalide films.

On the Rubidium Thiotellurate(IV) Rb2[TeS3] and its Tritohydrate Rb2[TeS3] ⋅ 1/3 H2O

AbstractRb2[TeS3] and Rb2[TeS3] ⋅ 1/3 H2O were obtained from rubidium azide (RbN3), tellurium and sulfur in 2 : 1 : 3 molar ratios from evacuated fused silica ampoules at 500 °C under more or less anhydrous conditions. Both compounds crystallize orthorhombically in the space group P212121 (Rb2[TeS3]: a=873.42(6) pm, b=1316.73(9) pm, c=2064.59(14) pm; Rb2[TeS3] ⋅ 1/3 H2O: a=872.97(6) pm, b=1299.82(9) pm, c=2148.26(15) pm, both at –173 °C for Z =12) and contain discrete ψ1‐tetrahedral [TeS3]2− anions (d(Te−S)=232–236 pm) in layerwise arrangements. The difference results from the water of hydration in Rb2[TeS3] ⋅ 1/3 H2O, which increases the coordination numbers of half of the six crystallographically distinct Rb+ cations from six and seven (only sulfur) to seven and almost eight by providing with oxygen from H2O an extra ligand (d(Rb–O)=290–318 pm). Red Rb2[TeS3] transforms pseudo‐topotactically into yellow Rb2[TeS3] ⋅ 1/3 H2O immediately upon contact with moist atmosphere. Both compounds were screened with X‐ray diffraction, Raman and diffuse reflectance spectroscopy as well as thermal analysis.

Preparation of highly active MgO by carbonate hydrogenation and its application in separation of cobalt and nickel

AbstractAs a significant industrial material, MgO is mainly obtained by the pyrolysis of magnesite (magnesium carbonate) under air conditions, producing large amounts of CO2 and contributing to global warming. In this work, the MgO was prepared using the hydrogenation reduction method. The reaction conditions led to CO2 emissions of <1% and an overall temperature decrease of ~80°C. The highly active MgO prepared by hydrogenation reduction led to a precipitation rate of Co and Ni >99% with a short separation time. Electron paramagnetic resonance, CO2 temperature programmed desorption, and diffuse reflectance infrared spectroscopy analyses showed that the MgO prepared by hydrogenation contained oxygen vacancies, which improved the alkalinity of the MgO and promoted the precipitation of Ni2+ and Co2+ by adsorption of hydroxyl oxygen to induce water dissociation, thereby enhancing their separation efficiency.

Structure and optical properties of alkali rare-earth double phosphates of M3RE(PO4)2 (M = K, Rb; RE = Y, La, and Lu)

Designing and synthesizing phosphate nonlinear optical materials with novel structures and excellent properties remains challenging. In this work, the electronic structure and optical properties (second harmonic generation (SHG) response or birefringence) of alkali rare-earth double phosphates M3RE(PO4)2 (M = K, Rb; RE = Y, La, and Lu) are systematically investigated. It is worth mentioning that P31m-Rb3Lu(PO4)2 was successfully synthesized by a flux-method, and the UV–vis–NIR diffuse reflectance spectroscopy showed that Rb3Lu(PO4)2 exhibits a short absorption edge at 207 nm and a high transmittance of 77.9 %. Based on first-principles calculations, the results show that the birefringence of the M3RE(PO4)2 series of crystals exhibits significant differences (0.009-0.028@1064 nm). Subsequently, analysis of the electronic structure and the real-space atom cutting method reveals that rare-earth polyhedra play a major role in enhanced birefringence. Overall, this work enriches the study of nonlinear optical crystals of rare earth phosphates and provides a case for further exploration.