RSC Advances最新文献

Here, we performed first-principles density functional theory (DFT) modeling coupled with the Boltzmann transport equation to explore hydrothermally synthesized bismuth oxyhalides (BiOX, X = Cl, Br, I) nanoparticles. The correlation between BiOX crystallographic and elastic properties was established from the equation of state and elastic tensor simulations. The phonon calculations inferred the dynamical stability and infrared activity of BiOX. The Raman absorptions were reproduced in Raman tensor simulations. The field emission scanning electron microscopy revealed average particle sizes of 154, 221, and 71 nm for BiOCl, BiOBr, and BiOI, respectively. The elemental identification and chemical state analysis were performed with energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. The diffuse reflectance-derived indirect electronic band gaps of BiOCl (3.54 eV), BiOBr (2.83 eV), and BiOI (1.85 eV) were modeled from the hybrid Heyd–Scuseria–Ernzerhof screened and tuned approach with long-range van der Waals interaction and relativistic spin–orbit coupling. The effective mass analysis revealed that holes in BiOCl and BiOBr are heavier than electrons, whereas the opposite holds in BiOI. High degree of anisotropy was revealed in lattice thermal transport in BiOX. The thermoelectric figure of merit ZT turned out to be 0.51, 0.76, and 1.49 near 990 K in BiOCl, BiOBr, and BiOI, respectively, indicating them as promising thermoelectric materials. The photoluminescence emissions of BiOCl, BiOBr, and BiOI were detected in the opto-electronically favorable visible ranges of 366–521, 335–658, and 393–658 nm, respectively. The theoretical electronic band alignment analysis of BiOX facilitated the straddling of the relevant redox potentials, supporting the photocatalytic degradation of rhodamine B dye. In essence, this work provides comprehensive information on functional properties of BiOX nanoparticles relevant in thermoelectric, optoelectronic, and photocatalytic applications with a combined DFT-experimental approach.

A class of chemical warfare agents and their facile use in terrorist attacks underscores the need to develop accurate system to detect these chemicals. For this paper, we synthesized and developed a new highly selective and sensitive fluorescence probe based on fluoresceinyloxime for the detection of a nerve agent mimic. The synthesized probe underwent an abnormal cascade reaction from oxime to isoxazole in DMF/HEPES buffer (1/1, v/v, pH 7.0). The probe responded by quenching the fluorescence intensity in very short time (within seconds) and gave a naked eye detection by changing the colour of the solution from dark orange to very light green with a detection limit of 0.18 µM. The probe not only shows sensitivity and selectivity in the liquid phase, but can also be applied for the detection of nerve agents in the vapour phase with a clear colour change easily observed by the naked eye.

CO₂ switchable surfactants show broad application prospects in the treatment of oil-based drilling cuttings due to their reversible ‘active–inactive’ state switching characteristics. This study focuses on the typical guanidinium-based CO₂-responsive surfactant dodecyl tetramethyl guanidine (DTMG) and its protonated form (DTMGH), using a full-atom molecular dynamics simulation system to investigate their interfacial behavior and emulsification/demulsification mechanisms. DTMGH was easier to reach saturation at the interface due to the head-based positive charge repulsion. In terms of emulsification, DTMGH distributed more evenly, effectively encapsulating oil droplets to form stable oil-in-water emulsions. In contrast, DTMG cannot effectively maintain the dispersion of oil droplets, ultimately leading to demulsification. DTMGH exhibited stronger interfacial tension-reducing capabilities than DTMG. The DTMGH system formed a thicker interfacial adsorption layer due to the electrostatic repulsion of protonated head groups and hydrophilicity. Protonation transformed N1 from a hydrogen bond acceptor to a donor, weakening N2's hydration capacity, ultimately altering interfacial hydrophilicity and molecular arrangement. Additionally, the intensity of electrostatic repulsion was a key factor regulating surfactant molecule behavior during emulsification and demulsification. Solvent-accessible surface area revealed that the DTMGH system maintains higher surfactant and oil phase dispersion, directly related to emulsion formation. Our study elucidated the mechanism of action of guanidino-based CO₂-responsive surfactants at the molecular level, providing a theoretical foundation for the development of more efficient CO₂-responsive surfactant systems.

An efficient heterogeneous Electro-Fenton (EF) process was developed using a catalyst based on hydroxyapatite derived from bovine bone bio-waste (HAp_Bio), doped with iron through ion exchange (Fe_(x)-HAp_Bio), for the degradation and mineralization of the antibiotic Cefuroxime Sodium (CFX-Na) in an aqueous medium. The materials were synthesized and characterized by different techniques including X-ray diffraction (XRD), Fourier transform infrared absorption spectroscopy (FTIR), scanning electron microscopy coupled with EDX (SEM-EDX) and X-ray fluorescence spectroscopy (XRF). These analyses demonstrated the high structural stability of HAp_Bio despite iron doping, a homogeneous dispersion of iron, the presence of functional groups characteristic of hydroxyapatite such as hydroxyl ions OH⁻, H₂O, PO₄³⁻, and CO₃²⁻, as well as a total iron content of 5.687 wt%. The catalytic activity of the catalyst was evaluated without any prior adjustment to the pH of the solutions. The results showed that an optimal doped iron content of 0.5%, with a catalyst concentration of 1 g L⁻¹ applying a current of 400 mA, allowed total degradation to be achieved in 25 min and almost complete mineralization after 5 hours of electrolysis. Radical scavenging experiments using DMSO and chloroform confirmed that hydroxyl radicals (˙OH) were the primary oxidizing species, while hydroperoxyl (˙O₂H) and superoxide (O₂˙⁻) radicals were also present in the degradation process. To describe the formation pathways of these reactive species a reaction mechanism was proposed. Also, the catalyst demonstrated good stability after several reuse cycles. Moreover, heterogeneous EF treatment enhanced the biodegradability of the solution after 90 minutes, and therefore, allowed its subsequent low-cost biological treatment. After 17 days, aerobic biological post-treatment achieved almost complete mineralization, which indicated the overall efficiency, sustainability, and less energy consumption of the process.

Using the M06-2X-D3/def2-TZVP level of theory, we investigated the 1,3-addition reactions of methyl iodide (CH₃I) with a series of heavy imine analogues, G13=As-Rea (where G13 = group 13 element), which feature a mixed G13–As–Ge backbone. Theoretical evidence reveals that the bonding character of the G13As moiety varies depending on the identity of the G13 center, exhibiting either donor–acceptor (singlet–singlet) or electron-sharing (triplet–triplet) interactions. According to our computational results, all G13=As-Rea compounds—except for the BAs analogue—readily undergo 1,3-addition with CH₃I. Energy decomposition analysis combined with natural orbitals for chemical valence (EDA-NOCV), as well as frontier molecular orbital (FMO) theory, indicates that the dominant interaction in these 1,3-addition reactions is the donation from the lone pair on the Ge atom (G13=As-Rea) into the σ* orbital of the C–I bond in CH₃I. This contrasts with a less favorable interaction involving the filled σ(C–I) orbital donating into the vacant p–π* orbital on G13. The calculated activation barriers are largely governed by the deformation energy of the G13=As-Rea species, which, in turn, is significantly influenced by the relativistic effects associated with the heavy G13 central atom. Our computational findings reveal a clear correlation between the mass of the G13 atom and the reactivity of the corresponding G13=As-Rea species in 1,3-addition reactions. As the atomic weight of G13 increases, the relativistic effects become more pronounced, resulting in a contracted ∠G13–As–Ge angle. This geometric feature facilitates superior orbital overlap with CH₃I, thereby lowering the activation barrier and promoting reactivity.

Despite recent significant advancements in antibacterial applications of copper-based metal–organic frameworks (Cu MOFs), the synthesis of a high-copper-content MOF remains elusive. Here we proposed a multi-coordination strategy through a direct solvothermal reaction of Cu ions and formic acid, which yielded a three-dimensional MOF (denoted as Cu-FA) containing 32% Cu. Through single crystal X-ray diffraction analyses, the precise spatial structure of Cu-FA was determined. Two types of Cu⋯O coordination bonds with varying bond energies were found in Cu-FA, enabling a multistage Cu release protocol to balance the antibacterial efficacy and biocompatibility. As a result, Cu-FA presented significant antibacterial activity against Escherichia coli, with an inactivation rate of 99.76%. Overall, this study not only establishes a viable strategy for synthesizing high-copper-content MOFs, deepening the understanding of their multilayer structures, but also providing a new insight into the exploration of antibacterial applications.

Two-dimensional MXenes have recently emerged as potential candidates for their excellent electrical and mechanical properties. We report the controlled modulation of thermoelectric properties in Ti₃C₂T_x flexible membranes via vacuum annealing. The as-prepared flexible membrane shows the highest electrical conductivity (∼5000 S m⁻¹ at 373 K) and slightly estimated ZT value of 4.4 × 10⁻³ at 420 K due to preserved surface terminations and intercalated water contents. Notably, annealing at 300 °C enhances the Seebeck coefficient (∼450 µV K⁻¹) and optimizes the power factor (∼105 µW m⁻¹ K⁻² at 450 K), whereas high temperature annealing (400 °C) significantly reduced thermoelectric performance due to excessive oxidation and degradation of the membrane. This work highlights that the tunability of MXene films through controlled annealing and surface functional group modification can significantly enhance the performance of thermoelectric materials for room- to mid-temperature range applications. The investigation of MXenes' thermoelectric properties opens new avenues for their use in flexible electronics and wearable devices.

Here, we demonstrate NiCo₂O₄ nanoparticle-catalyzed dehydrogenative esterification and amidation of primary alcohols to esters of fatty acids and amides under microwave irradiation, without the need for any oxidant, achieving excellent yields of esters (50–92%) and amides (72–80%). The NiCo₂O₄ nanomaterial was prepared through co-precipitation, and its composition, morphology, structure, and textural properties were analyzed via powder XRD, FESEM, EDX, TEM, and BET. The crystallite size was found to be 121.69 nm using the Scherrer equation, by considering the FWHM of the (311) diffraction plane. The FESEM and EDS analysis revealed the formation of spherical-shaped granules with a mean size of 0.251 µm and their elemental composition. Furthermore, HRTEM images with a mean size of 2.25 nm confirmed the formation of spherical NiCo₂O₄ nanoparticles. The mesoporous nature of the material is analyzed by the BET surface area (33.81 m² g⁻¹) and average pore diameter 23.49 nm. The NiCo₂O₄ nanoparticles remained stable throughout the reaction process and were reusable for up to eight cycles. The catalytic nature of NiCo₂O₄ has been proved by cyclic voltametric studies of fresh and recycled catalysts. The present dehydrogenative esterification and amidation protocol offers several advantages, for example, robust and recyclable NiCo₂O₄ nanoparticles as a catalyst, oxidant- and solvent-free reaction conditions, microwave-assisted faster reaction rate, excellent isolated yields of products, etc.

Accurate detection of albumin proteins is crucial for diagnosing different diseases. A fluorescent sensor has been developed using cerium (Ce) doped carbon quantum dots (CQDs) to detect bovine serum albumin (BSA) in blood and urine samples. Pristine CQDs and Ce-CQDs were synthesized through citric acid pyrolysis. CQDs and Ce-CQDs exhibited emission peaks at 415 nm and 426 nm, respectively. Based on the photoluminescence (PL) enhancement of Ce-CQDs resulting from adding BSA, BSA was quantified within two minutes. This biosensor was selective and sensitive towards BSA in the concentrations ranging from 1 to 1000 µM with a high correlation coefficient and a low detection limit of 0.98 µM (6.5 × 10⁻² g L⁻¹), which meets the requirement well for clinical analysis. The practical usefulness of Ce-CQDs as a fluorescent biosensor was confirmed by accurately quantifying BSA in human serum and urine samples with satisfactory recovery percentages.

This study explores the influence of various precursors including ammonium metatungstate (AMT) and peroxotungstic acid (PTA) in water, and tungsten hexachloride (WCl₆ in MeOH or EtOH), as well as the role of ammonium chloride incorporation on the structural, morphological, and photoelectrochemical characteristics of WO₃ layers synthesized by spray pyrolysis. X-ray diffraction (XRD) analysis revealed that films annealed at 550 °C crystallized in the monoclinic phase of WO₃ with a polycrystalline structure without amorphous parts. Different morphological features of the samples were identified by scanning electron microscopy (SEM): dense grains for films formed using PTA, aggregated grains for films synthesized from AMT, smooth and uniform surfaces for films based on WCl₆, and porous architectures resulting from NH₄Cl incorporation. Photoelectrochemical measurements under UV and simulated solar illumination demonstrated that AMT/NH₄Cl – derived WO₃ films significantly enhanced the initial photocurrent density, reaching values of up to ∼3 mA cm⁻² under UV light. Topological energy dispersive spectroscopy (EDS) revealed the existence of Cl rich areas responsible for this effect. With prolonged exposition to light and bias, Cl in these areas was oxidatively exhausted and average current densities as in samples obtained with other precursors were obtained. These findings highlight the critical role of precursor selection and doping in determining the photoelectrochemical performance of spray-deposited WO₃ photoanodes.