Olssonjordan1426

We identify the "missing" 1D-phosphorus allotrope, red phosphorus chains, formed in the interior of tip-opened single-walled carbon nanotubes (SWCNTs). Via a comprehensive experimental and theoretical study we show that in intermediate diameter cavities (1.6-2.9 nm), phosphorus vapor condenses into linear P8]P2 chains and fibrous red-phosphorus type cross-linked double-chains. Thermogravimetric and X-ray photoelectron spectroscopy analysis estimates ∼7 atom % of elemental phosphorus in the sample, while high-resolution energy dispersive X-ray spectroscopy mapping reveals that phosphorus fills the SWCNTs. High-resolution transmission electron microscopy (HRTEM) shows long chains inside the nanotubes with varying arrangement and packing density. A detailed match is obtained between density functional theory (DFT) simulations, HRTEM, and low-frequency Raman spectroscopy. Notably, a signature spectroscopic signal for phosphorus chain cross-linking is identified. When coupled with reinterpretation of literature data and wide-ranging DFT calculations, these results reveal a comprehensive picture of the diameter dependence of confined 1D-phosphorus allotropes.We explore the effect of solvation and micropore structure on the energy storage performance of electrical double layer capacitors using constant potential molecular dynamics simulations of realistically modeled nanoporous carbon electrodes and ionic liquid/organic solvent mixtures. We show that the time-dependent charging profiles of electrodes with larger pores reach the plateau regime faster, while the charging time has a nonmonotonic dependence on ion concentration, mirroring the composition dependence of bulk electrolyte conductivity. When the average pore size of the electrode is similar to or slightly larger than the size of a solvated ion, the solvation enhances ion electrosorption into nanopores by disrupting anion-cation coordination and decreasing the barrier to counterion penetration while blocking the co-ions. In these systems, areal capacitance exhibits a significant nonmonotonic dependence on ion concentration, in which capacitance increases with the introduction of solvent in the concentrated regime followed by a decrease with further dilution. This gives rise to a maximum in capacitance at intermediate dilution levels. When pores are significantly larger than solvated ions, capacitance maximum weakens and eventually disappears. These findings provide novel insights on the combined effect of electrolyte composition and electrode pore size on the charging kinetics and equilibrium behavior of realistically modeled electrical double layer capacitors. Generalization of the approach developed here can facilitate the rational optimization of material properties for electrical double layer capacitor applications.Criegee intermediates, derived from ozonolysis of alkenes and recognized as key species in the production of nonphotolytic free radicals, play a crucial role in atmospheric chemistry. Here, we present a spectrometer based on synchronized two-color time-resolved dual-comb spectroscopy, enabling simultaneous spectral acquisitions in two molecular fingerprint regions near 2.9 and 7.8 μm. Upon flash photolysis of CH2I2/O2/N2 gas mixtures, multiple reaction species, involving the simplest Criegee intermediates (CH2OO), formaldehyde (CH2O), hydroxyl (OH) and hydroperoxy (HO2) radicals are simultaneously detected with microsecond time resolution. The concentration of each molecule can be determined based on high-resolution rovibrational absorption spectroscopy. With quantitative detection and simulation of temporal concentration profiles of the targeted molecules at various conditions, the underlying reaction mechanisms and pathways related to the formation of the HOx radicals, which can be generated from decomposition of initially energized and vibrationally excited Criegee intermediates, are explored. This approach capable of achieving multispectral measurements with simultaneously high spectral and temporal resolutions opens up the opportunities for quantification of transient intermediates and products, thus, enabling elucidation of complex reaction mechanisms.As one of the important diffractive optical elements, the submicron gratings on flexible substrates can actively and precisely control the dispersion and steering characteristics of beams and have been widely applied in deformation detection technologies. Herein, we propose a spatially modulated femtosecond laser-assisted molding technology for efficiently fabricating high-uniformity large-area submicron gratings with tunable periods on flexible substrates. The technology first uses a cylindrically focused femtosecond laser-assisted chemical etching method to form a regular submicron grating on silicon; subsequently, the structure is cast with polydimethylsiloxane, a useful flexible substrate with a small Young's modulus, and cured to obtain a high-uniformity large-area submicron grating with a tunable period. The grating exhibits high mechanical stability and sensitivity and favorable optical properties. In the present study, as the deformation of the grating increased from 0 to 10%, the diffraction angle changed by 6.5°. Under illumination by a broad-band white-light source, distinguishable multicolor diffraction patterns were clearly observed. Drawing on this characteristic, we fabricated a deformation sensor. The grating fabricated by using the proposed technology also has potential applications in optical sensors and soft robots.We report the peptide-programmed fractal assembly of silver nanoparticles (AgNPs) in a diffusion-limited aggregation (DLA) mode, and this change in morphology generates a significant color change. We show that peptides with specific repetitions of defined amino acids (i.e., arginine, histidine, or phenylalanine) can induce assembly and coalescence of the AgNPs (20 nm) into a hyperbranched structure (AgFSs) (∼2 μm). The dynamic process of this assembly was systematically investigated, and the extinction of the nanostructures can be modulated from 400 to 600 nm by varying the peptide sequences and molar ratio. According to this rationale, two strategies of SARS-CoV-2 detection were investigated. The activity of the main protease (Mpro) involved in SARS-CoV-2 was validated with a peptide substrate that can bridge the AgNPs after the proteolytic cleavage. A sub-nanomolar limit of detection (0.5 nM) and the capacity to distinguish by the naked eye in a wide concentration range (1.25-30 nM) were achieved. Next, a multichannel sensor-array based on multiplex peptides that can visually distinguish SARS-CoV-2 proteases from influenza proteases in doped human samples was investigated.Electrochemical reduction of CO2 into valuable fuels and chemicals is a promising route of replacing fossil fuels by reducing CO2 emissions and minimizing its adverse effects on the climate. Tremendous efforts have been carried out for designing efficient catalyst materials to selectively produce the desired product in high yield from CO2 by the electrochemical process. Selleckchem Tomivosertib In this work, a strategy is reported to enhance the electrochemical CO2 reduction reaction (ECO2RR) by constructing an interface between a metal-based alloy (PdIn) nanoparticle and an oxide (In2O3), which was synthesized by a facile solution method. The oxide-derived PdIn surface has shown excellent eCO2RR activity and enhanced CO selectivity with a Faradaic efficiency (FE) of 92.13% at -0.9 V (vs RHE). On the other hand, surface PdO formation due to charge transfer on the bare PdIn alloy reduces the CO2RR activity. With the support of in situ (EXAFS and IR) and ex situ (XPS, Raman) spectroscopic techniques, the optimum presence of the Pd-In-O interface has been identified as a crucial parameter for enhancing eCO2RR toward CO in a reducing atmosphere. The influence of eCO2RR duration is reported to affect the overall performance by switching the product selectivity from H2 (from water reduction) to CO (from eCO2RR) on the oxide-derived alloy surface. This work also succeeded in the multifold enhancement of the current density by employing the gas diffusion electrode (GDE) and optimizing its process parameters in a flow cell configuration.The development of inexpensive and abundant catalysts with high activity, selectivity, and stability for the oxygen reduction reaction (ORR) is imperative for the widespread implementation of fuel cell devices. Herein, we present a combined theoretical-experimental approach to discover and design first-row transition metal antimonates as excellent electrocatalytic materials for the ORR. Theoretically, we identify first-row transition metal antimonates─MSb2O6, where M = Mn, Fe, Co, and Ni─as nonprecious metal catalysts with good oxygen binding energetics, conductivity, thermodynamic phase stability, and aqueous stability. Among the considered antimonates, MnSb2O6 shows the highest theoretical ORR activity based on the 4e- ORR kinetic volcano. Experimentally, nanoparticulate transition metal antimonate catalysts are found to have a minimum of a 2.5-fold enhancement in intrinsic mass activity (on transition metal mass basis) relative to the corresponding transition metal oxide at 0.7 V vs RHE in 0.1 M KOH. MnSb2O6 is the most active catalyst under these conditions, with a 3.5-fold enhancement on a per Mn mass activity basis and 25-fold enhancement on a surface area basis over its antimony-free counterpart. Electrocatalytic and material stability are demonstrated over a 5 h chronopotentiometry experiment in the stability window identified by theoretical Pourbaix analysis. This study further highlights the stable and electrically conductive antimonate structure as a framework to tune the activity and selectivity of nonprecious metal oxide active sites for ORR catalysis.Electrocatalytic oxidation of simple organic molecules offers a promising strategy to combat the sluggish kinetics of the water oxidation reaction (WOR). The low potential requirement, inhibition of the crossover of gases, and formation of value-added products at the anode are benefits of the electrocatalytic oxidation of organic molecules. Herein, we developed cobalt-nickel-based layered double hydroxide (LDH) as a robust material for the electrocatalytic oxidation of alcohols and urea at the anode, replacing the WOR. A facile synthesis protocol to form LDHs with different ratios of Co and Ni is adapted. It demonstrates that the reactants could be efficiently oxidized to concomitant chemical products at the anode. The half-cell study shows an onset potential of 1.30 V for benzyl alcohol oxidation reaction (BAOR), 1.36 V for glycerol oxidation reaction (GOR), 1.33 V for ethanol oxidation reaction (EOR), and 1.32 V for urea oxidation reaction (UOR) compared with 1.53 V for WOR. Notably, the hybrid electrolyzer in a full-cell configuration significantly reduces the overall cell voltage at a 20 mA cm-2 current density by ∼15% while coupling with the BAOR, EOR, and GOR and ∼12% with the UOR as the anodic half-cell reaction. Furthermore, the efficiency of hydrogen generation remains unhampered with the types of oxidation reactions (alcohols and urea) occurring at the anode. This work demonstrates the prospects of lowering the overall cell voltage in the case of a water electrolyzer by integrating the hydrogen evolution reaction with suitable organic molecule oxidation.