Simple and fast self-polymerization of benzidine using anodic exfloated graphene oxide nanosheet

Nowadays, researchers are looking for green synthesis methods of polymers that solve the disadvantages of polymerization with different initiators and traditional methods. In this work, the self-polymerization process of benzidine by anodic exfloated graphene oxide Nanosheet electrode (AEGO Nsh) is reported for the first time in the world. The self-polymerization of benzidine onto AEGO Nsh electrode was done by an easy and simple method by anodizing the graphite sheet followed by immersing the AEGO Nsh electrode inside the benzidine monomer dissolved in organic and inorganic acid media. The surface morphology of the self-polymerized benzidine (SPB) onto the AEGO Nsh (SPB/AEGO Nsh) electrode was investigated by phone camera and scanning electron microscope (FE-SEM) imaging. The chemical characterization of the SPB/AEGO Nsh electrode was verified through XPS and ATR-IR analysis. Additionally, the self-polymerization of benzidine onto AEGO Nsh electrodes was confirmed by electrochemical tests using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. The results from these investigations unequivocally confirm the self-polymerization of benzidine onto the AEGO Nsh electrode.

Core-shell PdAu nanocluster catalysts to suppress sulfur poisoning

Reducing sulfur poisoning is significant for maintaining the catalytic efficiency and durability of heterogeneous catalysts. We screened PdAu nanoclusters with specific Pd : Au ratios based on Monte Carlo simulations and then carried out density functional calculations to reveal how to reduce sulfur poisoning via alloying. Among various nanoclusters, the core-shell structure Pd13Au42 (Pd@Au) exhibits a low adsorption energy of SO2 (-0.67 eV), comparable with O2 (-0.45 eV) and lower than CO (-1.25 eV), thus avoiding sulfur poisoning during the CO catalytic oxidation. Fundamentally, the weak adsorption of SO2 originates from the negative d-band center of the shell and delocalized charge distribution near the Fermi level, due to the appropriate charge transfer from the core to shell. Core-shell nanoclusters with a different core (Ni, Cu, Ag, Pt) and a Pd@Au slab model were further constructed to validate and extend the results. These findings provide insights into designing core-shell catalysts to suppress sulfur poisoning while optimizing catalytic behaviors.

Functionalization of zirconium-based metal-organic frameworks for gas sensing applications

The functionalization and incorporation of noble metals in metal-organic frameworks have been widely used as efficient methods to enhance their applicability. Herein, a sulfone-functionalized Zr-MOF framework labeled Zr-BPDC-SO₂ (BPDC-SO₂ =dibenzo[b,d]-thiophene-3,7-dicarboxylate 5,5-dioxide) and its Pd-embedded composite were efficiently synthesized by adjusting their functional groups. The obtained compounds were characterized to assess their potential for gas sensing applications. X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, specific surface area measurements, and thermogravimetric analysis were employed to characterize the new sensor materials. The gas sensing properties of the novel functionalized sensor materials were systematically investigated under various temperature, concentration, and gas type conditions. Owing to the strong hydrogen bonds of the sulfonyl groups and Zr₆ clusters in the framework with the hydroxyl groups of ethanol, Zr-BPDC-SO₂ emerged as an effective sensor for ethanol detection. In addition, Pd@Zr-BPDC-SO₂ exhibited efficient hydrogen sensing performance, in terms of sensor dynamics and response. More importantly, the material showed a higher sensing response to hydrogen than to other gases, highlighting the important role of Pd in the Zr-MOF-based hydrogen sensor. The results of the sensing tests carried out in this study highlight the promising potential of the present materials for practical gas monitoring applications.

Photosensitive Tin Sulfur Dioxide Complexes with Unexpected Bonding Modes

Infrared spectra of the matrix-isolated Sn(η² -O₂ S), Sn(η² -OSO), Sn(η² -O₂ S)(η¹ -OSO), Sn(η² -O₂ S)_2, OSn₂ (η² -SO), and Sn(μ₂ -O₂ )SnS molecules were observed following laser-ablated Sn atom reactions with SO₂ during condensation in solid argon. The assignments for the major vibrational modes were confirmed by appropriate S¹⁸ O₂ and ³⁴ SO₂ isotopic shifts and density functional vibrational frequency calculations (B3LYP and BPW91). Interestingly, the mononuclear complexes are interconvertible; that is, irradiation induces the isomerization of Sn(η² -O₂ S) and Sn(η² -O₂ S)(η¹ -OSO) to Sn(η² -OSO) and Sn(η² -O₂ S)₂ , respectively, and vice versa on annealing. However, there is no evidence of isomerization reaction in between the binuclear molecules OSn₂ (η² -SO) and Sn(μ₂ -O₂ )SnS. Bonding in these products is discussed, and the electronic structure changes associated with different bonding types are revealed, which is crucial for the observed photochemical reactions.

Preparation and Properties of SBS-g-GOs-Modified Asphalt Based on a Thiol-ene Click Reaction in a Bituminous Environment

Styrene-butadiene styrene graphene oxide nanoplatelets (SBS-g-GOs)-modified asphalt was prepared by reacting thiolated GOs (GOs-SH) with SBS in asphalt using a thiol-ene click reaction. The temperature resistance and mechanical properties of asphalts were analyzed by dynamic shear rheology (DSR) and multiple-stress creep-recovery (MSCR) tests, which revealed that an optimum amount of GOs-SH (0.02%) can effectively improve the low temperature and anti-rutting performance of SBS asphalt. Segregation experiments showed that SBS-g-GOs possessed good stability and dispersion in base asphalt. Fluorescence microscopy results revealed that the addition of GOs-SH promoted the formation of SBS network structure. Textural and morphological characterization of GOs-SH and SBS were achieved by Fourier transform infra-red (FT-IR) spectroscopy, energy-dispersive X-ray spectroscopy (EDX), atomic-force microscopy (AFM), X-ray diffraction (XRD), and scanning electron microscopy (SEM), while surface chemical composition was tested by X-ray photoelectron spectroscopy (XPS). Based on textural characterization data, a suitable reaction mechanism was proposed that involved the preferential reaction between GOs-SH and 1,2 C=C of SBS. The currently designed GOs-SH incorporated asphalt via thiol-ene click reaction provides new ideas for the preparation of modified asphalt with enhanced mechanical properties for target-oriented applications.

On the prediction of core level binding energies in molecules, surfaces and solids

Core level binding energies, directly measured by X-ray photoelectron spectroscopy (XPS), provide unique information regarding the chemical environment of atoms in a given system. However, interpretation of XPS in extended systems may not be straightforward and requires assistance from theory. The different state-of-the-art theoretical methods commonly used to approach core level binding energies and their shifts with respect to a given reference are reviewed and critically assessed with special emphasis on recently developed theoretical methods and with a focus on future applications in materials and surface sciences.

Applying a Nonspin-Flip Reaction Scheme to Explain for the Doublet Sulfide Oxides SMO2 Observed for the Reactions of SO2 with V(4F), Nb(6D), and Ta(4F)

Energy profiles linking the reactants M + SO2 (M = V(4F), Nb(6D;4F), and Ta(4F)) with the products observed for these reactions under matrix-isolation conditions, mainly the oxide complex OV(η2-SO) and the sulfide oxides SVO2, SNbO2, and STaO2, have been obtained from DFT and CASSCF-MRMP2 calculations. For each of these interactions, the radical fragments MO + SO can be reached from the lowest-lying quadruplet electronic states of the reactants. As the quadruplet and doublet radical asymptotes that vary only in the spin of the unpaired parallel electrons of the nonmetallic fragment are degenerated, a second reaction leading to the rebounding of the radical fragments can take place through both multiplicity channels. Reaction along the doublet pathway leads in each case to the most stable structure for the oxide SMO2. For the vanadium interaction, recombination of the radical species through the quadruplet channel explains for the oxide product OV(η2-SO).

Ultrafast x-ray photoelectron spectroscopy in the microsecond time domain

We introduce a new approach for ultrafast in situ high-resolution X-ray photoelectron spectroscopy (XPS) to study surface processes and reaction kinetics on the microsecond timescale. The main idea is to follow the intensity at a fixed binding energy using a commercial 7 channeltron electron analyzer with a modified signal processing setup. This concept allows for flexible switching between measuring conventional XP spectra and ultrafast XPS. The experimental modifications are described in detail. As an example, we present measurements for the adsorption and desorption of CO on Pt(111), performed at the synchrotron radiation facility BESSY II, with a time resolution of 500 μs. Due to the ultrafast measurements, we are able to follow adsorption and desorption in situ at pressures of 2 × 10(-6) mbar and temperatures up to 500 K. The data are consistently analyzed using a simple model in line with data obtained with conventional fast XPS at temperatures below 460 K. Technically, our new approach allows measurement on even shorter timescales, down to 20 μs.

Dehydrogenation of dodecahydro-N-ethylcarbazole on Pt(111)

Sloshing hydrogen: Liquid organic hydrogen carriers are high-boiling organic molecules, which can be reversibly hydrogenated and dehydrogenated in catalytic processes and are, therefore, a promising chemical hydrogen storage material. One of the promising candidates is the pair N-ethylcarbazole/perhydro-N-ethylcarbazole (NEC/H₁₂-NEC). The dehydrogenation and possible side reactions on a Pt(111) surface are evaluated in unprecedented detail.