Three-Dimensional Networked Ni-Phyllosilicate Catalyst for CO₂ Methanation: Achieving High Dispersion and Enhanced Stability at High Ni Loadings

It is a great challenge for nickel-based catalysts to obtain high-temperature stable Ni nanoparticles with high dispersion at high loadings. To address this problem, a group of three-dimensional (3D) networked nickel phyllosilicate catalysts were prepared through the hydrothermal reaction of 3D-SBA-15 and soluble nickel salts (Ni­(NO3)2 or Ni­(CH3COO)2) and were used for the CO2 methanation reaction to produce CH4 (substitute natural gas). The flower-like nanosheets corresponding to Ni3Si2O5(OH)4 are uniformly generated on the surface of 3D-SBA-15 and become much denser with increasing hydrothermal time, with Ni contents varying in the range of 24.22–30.72 wt %. Upon 750 °C reduction of phyllosilicate materials, small-sized Ni particles (<5 nm) can highly disperse and be confined into the silica and unreduced phyllosilicate support due to the strong interaction of the nickel and complex support. In addition, a Ni/3D-SBA-15 catalyst with the high Ni content of 30 wt % was also synthesized for comparison by an incipient wetness impregnation method. For the CO2 methanation reaction, the fabricated phyllosilicate catalyst achieved a higher maximum CH4 yield of 80.4% at 400 °C and exhibited a higher long-term stability of 100 h as compared to the impregnated sample. It was noted that the phyllosilicate catalyst also exhibited high hydrothermal stability at 600 °C under 100% steam. The enhanced catalytic performance was attributed to the excellent property of nickel phyllosilicate and the special pore structure derived from 3D-SBA-15, which could significantly improve the Ni dispersion and increase CO2 adsorption and H2 uptake as well as the interaction of nickel–support

Insights into solvent polarity associated geometries and ESIPT behaviours for Prz3HC: a theoretical study

Given the potential significance of 3-hydroxychromone derivatives, our focus in this study is to investigate the solvent-polarity-associated photo-induced behaviours for 3-hydroxy-2-(1-ethyl-1H-pyrazol-3-yl)-4H-chromen-4-one (Prz3HC). We firstly examine the coexistence of three conformations (i.e. Prz3HC-I, Prz3HC-II and Prz3HC-III) and present a mechanism for their coexistence between Prz3HC-I and Prz3HC-III. Notably, non-polar solvents contain mainly Prz3HC-I while polar solvents contain mainly Prz3HC-III. Analysing infrared vibrational spectra and geometrical variations between S0 and S1 states, we demonstrate a hydrogen bonding strengthening phenomenon that facilitates excited-state intramolecular proton transfer (ESIPT) behaviour for both Prz3HC-I and Prz3HC-III. To qualitatively investigate photo-induced behaviours, by frontier molecular orbitals (MOs), we have discovered that charge redistribution significantly enhances the propensity for ESIPT. By comparing the barriers of potential energy curves (PECs) for twisting dihedral angles and ESIPT paths, we have unequivocally ruled out any mutual transformations in the S1 state. We also propose a solvent-polarity-regulated ESIPT behaviour for Prz3HC-I and Prz3HC-III. Furthermore, through an exploration of transition states (TS), we have further scrutinised the intricate mechanism underlying ESIPT. We sincerely hope this study can elucidate the solvent-polarity-regulated excited-state behaviours of Prz3HC while simultaneously paving the way for future explorations and applications of other 3-hydroxychromone derivatives.</p

Understanding the Role of Intra- and Intermolecular Interactions in the Formation of Single- and Double-Helical Structures of Aromatic Oligoamides: A Computational Study

The generalized energy-based fragmentation (GEBF) approach has been implemented to extend the applications of density function theory (DFT) with empirical van der Waals (vdW) correction (Wu, Q.; Yang, W. T. J. Chem. Phys. 2002, 116, 515.) to large supramolecular systems with extensive π−π stacking interactions. This mixed approach, DFT(vdW)-GEBF, is applied to investigate the energies and structures of several aromatic oligoamide foldamers. Our calculations show that the formation of single helical structures is mainly driven by the stacking interaction between neighboring aromatic rings, further stabilized by the intramolecular hydrogen bonds of the backbone. The dimerization of two single helical strands to form the double helical structure is an energetically favorable process, which is mainly driven by extensive interstrand aromatic−aromatic interactions. However, the dimerization energy tends to decrease significantly for longer oligomeric strands

Estimation on the Individual Hydrogen-Bond Strength in Molecules with Multiple Hydrogen Bonds

A simple atom-replacement approach is proposed for estimating the individual contributions of each intermolecular hydrogen bond (HB) in multiple hydrogen-bonded systems. The approach is validated by calculations on the homodimer of formylformamide and then applied to nucleic acid base pairs (adenine−thymine and guanine−cytosine) and some quadruply hydrogen-bonded dimers. With the help of this method, it is easy to distinguish the relative strength of each HB, and identify the main factors contributing to the total binding energies of multiple HBs

Table1_Understanding Ecological Agricultural Technology Adoption in China Using an Integrated Technology Acceptance Model—Theory of Planned Behavior Model.pdf

With the development of the economy and society, environmental pollution and resource waste problems are emerging, especially in agricultural production, and the adoption of ecological agricultural technologies is a prerequisite to alleviate ecological pressure. Based on the Technology Acceptance Model—Theory of Planned Behavior (TAM-TPB) and using research data from Hubei, Hunan, and Anhui provinces, this paper empirically analyzes the factors influencing farmers’ intention to adopt rice and shrimp crop technologies using the PLS-SEM method. The configuration path of high technology intention was further investigated by the fsQCA method. The results showed that: 1) farmers’ intention to adopt rice-shrimp crop technology was mainly positively influenced by behavioral attitude, subjective norm, perceived behavioral control, behavioral attitude; 2) Perceived usefulness and perceived ease of use had a direct effect on farmers’ intention to adopt and an indirect effect with behavioral attitude as a mediating variable, while perceived ease of use had a positive effect and perceived usefulness did not. In doing so, four configuration paths of high technology acceptance intention were obtained. Given this, this paper makes relevant suggestions, suggesting that the relevant departments focus on the comprehensive benefits of rice-shrimp crop technology; agricultural technology departments provide technical assistance to farmers, and village committees organize regular inter-farmer exchanges.</p

DFT/TDDFT based study to decipher the excited state intramolecular proton transfer process for 3-benzothiazol-2-yl-2-hydroxy-5-methyl-benzaldehyde-oxime

In this study, we theoretically investigate the interactions of hydrogen bonding in excited states and the mechanism of intramolecular proton transfer (ESIPT) for the novel compound 3-benzothiazol-2-yl-2-hydroxy-5-methyl-benzaldehyde-oxime (HBT-phos) theoretically. Herein, the effects of atomic electronegativity of chalcogen (O, S and Se) are also focused. Firstly, employing quantum theory of atoms-in-molecules (QTAIM) method, we confirm intrinsic quality of O-H···N within HBT-phos derivatives (HBT-phos-O, HBT-phos-S and HBT-phos-Se). By astutely examining changes in geometries and infrared (IR) spectra, we elegantly demonstrate O-H···N is remarkably strengthened in S1 state, indicating a pronounced tendency towards ESIPT. Computational hydrogen bonding energies further magnificently support this conclusion. Probing into photo-induced excitation, we discover heightened electronic densities surrounding N atom that play pivotal roles in attracting protons, thereby facilitating ESIPT. Ultimately, upon comparing potential energy curves in excited states, we deduce ESIPT process is expected to be exceptionally rapid with low atomic electronegativity (O → S → Se), which elucidates why detecting fluorescence peak of HBT-phos-S itself proves challenging in experiment. This study not only fills the void in understanding ESIPT mechanism within HBT-phos derivatives and authentically reveals its unambiguous mechanism, but also presents atomic-electronegativity-dependent ESIPT behaviour and the explanation for fluorescence quenching observed in prior experiment.</p

Experimental and Computational Evidence for the Reduction Mechanisms of Aromatic <i>N</i>‑oxides by Aqueous Fe^II–Tiron Complex

A combined experimental-theoretical approach was taken to elucidate the reduction mechanisms of five representative aromatic <i>N</i>-oxides (ANOs) by Fe^II–tiron complex and to identify the rate-limiting step. Based on the possible types of complexes formed with the reductant, three groups of ANOs were studied: type I refers to those forming 5-membered ring complexes through the N and O atoms on the side chain; type II refers to those forming 6-membered ring complexes through the <i>N</i>-oxide O atom and the O atom on the side chain; and type III refers to complexation through the <i>N</i>-oxide O atom only. Density functional theory calculations suggested that the elementary reactions, including protonation, N–O bond cleavage, and the second electron transfer processes, are barrierless, indicating that the first electron transfer is rate-limiting. Consistent with the theoretical results, the experimental solvent isotope effect, KIE_H, for the reduction of quinoline <i>N</i>-oxide (a type III ANO) was obtained to be 1.072 ± 0.025, suggesting protonation was not involved in the rate-limiting step. The measured nitrogen kinetic isotope effect, KIE_N, for the reduction of pyridine <i>N</i>-oxide (a type III ANO) (1.022 ± 0.006) is in good agreement with the calculated KIE_N for its first electron transfer (1.011–1.028), confirming that the first electron transfer is rate-limiting. Electrochemical cell experiments demonstrated that the electron transfer process can be facilitated significantly by type I complexation with FeL₂^6– (1:2 Fe^II–tiron complex), to some extent by type II complexation with free Fe^II, but not by weak type III complexation

Tailoring Structural, Electronic, Optical, and Photocatalytic Properties of Y₂Ti₂O₇ through a Passivated Codoping Approach

The large band gap of the Y2Ti2O7 photocatalyst has limited its application only in the ultraviolet region. To enhance its photocatalytic activity for overall water splitting in the visible-light region, we have utilized a passivated codoping approach to construct eleven (X + M)-doped Y2Ti2O7 systems (X = C, N, M = Ti, V, Zr, Nb, Mo, Hf, Ta, W), where a Ti/Y site is replaced with a metal dopant. The calculated negative formation energies indicate that all of the (X + M)-doped systems are easy to synthesize, especially under the O-rich condition. The implantation of dopants can change the crystal structure to different extents. The less the deformation of the crystal, the easier the formation of the (X + M)-doped Y2Ti2O7. The passivated codoping can effectively narrow the band gap without generating isolated defect states in the forbidden gap. (X + M)-doped Y2Ti2O7 retains the direct band gap characteristics and possesses the separation rate of photogenerated carriers similar to or even higher than that of the pure crystal. Compared to (N + M)-doped systems, (C + M)-doped systems exhibit more remarkable influence on narrowing the band gap and extending the absorption edge mainly because the C dopant has deeper acceptor energy levels and a stronger interaction with the metal dopant than the N dopant. The capabilities of photooxidation and photoreduction of water have been enhanced by adopting the codoping strategy. By considering the binding energy, band gap, optical absorption, and the relative position of band edges, we propose that (C + Mo)-, (C + W)-, (N + V)-, (C + V)-, (C + Nb)- and (C + Ta)-doped Y2Ti2O7 are potential visible-light-responsive photocatalysts for overall water splitting

Contact pattern of the CDD model.

(a) The mean (blue) and median (red) of the contact time ω influenced by the velocity v of agents in the CDD model. (b) The percentages of ω in different time ranges for the velocity v of agents in the CDD model. The blue line represents ω rc /v, the red line represents 0.5*rc /v ≤ ω rc /v, and the green line represents ω ≥ 4*rc/v. (c) The mean free time τ in the CDD model (solid line) and the CDD-NC model (dashed line) for different velocities.</p

Infection spreading in different <i>p</i>_<i>SE</i> and the basic reproduction number <i>R</i>_<i>0</i> influenced by <i>p</i>_<i>SE</i> and the velocity <i>v</i> of agents in the system.

The dynamic progress of the infection spreading when pSE = 1.0*10−4 (a) and pSE = 2.0*10−4 (b). Snapshots of Days 0, 20, and 40 are shown in order. (c) The influence of pSE and v of agents on R0 in the system. The points represent the calculated data, and the solid line represents the fitting curve to eliminate noise.</p