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Zinc polyoxometalate on activated carbon: an efficient catalyst for selective oxidation of alcohols with hydrogen peroxide 下载免费PDF全文
[PW11ZnO39]5? was immobilized on activated carbon and characterized using Fourier transform infrared, X‐ray diffraction, Brunauer–Emmett–Teller and elemental analysis techniques. Effective oxidation of various alcohols with hydrogen peroxide was performed in the presence of this catalyst. Easy separation of the catalyst from the reaction mixture, cheapness, high activity and selectivity, stability as well as retained activity in subsequent catalytic cycles make this supported catalyst suitable for small‐scale synthesis. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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Muhammad Usman Khan Muhammad Yasir Mehboob Riaz Hussain Zainab Afzal Muhammad Khalid Muhammad Adnan 《International journal of quantum chemistry》2020,120(22):e26377
The development of organic electron acceptor materials is one of the key factors for realizing high-performance organic solar cells (OSCs). Nonfullerene electron acceptors, compared to traditional fullerene acceptor materials, have gained much impetus owing to their better optoelectronic tunabilities and lower cost, as well as higher stability. Therefore, 5 three-dimensional (3D) cross-shaped acceptor materials having a spirobifullerene core flanked with 2,1,3-benzothiadiazole are designed from a recently synthesized highly efficient acceptor molecule SF(BR) 4 and are investigated in detail with regard to their use as acceptor molecules in OSCs. The density functional theory (DFT) and time-dependent DFT (TDDFT) calculations have been performed for the estimation of frontier molecular orbital (FMO) analysis, density of states analysis, reorganization energies of electron and hole, dipole moment, open-circuit voltage, photo-physical characteristics, and transition density matrix analysis. In addition, the structure-property relationship is studied, and the influence of end-capped acceptor modifications on photovoltaic, photo-physical, and electronic properties of newly selected molecules ( H1-H5 ) is calculated and compared with reference ( R ) acceptor molecule SF(BR) 4 . The structural tailoring at terminals was found to effectively tune the FMO band gap, energy levels, absorption spectra, open-circuit voltage, reorganization energy, and binding energy value in selected molecules H1 to H5 . The 3D cross-shaped molecules H1 to H5 suppress the intermolecular aggregation in PTB7-Th blend, which leads to high efficiency of acceptor material H1 to H5 in OSCs. Consequently, better optoelectronic properties are achieved from designed molecules H1 to H5 . It is proposed that the conceptualized molecules are superior than highly efficient spirobifullerene core-based SF(BR) 4 acceptor molecules and, thus, are recommended to experiments for future developments of highly efficient solar cells. 相似文献
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Md. Naziruddin Khan A. S. AI-Dwayyan Z. H. Zaidi 《中国物理快报》2006,23(9):2407-2410
Chrysene and 1.2-benzanthracene are successfully doped in a solid wax film and their vibrational spectra in gooo--400cm^-1 are discussed. The harmonic frequencies and relative intensities of both the molecules observed in the film are compared with theoretical values calculated by the density functional theory (DFT) model as well as with the previous experimental data. The effects on spectra due to change of matrix and some additional bands observed in the wax film are also reported. Excellent agreement in the spectral positions and strengths between the experiments and DFT values are found. 相似文献
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Polyvinyl alcohol (PVA)-based proton conducting polymer electrolytes have been prepared by the solution cast technique. The
conductivity is observed to increase from 10−9 to 10−4 S cm−1 as a result of orthophosphoric acid (H3PO4) addition. The plot of conductivity vs temperature shows that a phase transition occurred at 343 K in the sample PVA-33 wt%
H3PO4. The β-relaxation peak is observed at 313 K. The glass transition temperature of PVA-33 wt% H3PO4 is 343 K. Orthophosphoric acid seems to play a dual role, i.e., as a proton source and as a plasticizer. The ac conductivity
σ
ac = Aω
s was also calculated in the temperature range from 303 to 353 K. The conduction mechanism was inferred by plotting the graph
of s vs T from which the conduction mechanism for sample PVA-17 wt% H3PO4 was inferred to occur by way of the overlapping large polaron tunneling (OLPT) model and the conduction mechanism for the
sample PVA-33 wt% H3PO4 by way of the correlated barrier height (CBH) model. 相似文献
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In this paper, we use parametric quintic splines to derive some consistency relations which are then used to develop a numerical method for computing the solution of a system of fourth-order boundary-value problems associated with obstacle, unilateral, and contact problems. It is known that a class of variational inequalities related to contact problems in elastostatics can be characterized by a sequence of variational inequations, which are solved using some numerical method. Numerical evidence is presented to show the applicability and superiority of the new method over other collocation, finite difference, and spline methods. 相似文献
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M. Niyaz Khan 《国际化学动力学杂志》1991,23(7):561-566
The effects of the concentrations of LiCl, NaCl, KCl, CsCl, Na2CO3, BaCl2, and Me4NCl on the rates of reactions of hydroxide ion with ionized N-hydroxyphthalimide (NHP) at 30°C and in a H2O–MeCN solvent containing 98%, v/v, H2O reveal a nonlinear increase in observed rate constants with increase in salt concentrations. The observed rate constants are highly sensitive to the valence state of cations and almost insensitive to the valence state of anions of the salts. These observations are explained in terms of ion-pair formation between cations and NHP?. 相似文献