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Highly efficient H2 production over NiCo2O4 decorated g-C3N4 by photocatalytic water reduction
摘要： Herein, ternary nickel cobalt oxide (NiCo2O4) was firstly employed to increase the photocatalytic water reduction ability of g-C3N4. 17.5wt%-NiCo2O4/g-C3N4 shows excellent water splitting performance with a H2 production rate of 5480 μmol·h-1·g-1, which is extremely better than that of Co3O4, NiO, Pt modified g-C3N4. The quantum efficiency of 17.5wt%-NiCo2O4/g-C3N4 can reach 4.5% under 400 (±7.5) nm light irradiation. The greatly increased activity of 17.5wt%-NiCo2O4/g-C3N4 can be attributed to the richer active sites and the superior electrical performance provided by co-existing nickel and cobalt ions with multivalent state. Moreover, the activity of composite almost shows no significant weaken even after 20 h irradiation. A Z-scheme route was put forwarded for H2 production over NiCo2O4/g-C3N4 instead of the traditional p-n junction based on our study.
关键词： NiCo2O4,bimetallic complex,photocatalysis,hydrogen evolution
更新于2025-09-23 15:23:52
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Multi-configurational Ehrenfest simulations of ultrafast nonadiabatic dynamics in a charge-transfer complex
摘要： Multi-configurational Ehrenfest (MCE) approaches, which are intended to remedy the lack of correlations in the standard mean-field Ehrenfest method, have been proposed as coherent-state based ans?tze for quantum propagation [D. V. Shalashilin, J. Chem. Phys. 130, 244101 (2009)] and also as the classical limit of the variational Gaussian-based multiconfiguration time dependent Hartree (G-MCTDH) method [S. R?mer and I. Burghardt, Mol. Phys. 111, 3618 (2013)]. In the present paper, we establish the formal connection between these schemes and assess the performance of MCE for a coherent-state representation of the classical-limit subsystem. As a representative model system, we address the ultrafast, coherent charge transfer dynamics in an oligothiophene-fullerene donor-acceptor complex described by a two-state linear vibronic coupling model. MCE calculations are compared with reference calculations performed with the MCTDH method, for 10–40 vibrational modes. Beyond a dimensionality of 10 modes, it is shown that the correct representation of electronic coherence depends crucially on the sampling of initially unoccupied Gaussians.
关键词： nonadiabatic dynamics,Multi-configurational Ehrenfest,Gaussian wavepackets,MCTDH,ultrafast dynamics,charge-transfer complex
更新于2025-09-23 15:23:52
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A Reflectionless Discrete Perfectly Matched Layer
摘要： Perfectly Matched Layer (PML) is a widely adopted non-re?ecting boundary treatment for wave simulations. Reducing numerical re?ections from a discretized PML has been a long lasting challenge. This paper presents a new discrete PML for the multi-dimensional scalar wave equation which produces no numerical re?ection at all. The re?ectionless discrete PML is discovered through a straightforward derivation using Discrete Complex Analysis. The resulting PML takes an easily-implementable ?nite di?erence form with compact stencil. In practice, the discrete waves are damped exponentially in the PML, and the error due to domain truncation is maintained at machine zero by a moderately thick PML. The numerical stability of the proposed PML is also demonstrated.
关键词： Perfectly matched layers,absorbing boundary,scalar wave equation,discrete complex analysis
更新于2025-09-23 15:23:52
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-doped two-dimensional semiconductor quantum wells
摘要： We present a theoretical study of photoabsorption in n-doped two-dimensional (2D) and quasi-2D semiconductors that takes into account the interaction of the photocreated exciton with Fermi-sea (FS) electrons through (i) Pauli blocking, (ii) Coulomb screening, and (iii) excitation of FS electron-hole pairs—that we here restrict to one. The system we tackle is thus made of one exciton plus zero or one FS electron-hole pair. At low doping, the system ground state is predominantly made of a 'trion-hole'—a trion (two opposite-spin electrons plus a valence hole) weakly bound to a FS hole—with a small exciton component. As the trion is poorly coupled to photon, the intensity of the lowest absorption peak is weak; it increases with doping, thanks to the growing exciton component, due to a larger coupling between two-particle and four-particle states. Under a further doping increase, the trion-hole complex is less bound because of Pauli blocking by FS electrons, and its energy increases. The lower peak then becomes predominantly due to an exciton dressed by FS electron-hole pairs, that is, an exciton-polaron. As a result, the absorption spectra of n-doped semiconductor quantum wells show two prominent peaks, the nature of the lowest peak turning from trion-hole to exciton-polaron under a doping increase. Our work also nails down the physical mechanism behind the increase with doping of the energy separation between the trion-hole peak and the exciton-polaron peak, even before the anticrossing, as experimentally observed.
关键词： Fermi sea,trion-hole complex,exciton-polaron,photoabsorption,Pauli blocking,n-doped semiconductors,Coulomb screening
更新于2025-09-23 15:23:52
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Synthesis and photoluminescence properties of different structural cuprous complexes regulated by benzoxazole ligands and halogen/pseudohalide ions
摘要： Reaction of 2-(2’-pyridyl)benzoxazole (2-PBO), 2-(4’-pyridyl)benzoxazole (4-PBO) and 2,2-(1,4-butanediyl)bis-1,3-benzoxazole (BBO) ligands with CuX (X = I, Br, SCN) afforded a binuclear copper(I) complex [Cu(2-PBO)(μ2-I)]2 (1) and three copper(I) coordination polymers [Cu4(4-PBO)4(μ3-I)4]n (2), {[Cu(4-PBO)(μ3-SCN)]2}n (3) and {[Cu(BBO)(μ2-Br)]2}n (4). The structural analysis revealed that the all copper(I) ions are four-coordinated and the geometric structure around the central copper(I) atom possessing slightly distorted tetrahedral geometry in complexes 1-4. Halogen or pseudohalide ions can not only act as counter anions, but also as ligands participation in coordination when the cuprous ion coordination sites are not saturated. Due to the different coordination modes of the benzoxazole ligands, in order to satisfy the tetra-coordination of cuprous ions, halogen or pseudohalide ions adopt μ2 and/or μ3-bridging modes to synergistically complete coordination. Photoluminescence investigation show that complexes 1, 3 and 4 have two emission peaks, the high energy band peak is attributed to MLCT[d10(Cu)→π*] and XMCT, the low energy band peak is caused by the 3CC emission. This may be due to the presence of μ2-X (X=I, Br, S) in these complexes. However complex 2 only had one emission peak, which may be attributed to MLCT[d10(Cu)→π*] and XMCT.
关键词： Cuprous complex,Charge-transfer,Photoluminescence,Crystal structure,Benzoxazole
更新于2025-09-23 15:23:52
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Application of the hybrid complex variable method to the analysis of a crack at a piezoelectric-metal interface
摘要： A plane strain problem for an electrically conducting interface crack between linear transversely isotropic piezoelectric and isotropic elastic conductor materials under remote mechanical loading is considered. The attention is focused on a hybrid complex variable method which combines the Stroh formalism for piezoelectric materials with the Muskhelishvili formalism for conducting isotropic elastic materials. This method is illustrated in detail for the open crack model and the contact zone crack model. Using special presentations of mechanical quantities via sectionally analytic functions, a combined Dirichlet–Riemann and Hilbert boundary value problem is formulated and solved analytically. Stress intensity factors as well as the crack tip energy release rate are found in a clear analytical form. Furthermore, transcendental equations for the determination of the realistic contact zone length and the location of the first interpenetration point have been obtained. A significant influence of the external mechanical loading on the crack opening and the stresses as well as the contact zone and interpenetration region lengths is observed. The dependencies of the mentioned values on the intensities of the mechanical loading are presented in tables and associated diagrams.
关键词： electrically conducting interface crack,Piezoelectric-metal joint,contact zone,complex variable method
更新于2025-09-23 15:23:52
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GENERATION OF COMPLEX SOURCE POINT EXPANSIONS FROM RADIATION INTEGRALS (Invited Paper)
摘要： This paper discusses methods for expanding fields radiated by arbitrary sources enclosed by a certain minimum sphere in terms of Complex Source Point (CSP) beams. Two different approaches are reviewed; the first one is based on a spectral radiation integral, where the Fourier-spectrum is obtained by far field matching. The second approach consists of two steps: first, the equivalence principle is applied to a sphere enclosing the real sources, and a continuous equivalent electric current distribution is obtained in terms of spherical waves; then, the continuous current is extended to complex space and its SW components are properly filtered and sampled to generate the discrete set of CSPs. In both cases, the final result is a compact finite series representation with a number of terms that matches the degrees of freedom of arbitrary radiated fields; it is particularly efficient when the fields are highly directional and the observation domain is limited to a given angular sector. The fact that the CSPs rigorously respect Maxwell's equations ensures the validity of the expansion from near to far zone and allows one to incorporate the CSP representation in a generalized admittance matrix formalism for the analysis of complex problems.
关键词： CSP beams,field expansion,degrees of freedom,generalized admittance matrix,spectral matching,radiation integrals,Complex Source Point,spherical waves
更新于2025-09-23 15:23:52
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Harnessing the synergy between upconverting nanoparticles and lanthanide complexes in a multi-wavelength responsive hybrid system
摘要： We prepared a hybrid system composed of a continuous film of dinuclear lanthanide complex [Ln2bpm(tfaa)6] (Ln = Tb or Eu) and upconverting nanoparticles (UCNPs) using a straightforward drop-cast methodology. The system displayed visible emission under near-infrared (NIR) excitation, simultaneously stemming from sub-10-nm UCNPs and [Ln2] complexes, the latter species being otherwise directly excitable only using UV-blue radiation. In light of the results of steady-state – including power-dependent – and time-resolved optical measurements, we identified the radiative, primarily ligand-mediated nature of the energy transfer from Tm3+ ions in the UCNPs-to-Ln3+ ions in the complexes. Hyperspectral mapping and electron microscopy observations of the surface of the hybrid system confirmed the continuous and concomitant distribution of UCNPs and lanthanide complexes over the extensive composite films. Key features of the hybrid system are the simultaneous UV-blue and NIR light harvesting capabilities and their ease of preparation. These traits render the presented hybrid system a formidable candidate for the development of photoactivated devices capable to operate under multiple excitation wavelength and to transduce the absorbed light into narrow, well-defined spectral regions.
关键词： hybrid system,complex,energy transfer,lanthanide,films,upconverting nanoparticles,hyperspectral imaging
更新于2025-09-23 15:23:52
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Structural and Optical Properties of CeO2 Nanoparticles Synthesized by Modified Polymer Complex Method
摘要： Ceria nanoparticles (Ceria-NPs) were synthesized using a modified polymer complex method and their structural and optical properties were evaluated. The solids were heated at 550 °C and characterized using Raman, UV–Vis absorption, diffuse reflectance, X-ray photoelectron and photoluminescence spectroscopies, X-ray diffraction (XRD) and scanning and transmission electron microscopy. The primary particles obtained presented a size of ~ 10 nm. The XRD indicated that CeO2 was the only crystalline phase. From the UV–Vis and diffuse reflectance spectra, energy values of 3.8 eV and 3.4 eV were obtained, values that can be associated with band—band electronic transitions and/or with those that involve ionized states located within the gap caused by defects and isolated atoms of Ce3+. Photoluminescence spectra reiterated the existence of localized states in the gap. Raman spectra revealed the existence of peroxide (O2^2-) and superoxide (O2^-) over the surface of the ceria-NPs. The XPS results indicated that the concentrations of Ce3+ and Ce4+ were ～ 20.5% and ～79.5% respectively, and that the stoichiometry of oxygen was 1.9 per atom of Ce. The results obtained from the characterization of CeO2-NPs synthesized make it as promising material for environmental remediation, biomedicine, gas sensing and optoelectronic applications.
关键词： Modified polymer complex,Structural properties,Ceria-NPs,Optical properties,Synthesis
更新于2025-09-23 15:23:52
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Recovering distance information in spectral domain interferometry
摘要： This work evaluates the performance of the Complex Master Slave (CMS) method, that processes the spectra at the interferometer output of a spectral domain interferometry device without involving Fourier transforms (FT) after data acquisition. Reliability and performance of CMS are compared side by side with the conventional method based on FT, phase calibration with dispersion compensation (PCDC). We demonstrate that both methods provide similar results in terms of resolution and sensitivity drop-off. The mathematical operations required to produce CMS results are highly parallelizable, allowing real-time, simultaneous delivery of data from several points of different optical path differences in the interferometer, not possible via PCDC.
关键词： distance measurement,spectral domain interferometry,optical coherence tomography,dispersion compensation,phase calibration,Complex Master Slave,Fourier transforms
更新于2025-09-23 15:23:52