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Synthesis and multimethodological characterization of neodymium substituted nickel tungstates and molybdates solid solution Ni Ndx (W,Mo)O4, (0?≤?x?≤?0.2)
摘要： New series of neodymium substituted nickel tungstates and molybdates NiNdxM’O4 (M’=W,Mo and x=0%, 10%, 20%) were synthesized by standard solid state route at high temperature T=1000°C.These materials, were characterized by powder X-Ray diffraction technique (XRD), which confirmed that both series of tungstates and molybdates crystallized in monoclinic structure with space groups(P2/c, C2/m) respectively and behaved as a quasi-ideal solid solution. Scanning Electron Microscopy (SEM) experiments showed the presence of grains with irregular sizes developed within larger aggregations, while EDS semi-quantitative analyses confirmed the nominal compositions for all the phases.Active vibration modes were investigated by Fourier Transform InfraRed (FTIR) and Raman techniques, the group theoretical calculation predicted 36 vibrational modes. The presence of characteristic frequencies assigned to components ?1 and ?3 confirmed the existence of WO6 and MoO6 polyhedra in the structures, non-vibrational bands appearing in Raman spectra were attributed to laser-excited luminescence of neodymium element.
关键词： solid state reaction,vibrational properties,neodymium,nickel tungstates,X-ray diffraction,nickel molybdates
更新于2025-09-10 09:29:36
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Regulating the Optoelectronic Properties of Nickel Dithiolene by the Substituents: A Theoretical Study
摘要： Dithiolene-based complexes show great potential to be applied as materials for organic optoelectronic devices. In this study, we theoretically designed a series of complexes based on nickel dithiolene and its substituted derivatives, the optoelectronic properties of which were comparatively studied by density functional theory (DFT)/time-dependent density functional theory (TD-DFT). The results show that the charge injection property of nickel dithiolene complexes can be significantly improved with introduction of electron-withdrawing groups. The charge transportation property of nickel dithiolene depends on the conjugation degree of the system. The energy gaps between highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) are determined by the substituents, which makes the maximum absorption wavelength red-shift from the visible to the near-infrared (NIR) region. The electron density difference graph shows that the electron transition from the ground state to the first excited state is assigned to π-π* transition mainly from HOMO to LUMO. The regularity of substituent effect revealed by us in this study will shed light on the application of nickel dithiolenes as potential optoelectronic materials.
关键词： substituents,DFT,nickel dithiolene,optoelectronic properties
更新于2025-09-10 09:29:36
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Tracing the Origin of Visible Light Enhanced Oxygen Evolution Reaction
摘要： Hybrid nanostructures with a plasmonic core and catalytic shell often show significantly enhanced catalytic efficiency under illumination of specific frequency. Excitation of localized surface plasmonic resonance on plasmonic metals under illumination can generate hot electrons that assist in the catalytic reaction. However, the correlation between the microstructural geometry, dielectric environment, internal energy flow in the hybrid structure, and the chemical reaction rate is so far not clear. Here, a composite with a plasmonic Au metal yolk and a nearly transparent Ni3S2 shell is designed to maximize the absorption of incident light by forming strong localized surface plasmonic resonance at the yolk as predicted by 3D finite element method. The incoming photoenergy is dominantly dissipated on the shell by forming electron–hole pairs, leading to higher energy flow rate for oxygen evolution reaction. The overpotential is 252 mV at 10 mA cm?2 and the catalytic activity of Au@Ni3S2 achieves ca. 85-fold that of pure Ni3S2 under illumination and surpasses the commercial IrO2 catalyst. The study opens the door of exploration of highly effective hybrid composite catalysts for energy applications.
关键词： gold,localized surface plasmonic resonance (LSPR),nickel,photo-electrochemistry,electrocatalysts
更新于2025-09-10 09:29:36
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Comparative activity of aqueous dispersions of CdS nanocrystals stabilized by cationic and anionic polyelectrolytes in photocatalytic hydrogen production from water
摘要： The results of a study on the photocatalytic activity of aqueous dispersions of Ni-doped CdS nanocrystals (NCs) covered with an amphiphilic polyelectrolyte (PE) shell, i.e., a polycation (NC-PC) or polyanion (NC-PA), are presented for the first time. The H2 evolution rate measured under identical conditions served as a measure of activity. The NC-PC and NC-PA samples were characterized by similar PE content (~40%) and monomodal size distribution. According to our calculations based on the NC dimensions and lattice parameters, about one macromolecule of the PE is required to stabilize one NC. The average hydrodynamic diameter of the NC-PC was found to be 1.5 times larger than that of the NC-PA due to the difference between their chemical structures and different abilities of ionogenic groups to dissociate. The photocatalytic activity of the PE-stabilized CdS nanocrystals was significantly influenced by the type of the PE, while the H2 evolution rate depended on the reducing medium used during the process. When the medium contained Na2S or when the PE-stabilized NCs were pre-treated with Na2S, the effect of the shell type was more pronounced and the activity of NC-PA was 2 to 14 times higher than that of NC-PC.
关键词： polyelectrolytes,nanocrystals,photocatalysis,cadmium sulfide,hydrogen evolution reactions,nickel
更新于2025-09-10 09:29:36
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Characteristics of NiO films prepared by atomic layer deposition using bis(ethylcyclopentadienyl)-Ni and O2 plasma
摘要： Plasma-enhanced atomic layer deposition (PEALD) is well-known for fabricating conformal and uniform films with a well-controlled thickness at the atomic level over any type of supporting substrate. We prepared nickel oxide (NiO) thin films via PEALD using bis(ethylcyclopentadienyl)-nickel (Ni(EtCp)2) and O2 plasma. To optimize the PEALD process, the effects of parameters such as the precursor pulsing time, purging time, O2 plasma exposure time, and power were examined. The optimal PEALD process has a wide deposition-temperature range of 100-325 oC and a growth rate of 0.037±0.002 nm per cycle. The NiO films deposited on a silicon substrate with a high aspect ratio exhibited excellent conformality and high linearity with respect to the number of PEALD cycles, without nucleation delay.
关键词： Thin Film,Nickel Oxide,Plasma-enhanced Atomic Layer Deposition,Bis(ethylcyclopentadienyl)-nickel,Atomic Layer Deposition
更新于2025-09-09 09:28:46
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Epitaxial growth of undoped and Li-doped NiO thin films on α–Al2O3 substrates by mist chemical vapor deposition
摘要： Undoped and Li-doped NiO thin films were grown on α-Al2O3 (0001) substrates by mist chemical vapor deposition. Both undoped and Li-doped NiO thin films grew bi-epitaxially on the substrates with crystallographic orientation relationships of NiO(111)[ˉ110]?||?α-Al2O3(0001)[01ˉ10] and NiO(111)[1ˉ10]?||?α-Al2O3(0001)[01ˉ10]. In the Li-doped NiO thin film, a periodic structure was observed, in accordance with a mirror-symmetrical oxygen layer on the terraces of the substrate. Both undoped and Li-doped NiO thin films exhibited high transmittance (>80%) in the visible-light region and optical bandgaps of 3.7–3.8 eV. The undoped NiO thin film showed insulating properties and a resistivity of 106 ??cm or higher. In contrast, the Li-doped NiO thin films had resistivities of 101–105 ??cm, depending on the Li precursor concentration. Furthermore, they exhibited positive Seebeck coefficients, indicating their p-type conductivity. These results indicate that Li dopants effectively act as acceptors in NiO thin films.
关键词： A3.Mist CVD,B1.Nickel oxide,B2.Wide bandgap oxide semiconductor,B1.Li-doped nickel oxide
更新于2025-09-09 09:28:46
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Selective Photocatalytic C-F Borylation of Polyfluoroarenes by Rh/Ni Dual Catalysis Providing Valuable Fluorinated Arylboronate Esters
摘要： A highly selective and general photocatalytic C-F borylation protocol that employs a rhodium biphenyl complex as a triplet sensitizer and the nickel catalyst [Ni(IMes)2] (IMes = 1,3-dimesitylimidazolin-2-ylidene) for the C-F bond activation and defluoroborylation process is reported. This tandem catalyst system operates with visible (blue, 400 nm) light and achieves borylation of a wide range of fluoroarenes with B2pin2 at room temperature in excellent yields and with high selectivity. Direct irradiation of the intermediary C-F bond oxidative addition product trans-[NiF(ArF)(IMes)2] leads to very fast decomposition when B2pin2 is present. This destructive pathway can be bypassed by indirect excitation of the triplet states of the nickel(II) complex via the photoexcited rhodium biphenyl complex. Mechanistic studies suggest that the exceptionally long-lived triplet excited state of the Rh biphenyl complex used as the photosensitizer allows for efficient triplet energy transfer to trans-[NiF(ArF)(IMes)2], which leads to dissociation of one of the NHC ligands. This contrasts with the majority of current photocatalytic transformations, which employ transition metals as excited state single electron transfer agents. We have previously reported that C(arene)-F bond activation with [Ni(IMes)2] is facile at room temperature, but that the transmetalation step with B2pin2 is associated with a high energy barrier. Thus, this triplet energy transfer ultimately leads to a greatly enhanced rate constant for the transmetalation step and thus for the whole borylation process. While addition of a fluoride source such as CsF enhances the yield, it is not absolutely required. We attribute this yield-enhancing effect to (i) formation of an anionic adduct of B2pin2, i.e. FB2pin2-, as an efficient, much more nucleophilic {Bpin-} transfer reagent for the borylation/transmetalation process, and/or (ii) trapping of the Lewis acidic side product FBpin by formation of [F2Bpin]- to avoid the formation of a significant amount of NHC-FBpin and consequently of decomposition of {Ni(NHC)2} species in the reaction mixture.
关键词： C-F Bond Activation,Nickel Complex,N-Heterocyclic Carbene,Borylation,Aryl Boronate,Photocatalysis,Rhodium Complex,Fluoroarene
更新于2025-09-09 09:28:46
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Solvothermal Syntheses, Crystal Structures, and Photocatalytic Properties of Iodoplumbate Hybrids with Ni(II) Complex Templates
摘要： Organic–inorganic iodoplumbate hybrids [Ni(en)2]2Pb3I10 (1), [Ni(en)3]Pb2I6 (2) (en = ethylenediamine), [Ni(dien)2]Pb2I6?H2O (3) (dien = diethylenetriamine), [Ni(14-TMC)][PbI3]2?DMF (4) and [Ni(14-TMC)]2[Pb5I14(DMSO)2] (5) (14-TMC = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane) were prepared using different Ni(II) complex cation as structural directing agents under solvothermal conditions. Compounds 1?4 consist of 1-D [Pb3I10 4–]n and [Pb2I6 2–]n polymeric anions constructed by PbI6 octahedra via corner-, edge- or face-sharing, respectively. The novel organic hybrid iodoplumbate anion [Pb5I14(DMSO)2 4–]n in 5 is composed of PbI6 and PbI5O octahedra via edge- and face-sharing. The formation of polymeric iodoplumbate anions in 1?5 indicates different structure-directing effect of the Ni(II) complex cations with various polyamino ligands under appropriate reaction and crystallization conditions. Compounds 1?5 exhibit tunable band gaps varying in the range of 2.18?2.61 eV. Compounds 4 and 5 are more effective than 1 and 3 in the photocatalytic degradation of methylene blue.
关键词： Photocatalytic property,Organic-inorganic hybrid,Nickel,Iodoplumbate,Templating synthesis
更新于2025-09-09 09:28:46
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An investigation on electroless nickel coating on yttria stabilized zirconia nanoparticles via single step surface activation methods
摘要： Metal coated ceramic nanopowders have a considerable potential for many fields of applications. Here, electroless coating of pure nickel onto yttria-stabilized zirconia nanoparticles is studied. We introduce a single step method to activate ceramic nanoparticles surface to reduce complexities of electroless coating on ceramic nanoparticles by conventional double step pre-treatments. X-ray diffraction and electron diffraction patterns beside transmission electron microscopy images are used to analyze the coated nanoparticles. We observe that palladium hydroxide acts as a catalyst for electroless nickel reaction like palladium and the ceramic nanopowders surface is effectively activated for electroless reaction by simpler single step activation methods. Atomic absorption spectroscopy results show that the performance of electroless reaction is not enhanced by increase in catalyst amount. Also, relative changes in amount of deposited nickel are investigated via magnetization curves of the coated particles. The vibrating sample magnetometery results demonstrate the magnetic behavior of the processed particles can be modified by deposited nickel amount.
关键词： Catalysis,Nickel,coating,Palladium,Electroless,YSZ nanopowder
更新于2025-09-09 09:28:46
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Nickel foam–caged Ag-Au bimetallic nanostructure as a highly rugged and durable SERS substrate
摘要： A three-dimensional nickel foam (NF) caging Ag-Au bimetallic nanostructure (Ag-Au@NF) has been demonstrated as a highly rugged and sensitive surface-enhanced Raman scattering (SERS) substrate. The main concept employed in designing this substrate was the protection of SERS-active nanostructures by holding them within a sturdy frame. For this purpose, NF was readily chosen as a strong porous frame to secure the internal nanostructures owing to its excellent structural strength and ability to easily incorporate analytes due to its porous structure. The next issue was the construction of stable and SERS-e?cient nanostructures within the NF frame. To meet this need, an Ag-Au bimetallic nanostructure was chosen, combining the high SERS e?ciency of Ag and the good surface stability of Au. To fabricate the Ag-Au nanostructure, ?rst a Sn-Ag alloy was constructed on the NF frame by means of electrodeposition (producing Sn-Ag@NF) and then Sn was selectively leached from the alloy by means of free corrosion in NaOH solution (producing Ag@NF). This selective leaching was adopted to make the surface rough to enhance the SERS e?ciency in the ?nal substrate. Finally, Au was incorporated into the Ag@NF by means of a galvanic replacement reaction (producing Ag-Au@NF). The use of Ag-Au@NF enabled identi?cation of rhodamine 6G at concentrations as low as 0.1 nM. The Ag-Au@NF substrates were rugged, showing small Raman signal drops after 100 cycles of sandpaper abrasion or 30 min of sonication. Also, the signal decrease was only 4.26% upon 3 days of exposure to ambient air without special care. Overall, the Ag-Au@NF developed herein shows practical merits for adoption in routine and ?eld SERS analyses.
关键词： Surface enhanced Raman scattering,High durability,Ag-Au nanostructure,Porous structure,Nickel foam
更新于2025-09-09 09:28:46