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- South China Normal University
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- Nanchang Hangkong University
- State Grid Corporation of China
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Yb <sup>3+</sup> /Ln <sup>3+</sup> /Mn <sup>4+</sup> (Ln = Er, Ho, and Tm) doped Na <sub/>3</sub> ZrF <sub/>7</sub> phosphors: oil–water interface cation exchange synthesis, dual-modal luminescence and anti-counterfeiting
摘要： Efficient dual-modal luminescence is highly desired for applications in high security anti-counterfeiting. In the present work, Yb3+/Ln3+/Mn4+ (Ln = Er, Ho, and Tm) tri-doped Na3ZrF7 phosphors were fabricated via oil–water interface cation exchange using Yb3+/Ln3+:Na3ZrF7 as the exchanging hosts. The as-prepared products exhibited typical Mn4+ red down-shifting luminescence under UV light excitation and Er3+ red, Ho3+ yellow and Tm3+ near-infrared multi-color upconversion emissions under 980 nm laser excitation. The Mn4+ dopants in the Na3ZrF7 host experienced strong crystal-field strength Dq of 3.63 and showed superior thermal stability with up to 90% of the initial emission intensity retained at 448 K. Steady-state and time-resolved emission spectra verified that there was no detrimental energy transfer interaction between Mn4+ and Ln3+, enabling bright and eye-visible bi-functional emissions for the present products. As a consequence, the as-prepared phosphors were demonstrated to be applicable in anti-counterfeiting by a proof of concept experiment of fluorescent labeling for specially designed patterns.
关键词： phosphors,upconversion,anti-counterfeiting,cation exchange,dual-modal luminescence
更新于2025-11-20 15:33:11
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Synthesis, Morphology, Optical and Electrical Properties of Cu <sub/> 1? <i>x</i> </sub> Fe <sub/><i>x</i> </sub> O Nanopowder
摘要： The pure and Fe-doped CuO nanoparticles of the series Cu1?xFexO (x = 0, 0.027, 0.055, 0.097 and 0.125) were synthesized by a simple low temperature sol–gel method. Synthesized samples were characterized by a series of techniques including Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive X-ray electron spectroscopy (EDX), Diffuse Reflectance Spectroscopy (DRS), Fourier Transform Infrared Spectroscopy (FTIR), Hall Effect Set-up and Current–Voltage (I–V) characteristics. FESEM analysis shows formation of disc type structure increasing in grain size with Fe concentration in CuO. EDX confirmed the incorporation of iron in CuO. FTIR results of pure and Fe doped CuO samples have confirmed the formation of monoclinic CuO. The optical band gap estimated using Diffuse Reflectance Spectroscopy (DRS) shows the increment in the band gap values with Fe substitution. The Hall measurements show predominantly p-type conduction in all the samples and carrier densities decrease with increased Fe substitution. I–V characteristics of pure and Fe doped CuO nanoparticles show rectification behaviour of Schottky diodes.
关键词： Defect States,Hall Effect,Schottky Diode,Cation Vacancies,Fe-Substituted CuO
更新于2025-11-19 16:56:35
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Ultra-small colloidal heavy-metal-free nanoplatelets for efficient hydrogen generation
摘要： Metal chalcogenide semiconducting nanoplatelets exhibit a broad absorption spectrum, as well as thickness-dependent optical and electronic properties. As such, they may be used as building blocks in a variety of optoelectronic devices. The direct synthesis of heavy-metal-free ultra-small sized nanoplatelets is still challenging, due to the inherent limits in existing synthetic approaches. Here, we report an efficient template-assisted cation-exchange route to synthesize heavy metal free metal chalcogenide nanoplatelets that are optically active in the near infrared. The SnSe nanoplatelets, whose lateral dimension is 6-10 nm, exhibit a quantum yield of 20%. The nanoplatelets are applied as light absorbers in a photoelectrochemical (PEC) system for hydrogen generation, leading to a saturated photocurrent density of 7.4 mA/cm2, which is a record for PEC devices using heavy metal-free colloidal quantum dots or nanoplatelets under identical measurement conditions. Our results indicate that quasi-zero-dimensional SnSe nanoplatelets hold great potential as efficient light absorbers for emerging optoelectronic technologies.
关键词： nanoplatelets,cation exchange,optoelectronic technologies,SnSe,hydrogen generation
更新于2025-11-19 16:51:07
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Stable, Color-Tunable 2D SCN-Based Perovskites: Revealing the Critical Influence of Asymmetric Pseudo-Halide on Constituent Ions
摘要： Two-dimensional (2D) layered perovskites (An+1BnX3n+1, n = 1, 2, …) have lately attracted significant research interest because of their enhanced ambient stability comparing to the conventional 3D counterparts. Beside the common A-site cation engineering, using an asymmetric pseudo-halide, SCN, anion in X-site anion has been recently proven as another effective approach to constitute 2D perovskite. Among them, 2D (MA)2Pb(SCN)2I2 was most widely investigated and honored as a promising material owing to its decent optoelectronic properties; however, its poor stability arouses concerns from the recent researches. In this study, a systematical composition engineering of A2Pb(SCN)2X2 (A= FA+, MA+, Cs+ and X= Br-, I-) was conducted. Our results revealed that linear SCN- anion may dictate critical restrictions on the constituent ions of its derived 2D framework (PbX4(SCN)2), which has not been extensively discussed yet. We demonstrated that using a smaller Cs+ cation can afford a more favorable 2D structure compared with the MA+ cation. Cs2Pb(SCN)2I2 was revealed to possess improved stability and photo-response compared to (MA)2Pb(SCN)2I2. Interestingly, Cs2Pb(SCN)2I2 and (MA)2Pb(SCN)2I2 seem to possess distinct electronic band structures as indicated by their discrepant photoluminescence spectra, for which the former exhibits a rather intense singlet emission at room temperature, as opposed to the latter having a dominant emission associated with triplet or defective states. Furthermore, using a smaller Cs+ cation also enables facile replacement of smaller halide anion. A series of mix-halide 2D Cs2Pb(SCN)2(I1-xBrx)2 (x = 0, 1/3, 1/2, 2/3, 1) with variant vivid color was explored by both calculation and experimental efforts to corroborate the further enhanced stability when x value increases. The results revealed in this work might be inherent trait of 2D SCN-based perovskites and also unveil that all inorganic 2D Cs2Pb(SCN)2X2 perovskite system is a promising class of material with decent stability and color-tunability, deserving further explorations.
关键词： stability,Cs cation,pseudo-halide,SCN- anion,color-tunability,2D perovskite
更新于2025-11-14 17:04:02
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Shedding light on the electronic structure of [Ru(η6-C16H16)(NH3)3]2+ complex: a computational insight
摘要： Ruthenophanes have been recognized as potential candidates to the design of electrically conducting polymers, particularly due to their electrochemical, structural, and spectroscopic properties. The comprehension and rationalization of the metal–ligand interaction is fundamental to pave the way for future applications as the design of new conducting materials. For that reason, this investigation sheds light on the electronic details behind the cation–π interactions present in ruthenophanes by using [Ru(η6-C16H16)(NH3)3]2+ as a model. Zeroth-order symmetry-adapted perturbation theory (SAPT0) shows the interaction Ru(II)–[2.2]paracyclophane with a predominant covalent character. However, the hapticity analysis of [2.2]paracyclophane shows only two predominantly covalent Ru–C bonds, as highlighted by the total energy density, H(r), in the bond critical point (BCP) obtained from quantum theory of atoms in molecules (QTAIM) method, and by second-order stabilization energy, (cid:4)E(2), related to the processes: π C–C → dσ or dπ Ru, achieved in the natural bond orbital (NBO) method. The other two Ru–C chemical bonds show a largely electrostatic character, as can be visualized from the delocalization index, DI, between the electron basins in the electron localization function (ELF) method. Remarkably, the interacting quantum atoms (IQA) method showed practically the same value of the total interaction energy, EAB int , between Ru and these C atoms and, then, corroborates the hapticity four of the ligand: [2.2]paracyclophane. Source function distribution presents a correlation with the electronic interactions between different groups in [Ru(η6-C16H16)(NH3)3]2+.
关键词： Ru-C chemical bond,Cation–π interaction,ELF,IQA,SAPT,Hapticity
更新于2025-09-23 15:23:52
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Activated carbons with adsorbed cations as photocatalysts for pollutants degradation in aqueous medium
摘要： Oxidized activated carbon (AC) based on commercial coconut-shell carbon Aquacarb 607C has been prepared. This AC has micro-mesoporous structure and contains surface carboxyl and phenol/enol groups. Cu- and Co-containing ACs have been synthesized via ion-exchange in acid medium. According to potentiometric titration and XPS data, cation-exchanged forms of AC contain about 0.5% of metal ions. Such cation-containing ACs possess narrowed band gap compared oxidized AC as it is observed for doped oxides. Oxidized and cation-containing ACs have been tested as catalysts in photodegradation of dyes and phenol under UV- and visible irradiation. Initial oxidized AC is photoactive toward rhodamine B and methyl orange under UV illumination but inactive under visible light. For the first time it is shown that cation-exchanged forms of AC have enhanced activity towards rhodamine B, methyl orange and phenol in both UV and visible region. Therefore, the principal possibility of improving the photocatalytic properties of AC by introducing a minimal amount of copper and cobalt cations is shown.
关键词： Cation-exchanged forms,Decolourisation and mineralization,UV and visible irradiation,Activated carbon,Photocatalytic degradation
更新于2025-09-23 15:23:52
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Copper’s Role in the Photoluminescence of Ag1?xCuxInS2 Nanocrystals, from Copper-Doped AgInS2 (x ~ 0) to CuInS2 (x = 1)
摘要： A series of Ag1?xCuxInS2 nanocrystals (NCs) spanning from 0 ≤ x ≤ ~1 was synthesized by partial cation exchange to identify copper’s contributions to the electronic structure and spectroscopic properties of these NCs. Discrete mid-gap states appear above the valence band (VB) upon doping AgInS2 NCs with Cu+ (small x). Density functional theory (DFT) calculations confirm that these mid-gap states are associated with the 3d valence orbitals of the Cu+ impurities. With increasing x, these impurity d levels gradually evolve to become the VB edge of CuInS2 NCs, but the highest-occupied orbital's description does not change significantly across the entire range of x. In contrast with this gradual evolution, Ag1?xCuxInS2 NC photoluminescence shifts rapidly with initial additions of Cu+ (small x) but then becomes independent of x beyond x > ~0.20, all the way to CuInS2 (x = 1.00). Data analysis suggests small but detectable hole delocalization in the luminescent excited state of CuInS2 NCs, estimated by Monte Carlo simulations to involve at most about four copper ions. These results provide unique insights into the luminescent excited states of these materials and they reinforce the description of CuInS2 NCs as “heavily copper-doped NCs” in which photogenerated holes are rapidly localized in copper 3d-based orbitals.
关键词： silver indium sulfide,nanocrystal,cation exchange,Copper indium sulfide,copper-doped,photoluminescence
更新于2025-09-23 15:23:52
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Charged polariton luminescence from an organic semiconductor microcavity
摘要： Strong coupling light to polaron optical transitions in an organic semiconductor microcavity leads to an unusual class of polariton that possesses a net charge. This species may offer a range of technologically-useful optoelectronic properties but has thus far only been observed in passive reflectivity measurements. Here, we report room-temperature photoluminescence from both upper and lower branch polaron polariton states that originate from hole excitations in a p-doped 4,4’-cyclohexylidenebis[N,N-bis(4-methylphenyl)benzenamine] (TAPC) microcavity. Our observations under non-resonant excitation are in good agreement with classical dipole emission modeling, which suggests that polariton states in this system are populated radiatively via fluorescence from the polaron excited state reservoir. These results constitute one of the first observations of polaron luminescence from an organic semiconductor thin film and are an important prerequisite for realizing a charged polariton condensate.
关键词： strong coupling,Polaron,fluorescence,cation
更新于2025-09-23 15:22:29
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Mixed-Cation Mixed-Metal Halide Perovskites for Photovoltaic Applications: A Theoretical Study
摘要： Perovskite solar cells based on multiple cations have shown excellent optoelectronic properties with high power conversion efficiency. Herein, the structural, electronic, and optical properties of mixed-cation mixed-metal perovskites MA1?xCsxPb0.25Sn0.75I3 were studied by employing the first-principles calculations for the first time. Our calculated results reveal that these perovskite materials possess direct band gaps in the range of 1.0?1.3 eV. Moreover, these compounds show excellent photovoltaic performance in terms of strong optical absorption coefficients compared with MAPbI3. Particularly, they also exhibit good structural stability and decrement of lead content. These results demonstrated that mixed-cation mixed-metal perovskites may be potential candidates for high-efficiency light-absorbing materials.
关键词： mixed-cation mixed-metal perovskites,electronic properties,optical properties,first-principles calculations,photovoltaic applications,structural stability
更新于2025-09-23 15:21:01
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Adsorption and Cation Exchange Behavior of Zinc Sulfide (ZnS) on Mesoporous TiO2 Film and Its Applications to Solar Cells
摘要： Zinc sulfide (ZnS) was deposited onto the surface of mesoporous TiO2 film by a typical successive ionic layer adsorption and reaction (SILAR) process. By inducing a spontaneous cation exchange between ZnS and a target cation (Pb2+, Cu2+, Ag+, or Bi3+) dissolved in chemical bath when they are in contact, it was demonstrated successfully that white translucent ZnS on the substrate could be changed to brown-colored new metal chalcogenides and the amount of ZnS deposited originally by different conditions could be compared in a qualitative way with the degree of the color change. By utilizing this simple but effective process, the evolution of well-known ZnS passivation layer prepared from different chemical baths in quantum dot (QD)-sensitized solar cells could be tracked visually via checking the degree of color change of TiO2/ZnS electrodes after the induced specific cation exchange. When applied to representative CdS QD-sensitized solar cells, it was revealed clearly how the different degree and rate of ZnS deposition could affect the overall power conversion efficiency while finding an optimized passivation layer over TiO2/CdS electrode. Acetate anion-coupled Zn2+ source was observed to give a much faster deposition of ZnS passivation layer than nitrate anion one due to its higher pH-induced more favorable adsorption of Zn2+ on the surface of TiO2. As another useful application of the ZnS-based cation exchange, as-deposited ZnS was used as a template for preparing a more complex metal chalcogenide onto mesoporous TiO2 film. The ZnS-derived Sb2S3-sensitized electrode showed a promising initial result of over 1.0 % overall power conversion efficiency with a very thin ZrO2 passivation layer between TiO2 and Sb2S3.
关键词： passivation,Quantum dot-sensitizer,SILAR deposition,zinc sulfide,solar cell,cation exchange
更新于2025-09-23 15:21:01