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Turning Au Nanoclusters Catalytically Active for Visible-Light-Driven CO2 Reduction through Bridging Ligands
摘要： Developing visible-light photocatalytic materials is an ultimate goal for solar-driven CO2 conversion. Au nanoclusters may potentially serve as the components for harvesting visible light, but can hardly perform the solar-driven CO2 reduction due to the lack of catalytic sites. Herein, we report an effective strategy for turning Au nanoclusters catalytically active for visible-light CO2 reduction, in which metal cations (Fe2+, Co2+, Ni2+ and Cu2+) are grafted to the Au NCs using L-cysteine as a bridging ligand. The metal-S bonding bridge facilitates the electron transfer from Au NCs to metal cations so that the grafted metal cations can receive photo-induced electrons and work as catalytic sites for CO2 reduction. The varied d-band centers and binding energies with CO2 for different metal cations allow tuning electron transfer efficiency and CO2 activation energy. Furthermore, the photostability of Au NCs-based catalyst can be significantly enhanced through the encapsulation with metal-organic frameworks. This work opens a new door for the photocatalyst design based on metal clusters, and sheds light on the surface engineering of metal clusters toward specific applications.
关键词： gold cluster,CO2 reduction,ligand,catalytic sites,Photocatalysis
更新于2025-09-23 15:21:21
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Improved Models for Metallic Nanoparticle Cores From Atomic Pair Distribution Function (PDF) Analysis
摘要： X-ray atomic pair distribution functions (PDFs) were collected from a range of canonical metallic nanomaterials, both elemental and alloyed, prepared using different synthesis methods and exhibiting drastically different morphological properties. Widely applied shape-tuned attenuated crystal (AC) fcc models proved inadequate, yielding structured, coherent, and correlated fit residuals. However, equally simple discrete cluster models could account for the largest amplitude features in these difference signals. A hypothesis testing based approach to nanoparticle structure modelling systematically ruled out effects from crystallite size, composition, shape, and surface faceting as primary factors contributing to the AC misfit. On the other hand, decahedrally twinned cluster cores were found to be the origin of the AC structure misfits for a majority of the nanomaterials reported here. It is further motivated that the PDF can readily differentiate between the arrangement of domains in these multiply-twinned motifs. Most of the nanomaterials surveyed also fall within the sub-5 nm size regime where traditional electron microscopy cannot easily detect and quantify domain structures, with sampling representative of the average nanocrystal synthesized. The results demonstrate that PDF analysis is a powerful method for understanding internal atomic interfaces in small noble metallic nanomaterials. Such core cluster models, easily built algorithmically, should serve as starting structures for more advanced models able to capture atomic positional disorder, ligand induced or otherwise, near nanocrystal surfaces.
关键词： decahedrally twinned cluster cores,PDF analysis,metallic nanomaterials,nanocrystal surfaces,X-ray atomic pair distribution functions
更新于2025-09-23 15:21:21
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Numerical stability of time-dependent coupled-cluster methods for many-electron dynamics in intense laser pulses
摘要： We investigate the numerical stability of time-dependent coupled-cluster theory for many-electron dynamics in intense laser pulses, comparing two coupled-cluster formulations with full configuration interaction theory. Our numerical experiments show that orbital-adaptive time-dependent coupled-cluster doubles (OATDCCD) theory offers significantly improved stability compared with the conventional Hartree-Fock-based time-dependent coupled-cluster singles-and-doubles (TDCCSD) formulation. The improved stability stems from greatly reduced oscillations in the doubles amplitudes, which, in turn, can be traced to the dynamic biorthonormal reference determinants of OATDCCD theory. As long as these are good approximations to the Brueckner determinant, OATDCCD theory is numerically stable. We propose the reference weight as a diagnostic quantity to identify situations where the TDCCSD and OATDCCD theories become unstable.
关键词： time-dependent coupled-cluster theory,OATDCCD,Brueckner determinant,TDCCSD,intense laser pulses,numerical stability,many-electron dynamics
更新于2025-09-23 15:21:01
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Cd12O12 cage cluster-assembled nanowires and band gap regulation: A first-principles investigation
摘要： Based on the first-principle calculation, the stability and electronic properties of Cd12O12 cluster-assembled nanowires and Na-doped Cd12O12 nanowire are studied. The results show that both Cd12O12 nanowire and Na-doped Cd12O12 nanowire are thermodynamically stable (at least at room temperature). The most stable Cd12O12 nanowire exhibits semiconducting properties with a direct energy gap. After doping Na atoms into the nanowire, the electronic properties of the Cd12O12-based nanowire present dramatic changes, and the system transforms from semiconducting to metallic. It can provide a theoretical guidance for the potential application of Cd12O12-based semiconductor devices.
关键词： Assembly,Band gap regulation,Na doped,Cd12O12 cage cluster,Cd12O12 nanowire
更新于2025-09-23 15:21:01
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Study of the parameter dependence of laser-accelerated protons from a hydrogen cluster source
摘要： We present a study on laser-driven proton acceleration from a hydrogen cluster target. Aiming for the optimisation of the proton source, we performed a detailed parametric scan of the interaction conditions by varying different laser and the target parameters. While the underlying process of a Coulomb-explosion delivers moderate energies, in the range of 100 s of keV, the use of hydrogen as target material comes with the bene?t of a debris-free, single-species proton acceleration scheme, enabling high repetition-rate experiments, which are very robust against shot-to-shot ?uctuations.
关键词： hydrogen cluster,coulomb-explosion,cryogenic target,laser-driven ion acceleration
更新于2025-09-23 15:21:01
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Influence of Matrix Nature on the Structural Characteristics of In2O3–CeO2 and SnO2–CeO2 Composites Fabricated by the Impregnation Method
摘要： The structural characteristics, valence states, and distribution of cerium ions between the components in In2O3–CeO2 and SnO2–CeO2 nanocomposites fabricated using the impregnation method were studied. X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDX) were used to show that, during impregnation, cerium ions are not included into In2O3 crystals and are disposed only on their surface in the form of nano-sized crystallites or amorphous clusters. On the other side, under the contact of CeO2 clusters with a surface of SnO2 matrix crystals, cerium ions penetrate into the surface layer of these crystals. In contrast to an In2O3–CeO2 system, where the addition of CeO2 does not affect the conduction activation energy, where cerium oxide is added to SnO2, the observed increase in the resistance of a SnO2–CeO2 composite is accompanied by a sufficient increase in activation energy. These data and the XPS spectra confirm the modification of the surface layers of conductive SnO2 crystals as, a result of the penetration of cerium ions into these layers.
关键词： cluster,conductometric sensor,metal oxide nano-sized composites,semiconductor,impregnation method
更新于2025-09-23 15:21:01
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Third-Order Unitary Coupled Cluster (UCC3) for Excited Electronic States: Efficient Implementation and Benchmarking
摘要： The efficient implementation of the third-order unitary coupled-cluster scheme (UCC3) for the calculation of excited electronic states is reported. The UCC3 scheme and its second-order UCC2 variant have been benchmarked and compared to Jacquemin’s recently introduced as well as Thiel’s well-established benchmark sets for excitation energies and oscillator strengths. For the latter, the calculation of 134 excited singlet and 71 excited triplet states of 28 small to medium-sized organic molecules has revealed that UCC2 exhibits a mean error and standard deviation of 0.36 ± 0.41 eV for singlet states and 0.22 ± 0.21 eV for triplet states, whereas UCC3 revealed an accuracy of 0.06 ± 0.27 eV for singlet and ?0.22 ± 0.15 eV for triplet states. Additionally, the oscillator strengths obtained with effective transition moments correct through second order in perturbation theory are in very good agreement with literature data.
关键词： perturbation theory,unitary coupled-cluster,oscillator strengths,excited electronic states,benchmarking
更新于2025-09-23 15:21:01
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Bidirectional Quantum Teleportation of Two-Qubit State Via Four-Qubit Cluster State
摘要： In this paper, a novel scheme of bidirectional quantum teleportation is proposed, where two-qubit states are transferred into single qubit superposition by Alice and Bob respectively using controlled-NOT operation, meanwhile the four-qubit cluster states are utilized as quantum channel. Our main novelty, which is the significant difference from other schemes of bidirectional (controlled) quantum teleportation, is: as the receivers, the both legitimate users can reconstruct the target two-qubit states through the corresponding unitary operation and controlled-NOT transmission to realize the more efficient teleportation.
关键词： Controlled-NOT operation,Bidirectional quantum teleportation,Four-qubit cluster state
更新于2025-09-23 15:21:01
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Clustered atom-replaced structure in single-crystal-like metal oxide
摘要： By means of metal organic deposition using tri?uoroacetates (TFA-MOD), we replaced and localized two or more atoms in a single-crystalline structure having almost perfect orientation. Thus, we created a new functional structure, namely, clustered atom-replaced structure (CARS), having single-crystal-like metal oxide. We replaced metals in the oxide with Sm and Lu and localized them. Energy dispersive x-ray spectroscopy results, where the Sm signal increases with the Lu signal in the single-crystalline structure, con?rm evidence of CARS. We also form other CARS with three additional metals, including Pr. The valence number of Pr might change from 3+ to approximately 4+, thereby reducing the Pr–Ba distance. We directly observed the structure by a high-angle annular dark-?eld image, which provided further evidence of CARS. The key to establishing CARS is an equilibrium chemical reaction and a combination of additional larger and smaller unit cells to matrix cells. We made a new functional metal oxide with CARS and expect to realize CARS in other metal oxide structures in the future by using the above-mentioned process.
关键词： superconductor,YBCO,quasi-liquid network model,clustered atom-replaced structure,cluster,TFA-MOD
更新于2025-09-23 15:21:01
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Study on Formation Process and Models of Linear Fe Cluster Structure on a Si(111)-7 × 7-CH3OH Surface
摘要： STM results showed that Fe atoms were deposited on a Si(111)-7 × 7 reconstructed surface, which was saturated with CH3OH molecules. Fe atomic linear structure was composed of stable clusters and in-situ observed by the scanning tunneling microscopy (STM). The aim to improve its application of magnetic memory material, both formation process and models, has been explored in this paper. By combining surface images and mass spectrometer data, an intermediate layer model was established. In terms of thermal stability, the most favorable adsorption sites of CH3OH were further explored. After that, Fe atoms were deposited on the Si(111)-7 × 7-CH3OH surface, forming a linear cluster structure. On the one hand, a new Fe cluster model was put forward in this paper, which was established with height measurement and 3D surface display technology. This model is also affected by the evaporation temperature, which can be consistent with the atomic stacking pattern of face centered cubic structures. On the other hand, the slight height change suggested the stability of linear structures. Even in the condition of thin air introduction, Fe cluster showed a good performance, which suggested the possibility of magnetic memory application in the future. These investigations are believed to have, to a certain extent, increased the probability of forming Fe linear clusters on the surface of silicon substrate, especially according to the models and surface technology we adjusted.
关键词： cluster,CH3OH,STM,linear structure,evaporation
更新于2025-09-23 15:21:01