Doped Clusters Research Articles

DFT Modeling of Isomerism of Doped Mg24L2 Clusters with Dopants L at the Surface and inside the Magnesium Cage

The isomers of Mg24L2 nanoclusters with dopants L from the firt three periods (L = Li–Zn) in the exo- and endohedral positions of the magnesium cage have been calculated by the density functional theory (DFT) method. The effect of dopants on the structure, stability, and position on the energy scale has been studied. For the systems with atoms L = H, Li, Be N, Na, Co, and Cu, the “open” positions of dopants at the surface are more favorable, unlike their analogs with L = Be and B, for which the “closed” positions in the inner cavity of the cluster are more favorable and their promotion to the surface requires a significant energy input. For clusters with O, Si, P, S, and early 3d metal atoms, the differences in the energies of the exo- and endohedral isomers do not exceed a few kcal/mol. The atoms of the second half of the 3d series are characterized by their association into diatomic dopants L2. The results are compared with the data of similar DFT calculations of isomers of Al42L2 aluminum clusters with the same dopants L = Li–Zn and are of interest for modeling the mechanisms of catalytic hydrogenation of magnesium and aluminum nanoclusters at the molecular level.

DFT Modeling of Isomerism of Doped Mg24L2 Clusters with Dopants L at the Surface and inside the Magnesium Cage

DFT Modeling of Isomerism of Doped Mg24L2 Clusters with Dopants L at the Surface and inside the Magnesium Cage

Solvent field regulated superhalogen in pure and doped gold cluster anions

Condensed-phase synthesis of atomically precise clusters has become a vital branch of cluster science, where solvents are indispensable in the synthesis process. Herein, by employing the density functional theory (DFT) calculations and molecular dynamics (MD) simulations, we demonstrated that polar solvents not only provide an important environment to stabilize clusters, but they can also dramatically alter the electronic property of cluster anions forming novel superhalogen anions. Such a regulation effect was first verified in small model gas-phase pure and doped gold cluster anions, which was further evidenced in a real experimentally synthesized Au18 nanocluster. Different solvation models reveal that the solvent field, which is a noninvasive methodology different from conventional electron-counting rules, can be considered as a novel external field to remarkably increase the electron-binding capability of cluster anions while maintaining their geometrical and electronic structures. Considering the indispensability and convenient availability of the solvents, present findings may boost the potential applications of superatoms in constructing super oxidizers in the condensed phase.

Insight into the Fe atom-FeS cluster synergistic catalysis mechanism for the oxygen evolution reaction in NiS2-based electrocatalysts.

The development of highly active oxygen evolution reaction (OER) catalysts with fast kinetics is crucial for the advancement of clean energy and fuel conversion to achieve a sustainable energy future. Recently, the synergistic effect of single-atom doping and multicomponent clusters has been demonstrated to significantly improve the catalytic activity of materials. However, such synergistic effects involving multi-electron and proton transfer processes are quite complex and many crucial mechanistic details need be well comprehended. We ingeniously propose a catalyst, (Fed-FeSc)@NiS2 (d stands for doping and c stands for clustering), with Fe and FeS acting synergistically on a NiS2 substrate. Specifically, fully dynamic monitoring of multiple active sites at the (Fed-FeSc)@NiS2 interface using metadynamics is innovatively performed. The results show that the rate determining step value at the overpotential of 1.23 V for the synergistic (Fed-FeSc)@NiS2 is 1.55 V, decreased by 6.67% and 35.29% compared to those of the independently acting single-atom doping and multi-clusters. The unique synergistic structure dramatically increases the d-band centre of the Fe site (-1.45 eV), endowing (Fed-FeSc)@NiS2 with more activity than conventional commercial Ir-C catalysts. This study provides insights into the synergistic effects of single-atom doping and multi-component clusters, leading to exploratory inspiration for the design of highly efficient OER catalysts.

Formation of pyramidal structures through mixing gold and platinum atoms: the AuxPty2+ clusters with x + y = 10.

The geometric and electronic structures of a small series of mixed gold and platinum AuxPty2+ clusters, with x + y = 10, were investigated using quantum chemical methods. A consistent tetrahedral pyramid structure emerges, displaying two patterns of structural growth by a notable critical point at y = 5. This affects the clusters' electron population, chemical bonding, and stability. For the Pt-doped Au clusters with y values from 2 to 5, the bonds enable Pt atoms to assemble into symmetric line, triangle, quadrangle, and tetragonal pyramidal Pty blocks, respectively. For the Au-doped Pt clusters, with larger values of y > 5, the structures are more relaxed and the d electrons of Pt atoms become delocalized over more centers, leading to lower symmetry structures. A certain aromaticity arising from delocalization of d electrons over the multi-center framework in the doped Pt clusters contributes to their stability, with Pt102+ at y = 10 exhibiting the highest stability. While the ground electronic state of the neutral platinum atom [Xe]. 4f145d96s1 leads to a triplet state (3D3), the total magnetic moments of AuxPty2+ are large increasing steadily from 0 to 10 μB and primarily located on Pt atoms, corresponding to the increase of the number of Pt atoms from 0 to 10 and significantly enhancing the magnetic moments. An admixture of both Au and Pt atoms thus emerges as an elegant way of keeping a small pyramidal structure but bringing in a high and controllable magnetic moment.

Doped metal clusters as bimetallic AuCo nanocatalysts: insights into structural dynamics and correlation with catalytic activity by in situ spectroscopy.

Co-doped Au25 nanoclusters with different numbers of doping atoms were synthesized and supported on CeO2. The catalytic properties were studied in the CO oxidation reaction. In all cases, an enhancement in catalytic activity was observed compared to the pure Au25 nanocluster catalyst. Interestingly, a different catalytic performance was obtained depending on the number of Co atoms within the cluster. This was related to the mobility of atoms within the cluster's structure under pretreatment and reaction conditions, resulting in active CoAu nanoalloy sites. The evolution of the doped Au clusters into nanoalloys with well-distributed Co atoms within the Au cluster structure was revealed by combined XAFS, DRIFTS, and XPS studies. Overall, these studies contribute to a better understanding of the dynamics of doped nanoclusters on supports upon pretreatment and reaction, which is key information for the future development and application of bimetallic nanocluster (nanoalloy) catalysts.

Structural Evolution and Electronic Properties of Selenium-Doped Boron Clusters SeBn0/- (n = 3-16).

A theoretical research of structural evolution, electronic properties, and photoelectron spectra of selenium-doped boron clusters SeBn0/- (n = 3-16) is performed using particle swarm optimization (CALYPSO) software in combination with density functional theory calculations. The lowest energy structures of SeBn0/- (n = 3-16) clusters tend to form quasi-planar or planar structures. Some selenium-doped boron clusters keep a skeleton of the corresponding pure boron clusters; however, the addition of a Se atom modified and improved some of the pure boron cluster structures. In particular, the Se atoms of SeB7-, SeB8-, SeB10-, and SeB12- are connected to the pure quasi-planar B7-, B8-, B10-, and B12- clusters, which leads to planar SeB7-, SeB8-, SeB10-, and SeB12-, respectively. Interestingly, the lowest energy structure of SeB9- is a three-dimensional mushroom-shaped structure, and the SeB9- cluster displays the largest HOMO-LUMO gap of 5.08 eV, which shows the superior chemical stability. Adaptive natural density partitioning (AdNDP) bonding analysis reveals that SeB8 is doubly aromatic, with 6 delocalized π electrons and 6 delocalized σ electrons, whereas SeB9- is doubly antiaromatic, with 4 delocalized π electrons and 12 delocalized σ electrons. Similarly, quasi-planar SeB12 is doubly aromatic, with 6 delocalized π electrons and 14 delocalized σ electrons. The electron localization function (ELF) analysis shows that SeBn0/- (n = 3-16) clusters have different local electron delocalization and whole electron delocalization effects. The simulated photoelectron spectra of SeBn- (n = 3-16) have different characteristic bands that can identify and confirm SeBn- (n = 3-16) combined with future experimental photoelectron spectra. Our research enriches the geometrical structures of small doped boron clusters and can offer insight for boron-based nanomaterials.

Insights on the enhanced hydrogen sulfide adsorption on X (X = Cr, Ni, Al, C, Si, O, S) doped boron nitride nanotubes

This study investigates the enhanced hydrogen sulfide (H2S) gas adsorption on X (X = Cr, Ni, Al, C, Si, O, and S) doped boron nitride nanotubes (BNNT) through first-principle density functional theory calculations. The study also examined the electrostatic potential maps, HOMO-LUMO distributions, density of states plots, atomic charges, and reactivity descriptors of doped BNNT clusters before and after adsorption. The H2S orientation was different for each optimized doped BNNT-H2S cluster. The theoretical infrared spectra indicated a red shift in the SH symmetric stretching frequency of H2S gas molecule upon adsorption on pristine and doped BNNT. The examination of the atomic charges showed that during the interaction, the charge was transferred from the doped BNNT to the H2S gas molecule. The analysis revealed that Al/BNNT and S/BNNT exhibited better interactions and, therefore, better adsorption ability towards H2S gas than pristine and other doped BNNT. However, considering the recovery time aspect, C/BNNT, O/BNNT, and Si/BNNT were better adsorbent for H2S.

Improved Efficiency and Stability of Perovskite Solar Cells Using the Multifunctional Additive Au Clusters

The great potential of perovskite solar cells (PSCs) remains to be further exploited via the improvement of their incomplete photon absorption and the reduction of abundant defects in perovskite. Here, we added Au clusters with 3-methylbenzenethiol (m-MBT) as ligands in perovskite to investigate the effect of surface plasmons on the light absorption of the perovskite layer and the passivation of m-MBT on the defects for perovskite. The results show that the addition of Au clusters not only effectively enhances the light absorption ability of perovskite but also effectively passivates the defects and suppresses the charge recombination. Meanwhile, we discuss the effect of doped Au clusters on the performance of PSCs. The power conversion efficiency of Au cluster-optimized PSCs was greatly improved to 20.6% from 18.8% for the control PSCs. In addition, due to the reduction of defects in perovskite, the stability of the improved PSCs is also greatly improved.

Gold-Hydrogen Analogy in Small-Sized Hydrogen-Doped Gold Clusters Revisited.

The analogy between gold and hydrogen is a subject of long-standing debate. In the present work, we examine the validity of the gold-hydrogen analogy in a series of small-sized H-doped gold clusters, Aun-1 H with n varying between 2 and 10 and also investigate its dependence on the cluster size. Keeping in mind the importance of the role of structures, we make use of the genetic algorithm coupled with a density functional theory based method to exhaustively search and identify the energetically low-lying structures of each of the H-doped gold clusters. These lower energy structures of H-doped and pristine gold clusters are then employed to carry out the calculations of their electronic properties, stability analysis as well as their reactivity towards the adsorption and activation of CO and O2 molecules. Our study shows that in line with the gold-hydrogen analogy, both electronic properties and the adsorption/activation characteristics of H-doped gold clusters remain very similar to those of pristine gold clusters.

Inorganic doped libethenite nanoparticle clusters show high catalytic activity in hydrogen evolution reaction

A noble metal-free Na Al Si doped libethenite nanoparticle clusters were obtained by applying the method of hydrothermal synthesis. The Linear Sweep Voltammetry (LSV) curve of this nanoparticle cluster electrode shows that there is no noble metal in the hydrogen evolution reaction (HER), and it still exhibits good catalytic activity. The catalytic activity of the libethenite nanoparticle cluster is further enhanced after reduction by the amperometric i-t curve method (A i-t C). The electrochemical performance and catalytic mechanism were investigated by the cyclic voltammetry (CV) method. The characterization analysis by XRD, SEM, TEM, EDS, and XPS found that the catalyst was isomorphous with the natural mineral libethenite, but different from the minerals with Cu and P as the main components in nature when the crystal synthesized under hydrothermal conditions was doped. The heterogenous libethenite nanoparticle cluster framework is replaced by more additional Na, Al, and Si elements. Cu and P elements in the libethenite nanoparticle cluster structure are connected through the mineral framework and uniformly distributed in the crystal structure. This structure increases the electrochemical activity of its HER. Due to the interaction of Cu and P, the catalyst exhibits good catalytic performance for HER under acidic conditions. The reduction by the electrochemical i-t curve reduces the consumption of Cu and enhances the stability of the mineral framework.

First Principle Calculation: Effect of Doped Gold Clusters with Platinum Atom on Chemical Catalysis

In this paper, we present a systematic computational study based on the density function theory (DFT), Which aims to shed light on the potential effects of doped gold Au clusters with a platinum Pt atom,and finding the new structural and electronic properties that will be enjoyed by gold doped with platinum PtAun (n = 1-9) clusters, So that the most stable clusters are selected from the rest of the isomers for each cluster size. We doped Aun clusters with Pt atom, we obtained very interesting results, Stable and most stable structures reveal three-dimensional structures starting from (n=6), Also, the results of the fragmentation energy and the second difference in binding energy of these clusters in relation to their size have been studied in depth. The electronic properties, such as the Homo-Lumo gap energy, Vertical ionization potential (VIP) and adiabatic ionization potential (AIP) as a function of cluster size are also studied and discussed. All properties calculated by the generalized gradient approximation (GGA) were compared with the results of the local density approximation (LDA). Whereas, the results showed that the Aun clusters doped with Pt atom changed significantly.

Geometric, electronic and spectral properties of germanium and Eu-doped germanium clusters

This study explored the geometric, electronic, and spectral properties of germanium and Eu-doped germanium clusters and compared their simulated PES spectra. The stability of Gen and EuGen nanoclusters was examined with density functional theory using FHI-aims as a software package. Symmetry-adapted cluster-configuration interaction general-R (SAC-CI-General-R) method and the SDD basis set were adopted to determine ionization energies and calculate their intensities. Natural bond orbital (NBO) calculations were performed to determine the effective molecular orbitals in the ionization and study the electron density on the nanoclusters. The shape of molecular orbitals (MO) involved in the ionization process for each structure was displayed and interpreted. The analyses of binding energies showed that increasing the size of nanoclusters leads to more stability for nanoclusters. Ionization energy and the photoelectron spectrum of these clusters indicated that Eu as an impurity reduces ionization energy and shifts the ionization processes towards infrared wavelengths. Interestingly, pure and doped clusters followed a similar pattern in terms of an increase/decrease in the first ionization energy compared to n-1 and n + 1 clusters.

Two-layer molecular rotors: A zinc dimer rotating over planar hypercoordinate motifs.

Multi-layer molecular rotors represent a class of unique combination of topology and bonding, featuring a barrier-free rotation of one layer with respect to other layers. This emerging fluxional behavior has been found in a few doped boron clusters. Herein, we strongly enrich this intriguing family followed by an effective design strategy, summarized as essential factors: i) considerable electrostatic interactions originated from a strong charge transfer between layers; ii) the absence of strong covalent bonds between layers; and iii) fully delocalized σ/π electrons from at least one layer. We found that planar hypercoordinate motifs consisting of monocyclic boron rings and metals with σ + π dual aromaticity can be regarded as one promising layer, which can support the suspended X2 (X=Zn, Cd, Hg) dimers. By detailed investigations of thermodynamic and kinetic stabilities of 60 species, eventually, MB7 X2 - and MB8 X2 (X=Zn, Cd; M=Be, Ru, Os; Be works only for Zn-based cases) clusters were verified to be the global-minimum two-layer molecular rotors. Especially, their electronic structure analyses vividly confirm the practicability of the electronic structure requirements mentioned above for designing multi-layer molecular rotors.

Computational Exploration on the Structural and Optical Properties of Gold-Doped Alkaline-Earth Magnesium AuMgn (n = 2-12) Nanoclusters: DFT Study.

Using CALYPSO crystal search software, the structural growth mechanism, relative stability, charge transfer, chemical bonding and optical properties of AuMgn (n = 2–12) nanoclusters were extensively investigated based on DFT. The shape development uncovers two interesting properties of AuMgn nanoclusters contrasted with other doped Mg-based clusters, in particular, the planar design of AuMg3 and the highly symmetrical cage-like of AuMg9. The relative stability study shows that AuMg10 has the robust local stability, followed by AuMg9. In all nanoclusters, the charge is transferred from the Mg atoms to the Au atoms. Chemical bonding properties were confirmed by ELF analysis that Mg-Mg formed covalent bonds in nanoclusters larger than AuMg3. Static polarizability and hyperpolarizability calculations strongly suggest that AuMg9 nanocluster possesses interesting nonlinear optical properties. Boltzmann distribution weighted average IR and Raman spectroscopy studies at room temperature verify that these nanoclusters are identifiable by spectroscopic experiments. Finally, the average bond distance and average nearest neighbor distance were fully investigated.

Structures, stabilities and infrared spectra of AgnCr clusters (n=2-12) by density functional theory calculation

Nanoclusters have been emerging as potential building blocks for advanced nanostructured materials with desired catalytic, magnetic, and electronic properties. However, determining the structure of doped atomic clusters encounters many difficulties. A powerful approach to assign the ground state geometries of atomic clusters has been the comparison the recorded vibrational infrared spectra with the corresponding computed ones. In this work, we theoretically investigate the vibrational infrared spectra of the ground-state structures of AgnCr (n=2-12) clusters using density functional theory (DFT) calculations. The results of the investigation are useful for in-depth studies on size growth as well as experiments for determining the cluster structures in the future.

Structures, and electronic and spectral properties of single-atom transition metal-doped boron clusters MB24 - (M = Sc, Ti, V, Cr, Mn, Fe, Co, and Ni).

A theoretical study of geometrical structures, electronic properties, and spectral properties of single-atom transition metal-doped boron clusters MB24− (M = Sc, Ti, V, Cr, Mn, Fe, Co, and Ni) is performed using the CALYPSO approach for the global minimum search, followed by density functional theory calculations. The global minima obtained for the MB24− (M = Sc, Ti, V, and Cr) clusters correspond to cage structures, and the MB24− (M = Mn, Fe, and Co) clusters have similar distorted four-ring tubes with six boron atoms each. Interestingly, the global minima obtained for the NiB24− cluster tend to a quasi-planar structure. Charge population analyses and valence electron density analyses reveal that almost one electron on the transition-metal atoms transfers to the boron atoms. The electron localization function (ELF) of MB24− (M = Sc, Ti, V, Cr, Mn, Fe, Co, and Ni) indicates that the local delocalization of MB24− (M = Sc, Ti, V, Cr, and Ni) is weaker than that of MB24− (M = Mn, Fe, and Co), and there is no obvious covalent bond between doped metal and B atoms. The spin density and spin population analyses reveal that open-shell MB24− (M = Ti, Cr, Fe, and Ni) has different spin characteristics which are expected to lead to interesting magnetic properties and potential applications in molecular devices. The polarizability of MB24− (M = Sc, Ti, V, Cr, Mn, Fe, Co, and Ni) shows that MB24− (M = Mn, Fe, and Co) has larger first hyperpolarizability, indicating that MB24− (M = Mn, Fe, and Co) has a strong nonlinear optical response. Hence, MB24− (M = Mn, Fe, and Co) might be considered as a promising nonlinear optical boron-based nanomaterial. The calculated spectra indicate that MB24− (M = Sc, Ti, V, Cr, Mn, Fe, Co, and Ni) has different and meaningful characteristic peaks that can be compared with future experimental values and provide a theoretical basis for the identification and confirmation of these single-atom transition metal-doped boron clusters. Our work enriches the database of geometrical structures of doped boron clusters and can provide an insight into new doped boron clusters.

Exploring the structure and electronic properties of germanium doped boron clusters using density functional theory based global optimization method

Density functional theory calculations to investigate the effect of single and double germanium atom doping on the geometric structure and electronic properties of boron clusters with 10 to 20 atoms.

Transition-metal doped titanium-oxo clusters with diverse structures and tunable photochemical properties

Transition metal doping effectively tuned the photochemical properties of titanium-oxo clusters {Ti2Mn4}, {Ti8Co5} and {Ti12Cd5}.

Amorphous Ru nanoclusters onto Co-doped 1D carbon nanocages enables efficient hydrogen evolution catalysis

The development of high-performance electrocatalysts for hydrogen evolution reaction (HER) is of great significance for green, sustainable, and renewable energy conversion. Herein, we report the synthesis of amorphous Ru clusters on Co-doped defect -rich hollow carbon nanocage (a-Ru@Co-DHC) as an efficient electrocatalyst for HER in the basic media. Due to the advantages such as high surface area, rich edge defect, atomic Co doping and amorphous Ru clusters, the as-made a-Ru@Co-DHC displays an efficient HER performance with a near-zero onset overpotential, a low Tafel slope (62 mV dec −1 ), a low overpotential of 40 mV at 10 mA cm −2 and high stability, outperforming the commercial Ru nanocrystal/C, commercial Pt/C, and other reported Ru-based catalysts. This work provides a new insight into designing new metal doped carbon nanocages catalysts supported by amorphous nanoclusters for achieving the enhanced electrocatalysis. A novel kind of amorphous Ru clusters@Co-doped defect-rich hollow carbon nanocage (a-Ru@Co-DHC) catalyst has been developed for efficient electrocatalysis of hydrogen evolution reaction in basic media due to synergistic effect of edge defect, atomic Co doping and dispersed amorphous Ru clusters.