Au Atoms Research Articles

Correlating Heteroatoms Doping, Electronic Structures, and Photocatalytic Activities of Single‐Atom‐Doped Ag25(SR)18 Nanoclusters

Atomic‐level manipulation of catalysts is important for both fundamental studies and practical applications. Here, the central metal atom in an atomically precise Ag25 nanocluster (NC) is replaced with a single Pd, Pt, and Au atom, respectively, and employed as a model system to study the structure–property–activity relationship at the atomic level. While the geometric structures are well‐preserved after doping, the electronic structures of Ag25 NCs are significantly altered. The combination of Ag25 and TiO2 enhances the charge separation at the interface, exhibiting a 10 times higher hydrogen production rate in photocatalytic hydrogen evolution reaction compared to bare TiO2. Further results show that heteroatoms doping has a negative impact on performance, particularly in the cases of Pd and Au doping. Ultraviolet photoelectron spectroscopy measurements and density functional theory calculations suggest that the lower activities are due to an energy mismatch between the levels of doped NCs and TiO2. These findings not only reveal the impact of heteroatoms doping on the electronic properties and photocatalytic activities of NCs, but can also guide the design of heterometallic NCs for photocatalytic applications.

Au core@AuPtRh alloy shell nanowires for ethanol oxidation

The highly active, selective and stable anode electrocatalysts for the ethanol oxidation reaction (EOR) are extremely desirable for the application of direct ethanol fuel cells (DEFCs). Herein, one-dimensional Au core@AuPt0·20Rh0.08 alloy shell nanowires (Au@AuPt0·20Rh0.08 CS-NWs) with long aspect ratio and cross-linked network architecture are synthesized. For the EOR, Au@AuPt0·20Rh0.08 CS-NWs display higher peak current density, better resistance to CO poisoning and more lasting stability compared with Au@AuPt0.28 CS-NWs and commercial Pt black electrocatalyst, which can be attributed to the trimetallic synergistic effect between the Au, Pt and Rh atoms. Specifically, the Rh can promote the C–C bonds and adsorb OHads while Au can change the electronic structure of Pt, endowing Pt with a high anti-poisoning ability to COads and promoting the complete oxidation of various C1 intermediate to CO2. This work provides an effective strategy for the rational construction of high-performance Pt-based EOR electrocatalysts by optimizing composition, morphology and architecture.

Angle-differential cross sections for Rayleigh scattering of highly linearly polarized hard x rays on Au atoms

We perform a study on Rayleigh scattering of highly linearly polarized hard x rays on a thin Au foil target. In the study the angular distribution of the scattered radiation is analyzed in a relativistic regime both within and out of the plane of polarization of the incident beam. Within this experiment we scatter a synchrotron beam with a photon energy of 175 keV on a high-$Z$ target foil, namely, gold. Our findings correlate well with state-of-the-art calculations of the scattering process performed in the framework of quantum electrodynamics and may have considerable impact on future experiments regarding a polarization-resolved analysis of Delbr\"uck scattering. Furthermore, we show that the angular distribution of Rayleigh scattering can be used for a highly sensitive determination of the degree and orientation of the linear polarization of the incident hard-x-ray beam, if we rely on the theoretical framework.

Single atom alloy clusters Agn-1X- (X = Cu, Au; n = 7-20) reacting with O2: Symmetry-adapted orbital model.

Single atom alloy AgCu catalysts have attracted great attention, since doping the single Cu atom introduces narrow free-atom-like Cu 3d states in the electronic structure. These peculiar electronic states can reduce the activation energies in some reactions and offer valuable guidelines for improving catalytic performance. However, the geometric tuning effect of single Cu atoms in Ag catalysts and the structure-activity relationship of AgCu catalysts remain unclear. Here, we prepared well-resolved pristine Agn - as well as single atom alloy Agn-1Cu- and Agn-1Au- (n = 7-20) clusters and investigated their reactivity with O2. We found that replacing an Ag atom in Agn - (n = 15-18) with a Cu atom significantly increases the reactivity with O2, while replacement of an Ag with an Au atom has negligible effects. The adsorption of O2 on Agn - or Agn-1Cu- clusters follows the single electron transfer mechanism, in which the cluster activity is dependent on two descriptors, the energy level of α-HOMO (strong correlation) and the α-HOMO-LUMO gap (weak correlation). Our calculation demonstrated that the cluster arrangements caused by single Cu atom alloying would affect the above activity descriptors and, therefore, regulates clusters' chemical activity. In addition, the observed reactivity of clusters in the representative sizes with n = 17-19 can also be interpreted using the symmetry-adapted orbital model. Our work provides meaningful information to understand the chemical activities of related single-atom-alloy catalysts.

Element-ratio dependence of the 5d-states of Au and Pt in solid-solution-type Au-Pt alloy nanoparticles studied by X-ray absorption spectroscopy and density functional theory.

Solid-solution-type Au-Pt alloy nanoparticles (NPs) were prepared from the nanoclusters of each metal using the polymer-conjugated fusion growth method. The elemental mapping analysis showed that the mixing state of the elements in the NPs drastically changed in the narrow reaction-temperature range from 100 °C to 180 °C. For their various mixing states, the 5d-states of Au and Pt atoms in the alloy NPs were investigated on the basis of the white line intensities of X-ray absorption near edge structure (XANES). Then, the 5d-states of Au and Pt atoms in a model crystalline ordered alloy structures were investigated on the basis of the theoretically calculated XANES spectra using density functional theory (DFT) in the whole composition range. The DFT calculation showed that the changes in the absorption spectra near the Pt and Au edges are caused by the change in the occupation of the Pt 5d-states and the orbital hybridisation of the Au 5d-states with the 5d-states of neighbouring Pt atoms around an Au atom, respectively.

Light- and thermal-driven gold-catalyzed reaction of o-alkynylphenols with aryldiazonium salts: Computational insights into mechanistic similarities and differences

It was experimentally found that the gold-catalyzed reaction between o-alkynylphenols and aryldiazonium salts can lead to different products under thermo- and photocatalytic conditions; however, the mechanism is elusive. Herein we have employed both MS-CASPT2 and DFT approaches to study the catalytic mechanisms of the corresponding light- and thermal-driven reactions. The results show that both the thermo- and photo-catalytic reactions share some same elementary steps from the Au(I) catalyst and o-alkynylphenol, both of which generate a vinyl Au(I) intermediate with the aid of HCO3−. In these steps, the formation of a structurally distorted complex of the Au(I) catalyst and o-alkynylphenol has a free energy barrier of 14.8 kcal/mol in that the C≡C triple bond of o-alkynylphenol is seriously activated. Importantly, the thermo- and photo- catalytic reactions start to diverge from the complex formed between the generated vinyl Au(I) intermediate and the aryldiazonium salt. Under the dark condition, the reaction proceeds to generate the final thermal product after overcoming a free energy barrier of 15.7 kcal/mol, in which the terminal N atom of the aryldiazonium salt is bonded directly to the C atom of the Au(I) species. In the photoirradiation condition, the complex is first excited to its electronically excited singlet state, which then decays to the T1 state with an efficient intersystem crossing process of 9.8x109 s−1. In the T1 state, the denitrogen process completes easily after overcoming a free energy barrier of 7.8 kcal/mol resulting into an aryl radical interacting with the Au atom of the vinyl Au(I) species, which is followed by another intersystem crossing process from T1 to S0. In the S0 state, the final photocatalytic product is formed. The present work provides important mechanistic details on understanding both thermo- and photo-catalytic reactions of Au(I) catalysts and aryldiazonium salts, and most importantly, it is found that nonradiative transitions play an essential role in regulating photocatalytic reactions.

Measurement of distribution of charge adsorbed on Au<i><sub>x</sub></i>/Si(111)-7×7 surface on an atomic scale in ultra-high vacuum

The physicochemical properties of Au atoms adsorbed on the surface on an atomic scale play a very important role in preparing nanodevices and surface catalysis. In this paper, we use frequency modulated Kelvin probe force microscopy (FM-KPFM)to study the multi-bit adsorbed charge distribution of Au on the surface of Si(111)-(7×7) at room temperature. Firstly, the surface topography and local contact potential difference (LCPD) of Au at different adsorption sites in Si(111)-(7×7) are successfully obtained by using home-made ultra-high vacuum Kelvin probe force microscopy. Secondly, we analyze the atomic characteristics of specific atomic positions of Au/Si(111)-(7×7) by force spectroscopy and potential difference, and realize the atomic identification . The adsorption characteristics of Au/Si(111)-(7×7) surface charge transfer and Au are explained by combining differential charge density calculations. The results show that Au atom adsorption mainly is in the form of single atom and cluster . Specifically, the Au cluster is adsorbed at the three central positions of Si(111)-(7×7) in a hexagonal structure of six atoms. Individual Au atoms are adsorbed to the positions of central adatoms of Si(111)-(7×7). At the same time, through the measurement of potential difference, it is known that a single Au atom and Au cluster lose electrons, presenting a positive electrical characteristic. The results of surface differential charge density show that Au undergoes charge transfer during adsorption, losing part of the charge, which locally reduces the work function at the position of the adsorbed atom. In the range of distances where short-range forces, local contact potential energy differences and differential charge densities change, the theoretical results and experimental results are in reasonable agreement.

Gold(III) derivatives as the noncovalent interaction donors: theoretical study of the π-hole regium bonds.

Except for the well-known σ-hole regium bonds formed by metal nanoparticles and M(I) (M = Cu, Ag, and Au) derivatives, the existence of π-hole regions located above and below the Au atom in gold(III) derivatives suggests that gold(III) also functions as an efficient electrophilic site. In this study, a comprehensive analysis was conducted on the electrophilicity of trichloro-(p-toluonitrilo-N)-gold(III) derivatives AuL3(NCC6H4X) (L = Cl, Br, CN; X = NH2, CH3, CF3, NC, and CN) and the nature of π-hole regium bonds in the AuL3(NCC6H4X)⋯LB (LB = NH3, N(NH3)3, CH2O, C2H2, C2H4, C6H6) and (AuCl3(NCC6H4Y))n (Y = Cl, CN, NC, NO2; n = 2, 3)) complexes. The characteristics of the π-hole regium bonds were studied with respect to the influence of ligands and substituents, the strength of intermolecular interactions between Au(III) derivatives and Lewis bases, and those in the polymers. In the case of the AuL3(NCC6H4X)⋯NH3 complexes, the strength of the regium bonds increases gradually in the order of L = Cl < Br < CN and X = NH2 < CH3 < CF3 ≈ NC < CN. The ligands (L) attached to the Au atom exert a significant effect on the strength of the π-hole regium bonds in comparison to the substituents (X) on the benzene ring. The regium bonds are primarily dominated by electrostatic interaction, accompanied by moderate contribution from polarization. Linear relationships were identified between the electrostatic energies and the local most positive potentials over the Au atom, as well as between the polarization energies and the amount of charge transfer. Most of the π-hole regium bonds in the AuL3(NCC6H4X)⋯LB complexes exhibit the characters of closed shell noncovalent interactions. In the polymers (AuCl3(NCC6H4Y))n, weak face-to-face π-π stacking interactions are also present, in addition to regium bonds. The trimers displayed a slightly negative cooperativity in comparison to the dimers.

Overall structure of Au12Ag60(S-c-C6H11)31Br9(Dppp)6: achieving a stronger assembly of icosahedral M13 units.

Precise atomically assembled nanoclusters provide a great platform to elucidate the evolution of the assembly of building blocks. Herein, a large icosahedral (M13)-based silver-gold alloy nanocluster [Au12Ag60(S-c-C6H11)31Br9(Dppp)6]Br2 (dppp = 1,3-bis(diphenylphosphino)propane) is reported. Structurally, Au12Ag60 consists of an Au12Ag40 kernel, which is viewed as the interpenetration of ten twisted complete icosahedrons (M13) and two missing icosahedrons (M12), and this is surrounded by a complex metal-organic shell. Benefiting from the extra doping of eight to twelve Au atoms, the octameric assembly was increased to a twelve-mer assembly. The time-dependent density functional theory (TDDFT) method with a Tamm-Dancoff approximation (TDA) was performed to investigate the difference in the optical properties of Au12Ag60 and Au8Ag57. The results indicate that the difference in the amount of Au atoms results in different optical properties. Furthermore, transient absorption spectroscopy (TA) was also performed, revealing that a twelve-mer assembly greatly enhances the excited-state lifetime. The [Au12Ag60(S-c-C6H11)31Br9(Dppp)6]Br2 alloy nanocluster has provided a breakthrough in the number of icosahedral M13 assemblies, i.e., achieving a twelve-mer assembly, helping to elucidate the fusion growth of M13-based assembled nanoclusters as well as their geometric/electronic structure correlations, which will promote further research on the assembly of M13 nano-building blocks, especially on their optical properties.

Influence of ligands on the optical properties of rod-shaped Au25 nanoclusters.

In this study, we successfully synthesized rod-shaped [Au25(PPh3)10(S-Adm)5Cl2]2+ nanoclusters using kinetic controls. The complete molecular structure was determined by single-crystal X-ray crystallography and electrospray ionization mass spectrometry. In comparison with the previously reported [Au25(PPh3)10(PET)5Cl2]2+ clusters, both nanoclusters have an icosahedral composition of Au13 linked by Au atoms that share a vertex, but [Au25(PPh3)10(S-Adm)5Cl2]2+ clusters appear elongated due to the rigidity of adamantane. We conducted ultraviolet-visible spectrophotometry (UV-vis) measurements of [Au25(PPh3)10(PET)5Cl2]2+ and [Au25(PPh3)10(S-Adm)5Cl2]2+ in dichloromethane solvent to elucidate the modulation of the cluster properties of different ligands. The lowest energy absorption peak of [Au25(PPh3)10(S-Adm)5Cl2]2+ shifted to lower energies compared to the [Au25(PPh3)10(PET)5Cl2]2+ clusters in UV-vis measurements. Temperature-dependent absorption measurements revealed that [Au25(PPh3)10(S-Adm)5Cl2]2+ clusters were less affected by temperature compared to [Au25(PPh3)10(PET)5Cl2]2+. This result is attributed to the exciton phonon coupling of [Au25(PPh3)10(S-Adm)5Cl2]2+ clusters being weaker than [Au25(PPh3)10(PET)5Cl2]2+ clusters. Furthermore, the absorption spectra of [Au25(PPh3)10(PET)5Cl2]2+ and [Au25(PPh3)10(S-Adm)5Cl2]2+ clusters were measured using different types of solutions, and it was found that the lowest energy absorption peaks of [Au25(PPh3)10(S-Adm)5Cl2]2+ were shifted and affected by the solution at room temperature, which suggested that the [Au25(PPh3)10(S-Adm)5Cl2]2+ clusters with solution hydrogen bonds also interacted strongly at room temperature. Theoretical calculations show that changes in ligands affect the differences in the molecular orbitals and structures of the clusters, which cause changes in the optical properties.

Tuning the chemical composition of binary alloy nanoparticles to prevent their dissolution.

The dissolution of nanoparticles under corrosive environments represents one of the main issues in electrochemical processes. Here, a model for alloying and protecting nanoparticles from corrosion with an anti-corrosive element (e.g. Au) is proposed based on the hypothesis that under-coordinated atoms are the first atoms to dissolve. The model considers the dissolution of atoms with coordination number ≤6 on A-B nanoparticles with different sizes, shapes, chemical compositions, and exposed crystallographic orientations. The results revealed that the nanoparticle's size and chemical composition play a key role in the dissolution, suggesting that a certain composition of an element with corrosive resistance could be used to protect nanoparticles. DFT simulations were performed to support our model on the dissolution of four types of atoms commonly found on the surface of Au0.20Pd0.80 binary alloys - terrace, edge, kink, and ad atoms. The simulations suggest that the less coordinated ad and kink Pd atoms on Au0.20Pd0.80 alloys are dissolved in a potential window between 0.26-0.56 V, while the rest of the Pd and Au atoms are protected. Furthermore, to show that a corrosion-resistant element can indeed protect nanoparticles, we experimentally investigated the electrochemical dissolution of immobilized Pd, Au0.20Pd0.80, and Au0.40Pd0.60 nanoparticles in a harsh environment. In line with the dissolution model, the experimental results show that an Au molar fraction of the nanoparticle of 0.20, i.e., Au0.20Pd0.80 binary alloy, is a good compromise between maximizing the active surface area (Pd atoms) and corrosion protection by the inactive Au.

MOLECULAR STUDY OF CORE-SHELL RATIO EFFECT ON THERMOPHYSICAL PROPERTIES OF SIO2@AU-WATER NANOFLUID

Thermal conductivity (&amp;lambda;) and specific heat capacity (&lt;i&gt;c&lt;sub&gt;p&lt;/sub&gt;&lt;/i&gt;) are essential thermophysical properties related to thermal storage systems. Molecular simulations of the shell-to-total-radius ratios (&amp;Phi;) of SiO&lt;sub&gt;2&lt;/sub&gt;@ Au nanoparticle (NP) are used to investigate their impact on the &lt;i&gt;c&lt;sub&gt;p&lt;/sub&gt;&lt;/i&gt; and &amp;lambda; of water nanofluids (NFs) containing this NP. The roles of solid/liquid and solid/solid interfaces on &lt;i&gt;c&lt;sub&gt;p&lt;/sub&gt;&lt;/i&gt; and &amp;lambda; are identified by using the calculations of the vibrational density of state (VDOS) of the SiO&lt;sub&gt;2&lt;/sub&gt;@Au nanoparticle, the core (SiO&lt;sub&gt;2&lt;/sub&gt; molecule), the shell (Au atom), and the thin layer of water molecules next to the particle surface. The effects of core-shell NPs on the characteristics of the base fluid are further understood by using the VDOS mismatch between the NP and the thin water layer and the radial distribution function of water molecules. The heat current contribution is discussed to view the &amp;lambda; increase mechanism of NF. It is found that &lt;i&gt;c&lt;sub&gt;p&lt;/sub&gt;&lt;/i&gt; increases with increasing &amp;Phi;, while &amp;lambda; increases with decreasing &amp;Phi;. The convection component and the virial term consisting of the heat current are considerable contributions. New correlations are proposed for calculating the &lt;i&gt;c&lt;sub&gt;p&lt;/sub&gt;&lt;/i&gt; and &amp;lambda; of NFs containing core-shell NPs, thus explaining the contributions of the components to &lt;i&gt;c&lt;sub&gt;p&lt;/sub&gt;&lt;/i&gt; and &amp;lambda; of NFs. The study of the effect of &amp;Phi; on the thermophysical characteristics of these NFs provides molecular insight into the roles of the solid/liquid and solid/solid interfaces. These results contribute to the understanding of the thermophysical properties of core-shell NFs and their uses in solar thermal applications.

Non-volatile resistive switching mechanism in single-layer MoS2 memristors: insights from ab initio modelling of Au and MoS2 interfaces.

Non-volatile memristive devices based on two-dimensional (2D) layered materials provide an attractive alternative to conventional flash memory chips. Single-layer semiconductors, such as monolayer molybdenum disulphide (ML-MoS2), enable the aggressive downscaling of devices towards greater system integration density. The "atomristor", the most compact device to date, has been shown to undergo a resistive switching between its high-resistance (HRS) and low-resistance (LRS) states of several orders of magnitude. The main hypothesis behind its working mechanism relies on the migration of sulphur vacancies in the proximity of the metal contact during device operation, thus inducing the variation of the Schottky barrier at the metal-semiconductor interface. However, the interface physics is not yet fully understood: other hypotheses were proposed, involving the migration of metal atoms from the electrode. In this work, we aim to elucidate the mechanism of the resistive switching in the atomristor. We carry out density functional theory (DFT) simulations on model Au and ML-MoS2 interfaces with and without the presence of point defects, either vacancies or substitutions. To construct realistic interfaces, we combine DFT with Green's function surface simulations. Our findings reveal that it is not the mere presence of S vacancies but rather the migration of Au atoms from the electrode to MoS2 that modulate the interface barrier. Indeed, Au atoms act as conductive "bridges", thus facilitating the flow of charge between the two materials.

Theoretical study on mechanical evolution process of interface between gold electrode and pyridyl anchor group

Pyridyl-ended molecular junctions show high and low breaking forces successively in formation process and at the same time exhibit intriguing conductance switching behaviors. To understand the forming process of pyridyl-ended molecular junctions, the interaction between 4,4′-bipyridine molecule and gold electrode is studied by the &lt;i&gt;ab initio&lt;/i&gt;-based adiabatic simulation method. The processes that the molecule moves away from electrode tip with different contact configurations are simulated, and the molecule-electrode interface evolutions, energy of the molecule-electrode system and the force between molecules and electrode are calculated in the simulations. The numerical results show that during the molecule moving away from the pyramid-shaped electrode, the pyridyl is easy to vertically adsorb on the second gold layer of the electrode tip. In this contact configurations, the tip Au atom deviates from the original position due to the lateral pushing force of the pyridyl. It needs about 1.3–1.5 nN stretching force for the pyridyl breaking from the second gold layer and switching to the tip Au atom, which is evidently larger than the force of 0.8–1.0 nN for the molecule breaking from the tip Au atom. This result is well consistent with the experimental observations, which thus reveals the relationship between the interface structures and the stretching force in the formation process of bipyridyl molecular junction in the experiment. The interaction between 4,4′-bipyridine molecule and plane-shaped gold electrode is very weak. It needs no more than 0.5 nN for the molecule breaking from the plane-shaped gold electrode. However, when the molecule adsorbs on the single Au atom which is adsorbed on the surface of plane-shaped electrode, the molecule can sustain 1.7 nN stretching force. Our study shows that the &lt;i&gt;ab initio&lt;/i&gt;-based adiabatic stretching simulation method can not only reveal the geometric evolution process of molecule-electrode systems, but also identify the specific contact configurations between molecule and electrode.

Anti-bonding mediated record low and comparable-to-air lattice thermal conductivity of two metallic crystals

PbAuGa and CsKNa possess record low lattice thermal conductivity which is even comparable to that of air. The loosely bonded Au and Cs atoms in PbAuGa and CsKNa respectively act as intrinsic rattlers and thus induce strong phonon anharmonicity.

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.

Achieving high quantum capacitance graphdiyne through doping and adsorption.

In recent years, a new two-dimensional carbon material, graphdiyne (GDY), has attracted extensive attention in the field of energy storage, due to its unique topological and electronic structures, high charge mobility, and excellent electron transport properties. However, the disappearance of the density of states near the Fermi level leads to a low quantum capacitance (CQ) of pristine GDY, which limits its application in supercapacitors. Here, we propose doping and metal atom adsorption to be efficient ways to increase the CQ of GDY. Based on first-principles density functional theory, the effects of doping B, N, P, and S atoms and adsorbing Au, Ag, Cu, Ti, and Al atoms on the CQ of GDY are systematically investigated. The results show that the CQ of GDY can be significantly improved by introducing doping/adsorption, which could be a potential cathode material and anode material for supercapacitors. Our work provides an effective way for GDY to be applied as an efficient electrode material for supercapacitors.

Magnetic and optoelectronic modification of graphene-like ZnO monolayer by doping of Ag, Au and Pt atoms

The magnetic and optoelectronic properties of graphene-like ZnO monolayers (g-ZnO) doped with noble metal elements (NME: Ag, Au, and Pt) were investigated using density functional theory. It shows that the doping of NMEs can transfer the g-ZnO into magnetic material, regulate the band structure, decrease the band gap and the work function, making the g-ZnO semi-metallic. Consider the magnetic coupling of the dopant atoms, as the distance between two same doping atoms (Au or Pt) increases, the g-ZnO undergoes nonmagnetic to ferromagnetic or ferromagnetic to antiferromagnetic transitions. Additionally, the absorption spectrum demonstrates a red-shift phenomenon, expanding the absorption range of g-ZnO to the visible region. These promote the applications of NME-doped g-ZnO in spintronic devices and photocatalytic degradation. • Graphene liked ZnO monolayers (g-ZnO) doped with noble metal elements are studied by DFT calculations. • Ag, Au and Pt doping regulates the band structure, decreases the band gap and work function. • Ag, Au and Pt doping causes the g-ZnO magnetically transformed and shows semi-metallicity. • The magnetic coupling type of two doping atoms can be regulated by changing the distance between them. • Ag, Au and Pt doping expands the absorption region of g-ZnO into the visible light.

Ultra-low loading Pt atomic cluster electrode with Pt–O bond as an active site with high hydrogen evolution reaction performance

The oxidized Pt atomic cluster-supported Au electrode (PtAC–O–Au) with ultra-low loading exhibits a very high mass activity, and the active site is the oxidized platinum (Pt–O).

Homoleptic complexes of isocyano- and diisocyanobiazulenes with a 12-electron, ligand-based redox capacity.

Oligo- and polyazulenes are attractive π-conjugated building blocks in designing advanced functional materials. Herein, we demonstrate that anchoring one or both isocyanide termini of the redox non-innocent 2,2'-diisocyano-6,6'-biazulenic π-linker (1) to the redox-active [Cr(CO)5] moiety provided a convenient intramolecular redox reference for unambiguously establishing that the 6,6'-biazulenic scaffold undergoes a reversible one-step 2e- reduction governed by reduction potential compression/inversion. Treatment of bis(η6-naphthalene)chromium(0) with six equiv. of 2-isocyano-1,1',3,3'-tetraethoxycarbonyl-6,6'-biazulene (6) or [(OC)5Cr(η1-2,2'-diisocyano-1,1',3,3'-tetraethoxycarbonyl-6,6'-biazulene)] (11) afforded homoleptic Cr(0) complexes 13 and 14 with a 12e- (per molecule) ligand-based reduction capacity at mild E1/2 of -1.29 V and -1.15 V vs. Cp2Fe0/+, respectively. The overall reversible redox capacity varies from 15e- for the mononuclear complex 13 to 21e- for the heptanuclear complex 14. The latter "nanocomplex" has a diameter of ca. 5 nm and features seven Cr(0) centers interlinked with six 2,2'-diisocyano-6,6'-biazulenic bridges. The X-ray structure of [(OC)5Cr(2-isocyano-1,1',3,3'-tetraethoxycarbonyl-6,6'-biazulene)] (7) indicated a 43.5° interplanar angle between the two azulenic moieties. Self-assembly of 11 on a Au(111) substrate afforded an organometallic monolayer film of 11 featuring approximately upright orientation of the 2,2'-diisocyano-6,6'-biazulenic linkers, as evidenced by ellipsometric measurements and the RAIR signature of the C4v-symmetric [(-NC)Cr(CO)5] infrared reporter within 11. Remarkably, comparing the FTIR spectrum of 11 in solution with the RAIR spectrum of 11 adsorbed on Au(111) suggested electronic coupling at a ca. 2 nm distance between the Cr(0) and Au atoms linked by the 2,2'-diisocyano-6,6'-biazulene bridge.