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Metal-free catalytic conversion of CO2 is expected to achieve carbon neutrality. However, non-metallic catalytic sites for highly selective and efficient conversion of CO2 to ethanol are challenging. Here, a metal-free catalyst (B4@g-C3N4) has been reported for the first time for the efficient reduction of CO to ethanol. Utilizing electron "accept-donation" analysis, we show that the binding of tri-coordinated B atoms to CO is very mild compared to metal sites and bi-coordinated B atoms. The B4@g-C3N4 catalyst effectively reduced the free energy barrier for direct dimerization of CO to 0.18 eV. The limiting voltage in the entire reduction of CO to CH3HC2OH is −0.19 V, which is better than that of other catalysts, including four-atom metal clusters Cu4–C5N2H2 (−0.50 V) and Cu2Zn2–C5N2H2 (−0.46 V) just proposed (J. Am. Chem. Soc. 2023, 145, 7030–7039). The metal-free electrocatalyst has an absolute selectivity advantage since the molar ratio of the C2 product CH3CH2OH to the C1 product CH4 is 2.55 × 105 : 1. Moreover, due to its extremely high stability, the catalyst designed in this paper holds great promise for synthesis. The above analysis shows that the B4@g-C3N4 catalyst constructed under the new concept proposed by us can achieve the goal of electrocatalytic CO reduction to ethanol. Our work reports the first metal-free electrocatalyst to date for the reduction of CO to ethanol, providing a theoretical basis for promoting the achievement of sustainable carbon neutrality goals. [ABSTRACT FROM AUTHOR]

A promising pathway for carbon usage and energy storage is electrocatalytic reduction of CO to form high-value multi-carbon products. Herein, the d–p coupled triatomic catalyst CuB2@g-C3N4 with significant activity and selectivity for ethanol is presented for the first time. Density functional theory calculations elucidate that these spatially confined triatomic centers are capable of immobilizing multiple CO molecules, providing an exclusive reaction channel for direct C–C coupling. The CuB2@g-C3N4 catalyst can effectively reduce the energy barrier of CO dimerization to 0.46 eV. The limiting potential is only −0.19 V, which is much smaller than that of other Cu-based catalysts. Additionally, the CuB2@g-C3N4 catalyst can effectively inhibit the generation of competing C1 products and hydrogen evolution reactions. Excitingly, CuB2 loading makes g-C3N4 more optically active in visible and even infrared light. This work provides important ideas for the atomically precise design of novel d–p coupled catalysts for the direct conversion of CO2/CO into energetic fuels and high-value chemicals. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) calculations are executed to investigate the effect of a potassium (K) promoter on the activity of the water gas shift reaction (WGSR) over an Ag(111) surface. It is found that the WGSR proceeds mainly through the OH(O)-assisted carboxy pathway in which H2O dehydrogenation is the rate-controlling step on both Ag(111) and K/Ag(111) surfaces. Energetic span model analysis shows that K addition can enhance the activity of the WGSR by reducing the apparent activation energy of the whole reaction since it can promote H2O dissociation and stabilize the adsorption of the reactants (CO and H2O). Importantly, the K adatom can stabilize the binding of all oxygenates by direct K–O bonding and the stabilizing effect of K on OH adsorption of the transition state (TS) plays a leading role in promoting H2O dissociation. Moreover, the K–O distance and K coverage are two key factors affecting H2O activation, that is, the shorter the K–O distance (2–3 Å) the more the K coverage (25%) contributes to the stronger promotion effect. For various metals catalyzing the WGSR, K promotes H2O dissociation on inert metals like Ag, Au and Cu better than those on reactive metals (Pd and Ni) since the more inert metal surfaces would weaken the K and O binding and accordingly strengthen the interaction between them, resulting in a higher promotion effect. [ABSTRACT FROM AUTHOR]

The photoelectron detachment of nickel carbide anions has been characterized using photoelectron velocity-map imaging spectroscopy, allowing for a precise assignment of the electron affinity, vibrational frequencies, energy spacing and ordering of the low-lying electronic states. Additional insight into the chemical bonding and electronic structure of ground-state NiC has been achieved by a range of quantum chemical calculations. It is found that the triple-bonded 1Σ+ ground state probably mainly correlates with the Ni 3d94s1 state, so the triple bonds are better described as involving one electron-sharing σ bond, one electron-sharing π bond, and one Ni → C dative π bond. [ABSTRACT FROM AUTHOR]

Two novel complexes were constructed by adsorption of two typical organic molecules, including one electron-donating molecule (TTF = tetrathiafulvalene) and one electron-withdrawing molecule (TCNQ = tetracyanoquinodimethane), on the surface of black phosphorus quantum dots (BPQDs). There exist considerable charge transfer and strong non-covalent interaction between organic molecules and BPQDs. The results of density functional theory (DFT) calculations show that the static first and second hyperpolarizabilities can be significantly enhanced by introducing TTF/TCNQ groups on BPQDs. Apart from static nonlinearity, hyper-Rayleigh scattering (HRS) first hyperpolarizability shows a remarkable value at a dispersion frequency of 1907 nm. Besides, the frequency-dependent first hyperpolarizability increases significantly while going from the gas to solvent phase. BPQDs–TTF presents a strong dipolar character, whereas BPQDs–TCNQ presents a relatively larger octupolar behavior. Compared with BPQDs–TTF, BPQDs–TCNQ exhibits better stability and larger first hyperpolarizability. This work highlights the superiority of combining TCNQ and BPQDs to construct high-performance nonlinear optical (NLO) molecules. [ABSTRACT FROM AUTHOR]

The heterodinuclear silver tetracarbonyl-iron anion was generated in the gas phase and studied by joint photoelectron velocity map imaging spectroscopy and quantum chemical calculations. The AgFe(CO)4− anion is characterized to be an 18-electron complex with the silver atom covalently bonded to the anionic tetracarbonyl-iron, an isolobal analogue of the methyl radical. The bonding analyses using a range of state-of-the-art quantum chemistry methods revealed a peculiar decentralized bonding situation, where the silver atom is covalently bonded to both the iron center and the vicinal carbon atoms in the form of an electron-sharing σ bond. [ABSTRACT FROM AUTHOR]

The growth patterns and electronic structures of Aun clusters (n = 1–16) supported on the monoclinic ZrO2(111) surface were investigated using a DFT+U approach. We found that the supported Aun clusters prefer quasi-planar structures and lay flat on the ZrO2 surface. This result agrees well with the experimental results. Both orbital overlap and dispersion interactions contribute to the interaction between the Aun cluster and the ZrO2 surface. Electrons were transferred from the ZrO2 surface to the Aun cluster. Small energy gaps between unoccupied states in the Aun clusters and occupied states in the ZrO2 surface were found, especially for the supported Aun clusters with odd n, which may indicate that more electrons are excited from the ZrO2 surface to the Aun cluster even under visible-light irradiation. In other words, the ZrO2 support may be involved in the photocatalytic process when Aun/ZrO2 is used as a photocatalyst. [ABSTRACT FROM AUTHOR]

The non-classical KP6Mo18O73heteropolyanion has been studied by the density functional theory (DFT) method, and the calculated geometry compares well with the experimental one. In fully oxidized [KP6Mo18O73]7−state, the dxy-orbitals centered at eight “belt” Mo sites in the lower part of the “basket” are the major contributors to the LUMO and LUMO+1, while the LUMO+2 orbital is mostly focused on the two polar parts. In contrast, the HOMOs indicates that the coordination of the KP6Mo18heteropolyanion to metal ions favorably occurs at the oxygen atoms from four external phosphates and two molybdates of the handle of the “basket”. Compared with Wells–Dawson [P2Mo18O62]6−, the HOMO–LUMO gap in fully oxidized [KP6Mo18O73]7−is much smaller, indicating much easier reduction that is consistent with the cyclic voltammogram. Both frontier orbitals and Mulliken analysis indicate that two of three blue electrons in [KP6Mo18O73]10−(KP6Mo18-3e) have spin alpha while third blue electron has spin beta, in agreement with magnetic data. The four-copper complex of the non-classical KP6Mo18-3e heteropolyanion has been synthesized and structurally characterized; its structure supports the theoretical results such as reactivity and basicity of external oxygen sites. [ABSTRACT FROM AUTHOR]

The non-classical KP6Mo18O73heteropolyanion has been studied by the density functional theory (DFT) method, and the calculated geometry compares well with the experimental one. In fully oxidized [KP6Mo18O73]7−state, the dxy-orbitals centered at eight “belt” Mo sites in the lower part of the “basket” are the major contributors to the LUMO and LUMO+1, while the LUMO+2 orbital is mostly focused on the two polar parts. In contrast, the HOMOs indicates that the coordination of the KP6Mo18heteropolyanion to metal ions favorably occurs at the oxygen atoms from four external phosphates and two molybdates of the handle of the “basket”. Compared with Wells–Dawson [P2Mo18O62]6−, the HOMO–LUMO gap in fully oxidized [KP6Mo18O73]7−is much smaller, indicating much easier reduction that is consistent with the cyclic voltammogram. Both frontier orbitals and Mulliken analysis indicate that two of three blue electrons in [KP6Mo18O73]10−(KP6Mo18-3e) have spin alpha while third blue electron has spin beta, in agreement with magnetic data. The four-copper complex of the non-classical KP6Mo18-3e heteropolyanion has been synthesized and structurally characterized; its structure supports the theoretical results such as reactivity and basicity of external oxygen sites. [ABSTRACT FROM AUTHOR]

An ionothermal reaction has generated a cobalt hydroxyacetate magnet that contains a three-dimensional Co–O–Co framework consisting of vertex-sharing octahedral chains bridged by another octahedra viaedge-sharing and shows spin glass behavior. [ABSTRACT FROM AUTHOR]

A promising pathway for carbon usage and energy storage is electrocatalytic reduction of CO to form high-value multi-carbon products. Herein, the d-p coupled triatomic catalyst CuB 2 @g-C 3 N 4 with significant activity and selectivity for ethanol is presented for the first time. Density functional theory calculations elucidate that these spatially confined triatomic centers are capable of immobilizing multiple CO molecules, providing an exclusive reaction channel for direct C-C coupling. The CuB 2 @g-C 3 N 4 catalyst can effectively reduce the energy barrier of CO dimerization to 0.46 eV. The limiting potential is only -0.19 V, which is much smaller than that of other Cu-based catalysts. Additionally, the CuB 2 @g-C 3 N 4 catalyst can effectively inhibit the generation of competing C1 products and hydrogen evolution reactions. Excitingly, CuB 2 loading makes g-C 3 N 4 more optically active in visible and even infrared light. This work provides important ideas for the atomically precise design of novel d-p coupled catalysts for the direct conversion of CO 2 /CO into energetic fuels and high-value chemicals.

Density functional theory (DFT) calculations are executed to investigate the effect of a potassium (K) promoter on the activity of the water gas shift reaction (WGSR) over an Ag(111) surface. It is found that the WGSR proceeds mainly through the OH(O)-assisted carboxy pathway in which H 2 O dehydrogenation is the rate-controlling step on both Ag(111) and K/Ag(111) surfaces. Energetic span model analysis shows that K addition can enhance the activity of the WGSR by reducing the apparent activation energy of the whole reaction since it can promote H 2 O dissociation and stabilize the adsorption of the reactants (CO and H 2 O). Importantly, the K adatom can stabilize the binding of all oxygenates by direct K-O bonding and the stabilizing effect of K on OH adsorption of the transition state (TS) plays a leading role in promoting H 2 O dissociation. Moreover, the K-O distance and K coverage are two key factors affecting H 2 O activation, that is, the shorter the K-O distance (2-3 Å) the more the K coverage (25%) contributes to the stronger promotion effect. For various metals catalyzing the WGSR, K promotes H 2 O dissociation on inert metals like Ag, Au and Cu better than those on reactive metals (Pd and Ni) since the more inert metal surfaces would weaken the K and O binding and accordingly strengthen the interaction between them, resulting in a higher promotion effect.

The heterodinuclear silver tetracarbonyl-iron anion was generated in the gas phase and studied by joint photoelectron velocity map imaging spectroscopy and quantum chemical calculations. The AgFe(CO)4- anion is characterized to be an 18-electron complex with the silver atom covalently bonded to the anionic tetracarbonyl-iron, an isolobal analogue of the methyl radical. The bonding analyses using a range of state-of-the-art quantum chemistry methods revealed a peculiar decentralized bonding situation, where the silver atom is covalently bonded to both the iron center and the vicinal carbon atoms in the form of an electron-sharing σ bond.

The growth patterns and electronic structures of Au n clusters (n = 1-16) supported on the monoclinic ZrO 2 (111) surface were investigated using a DFT+U approach. We found that the supported Au n clusters prefer quasi-planar structures and lay flat on the ZrO 2 surface. This result agrees well with the experimental results. Both orbital overlap and dispersion interactions contribute to the interaction between the Au n cluster and the ZrO 2 surface. Electrons were transferred from the ZrO 2 surface to the Au n cluster. Small energy gaps between unoccupied states in the Au n clusters and occupied states in the ZrO 2 surface were found, especially for the supported Au n clusters with odd n, which may indicate that more electrons are excited from the ZrO 2 surface to the Au n cluster even under visible-light irradiation. In other words, the ZrO 2 support may be involved in the photocatalytic process when Au n /ZrO 2 is used as a photocatalyst.

The non-classical KP(6)Mo(18)O(73) heteropolyanion has been studied by the density functional theory (DFT) method, and the calculated geometry compares well with the experimental one. In fully oxidized [KP(6)Mo(18)O(73)](7-) state, the d(xy)-orbitals centered at eight "belt" Mo sites in the lower part of the "basket" are the major contributors to the LUMO and LUMO+1, while the LUMO+2 orbital is mostly focused on the two polar parts. In contrast, the HOMOs indicates that the coordination of the KP(6)Mo(18) heteropolyanion to metal ions favorably occurs at the oxygen atoms from four external phosphates and two molybdates of the handle of the "basket". Compared with Wells-Dawson [P(2)Mo(18)O(62)](6-), the HOMO-LUMO gap in fully oxidized [KP(6)Mo(18)O(73)](7-) is much smaller, indicating much easier reduction that is consistent with the cyclic voltammogram. Both frontier orbitals and Mulliken analysis indicate that two of three blue electrons in [KP(6)Mo(18)O(73)](10-) (KP(6)Mo(18)-3e) have spin alpha while third blue electron has spin beta, in agreement with magnetic data. The four-copper complex of the non-classical KP(6)Mo(18)-3e heteropolyanion has been synthesized and structurally characterized; its structure supports the theoretical results such as reactivity and basicity of external oxygen sites.

An ionothermal reaction has generated a cobalt hydroxyacetate magnet that contains a three-dimensional Co-O-Co framework consisting of vertex-sharing octahedral chains bridged by another octahedra via edge-sharing and shows spin glass behavior.

Two salts and seven copper(I/II) and silver(I) coordination polymers containing tetrazolyl ligands have been hydro(solvo)thermal synthesized by metal salts, NaN3 and various nitriles generated via [2 + 3] cycloaddition reactions of organonitriles and sodium azide. The study also shows that in some cases the azide can play a dual role in the in situ syntheses of metal tetrazole complexes, namely, starting material for tetrazole ligand and co-ligand in the tetrazole-based coordination complexes. Compounds and are simple salts of ammonium and sodium 5-methyltetrazolate. Compound has a 3-D framework with intersecting channel and unprecedented (4(9).6(6)) topology constructed from mixed-valent Cu8 clusters. Compounds and are isomorphous, and have 3-D organic-inorganic frameworks constructed by [M2(mtta)]+ (Hmtta = 5-methyltetrazole) ribbon and [M2(N3)]+ (M = Cu, Ag) layer two types of structural motifs, which contains an mu(4)-1,1,1,3 azide. Compound is a 3-D four-connected chiral complex with (4(2).8(4))(Cu)(4(2).8(2).10(2))(tta) topology. The structure of consists of 2-D three-connected layers that are linked by ligand-unsupported Ag(I)...Ag(I) interactions to form a 3-D supramolecular array. Compound shows a 3-D chiral framework containing tetrahedrally and linearly coordinated Ag(I) ions and mu3- and mu4-two types of 5-propyltetrazolate. Compound has a 2-D layered structure formed by linkage of [Ag(tetrazolyl)] ribbons via C-C and N-Ag bonds. Magnetic measurement confirmed that there are two Cu(II) ions and six Cu(I) ions per Cu8 unit consistent with a mixed-valent Cu(I,II) complex.

The first coordination polymer of 2,2'-oxydisuccinate, [Cd(2)(meso-odsc)(H(2)O)](odsc =meso-2,2'-oxydisuccinate), was hydrothermally synthesized from CdSO(4) and D,L-malic acid; X-ray crystallography shows that the D,L-malic acid was transformed in situ into meso-odsc via intermolecular dehydration coupling.

The novel basket-shaped three-electron-reduced heteropoly blue [H2dmpip]5[K [subset or is implied by] P6Mo18O73] was prepared and characterized; it shows reversible one-electron redox properties., (Copyright 2004 The Royal Society of Chemistry)