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This study investigated the electronic structure of single-atom Rhodium (Rh) and Iridium (Ir) adsorbed on defective and impurity-doped ZnO(0001) surfaces, and assessed their activity towards the CO oxidation reaction. Our findings reveal that surface impurities significantly influence the binding energies and electronic properties of the metal atoms, with Al and Cr serving as particularly effective promoters. While Rh and Ir acquire a positive charge upon incorporation on the unpromoted Zn(0001) surface, adsorption directly on the promoter results in a net negative charge, thus facilitating the activation of both CO and O2 species. These results highlight the potential of impurity-promoted ZnO surfaces in modulating and tailoring the electronic properties of SACs, which can be used for a rational design of active single-atom catalysts. [ABSTRACT FROM AUTHOR]

CO oxidation has been studied for more than a century; however, molecular-level understanding of its activation protocol and related intermediates remains elusive. Here, we present a unified mechanistic and kinetic picture of various electronic metal-support interactions within platinum-carbon catalysts via in situ spectroscopic/kinetic analyses and multi-scale simulations. Transient kinetic analysis and molecular dynamics simulations with a reactive force field provided a quantitative description of the competition between the oxygen association and oxygen dissociation mechanisms tuned by the interfacial charge distribution and CO coverage. Steady-state isotopic transient kinetic analysis and density functional theory calculations revealed a simultaneous shift in the rate-determining step (RDS) from O2 * dissociation to O* and CO* and O2 * and CO* association. A de novo strategy from the interfacial charge distribution to the reaction mechanism, kinetics/thermodynamics of RDS, and, ultimately, catalytic performance was developed to quantitatively map the above CO activation mechanism with an order-of-magnitude increase in reactivity. The proposed catalytic picture and de novo strategy are expected to prompt the development of theories and methodologies for heterogeneous catalysis. [ABSTRACT FROM AUTHOR]

A cationic copper‐stabilized coppoborylene was prepared and structurally characterized via infrared photodissociation spectroscopy and density functional theory calculations. This structure exemplifies a new class of borylenes stabilized by three‐center‐two‐electron metal‐boron‐metal covalent bonding interaction, displaying exceptional σ‐acidity and unparalleled π‐donor capability for CO activation that outperforms all of the known transition metal cations and is comparable or even superior to the documented base‐trapped borylenes. Its neutral form represents a monovalent boron compound with a strongly reactive amphoteric boron center built on transition‐metal‐boron bonds, which inspires the design and synthesis of new members of the borylene family. [ABSTRACT FROM AUTHOR]

Fe-based and Co-based catalysts are the most ideal Fischer-Tropsch synthesis catalysts. With the rapid development of computer simulation technology in the field of catalysis, it is possible to deeply understand the microscopic reaction mechanism on the surface of Fe-based and Co-based catalysts. Theoretical calculation method was used to study the effects of surface structures of Fe-based (reaction conditions: temperature 320 °C, pressure 1 MPa and n(H2):n(CO) = 1:1) and Co-based (reaction conditions: temperature 240 °C, pressure 1 MPa and n(H2):n(CO) = 2:1) Fischer-Tropsch synthesis catalysts with different H coverages on the activation and dissociation of CO. The thermodynamically preferred H-covered surface models of Fe-based and Co-based Fischer-Tropsch synthesis catalysts were determined through the linear relationships between the hydrogen chemical potential and the Gibbs free energy of hydrogen adsorption, which is the X-Fe5C2(510) surface with H coverage of 11/42 and HCP Co(0001) surface with H coverage of 24/36, respectively. The CO dissociation mechanism and corresponding reaction energy barriers on the clean surface and the H-covered surface of catalysts were studied, and it is found that H coverage can change the reaction pathways of CO dissociation and increase the dissociation energy barrier. Compared with the clean surfaces of X-Fe5C2(510) and HCP Co(0001), the dissociation energy barriers of CO on H-covered X-Fe5C2(510) and HCP Co(0001) surfaces increase by 5.4% and 20.3%, respectively. The origin reasons for the effects of H coverage on CO activation and dissociation were explained by calculating the density of states and crystal orbitals Hamiltonian population. [ABSTRACT FROM AUTHOR]

The geometric structure and bonding features of dinuclear vanadium-group transition metal carbonyl cation complexes in the form of VM(CO)n+ (n = 9–11, M = V, Nb, and Ta) are studied by infrared photodissociation spectroscopy in conjunction with density functional calculations. The homodinuclear V2(CO)9+ is characterized as a quartet structure with CS symmetry, featuring two side-on bridging carbonyls and an end-on semi-bridging carbonyl. In contrast, for the heterodinuclear VNb(CO)9+ and VTa(CO)9+, a C2V sextet isomer with a linear bridging carbonyl is determined to coexist with the lower-lying CS structure analogous to V2(CO)9+. Bonding analyses manifest that the detected VM(CO)9+ complexes featuring an (OC)6M–V(CO)3 pattern can be regarded as the reaction products of two stable metal carbonyl fragments, and indicate the presence of the M–V d-d covalent interaction in the CS structure of VM(CO)9+. In addition, it is demonstrated that the significant activation of the bridging carbonyls in the VM(CO)9+ complexes is due in large part to the diatomic cooperation of M–V, where the strong oxophilicity of vanadium is crucial to facilitate its binding to the oxygen end of the carbonyl groups. The results offer important insight into the structure and bonding of dinuclear vanadium-containing transition metal carbonyl cluster cations and provide inspiration for the design of active vanadium-based diatomic catalysts. [ABSTRACT FROM AUTHOR]

This study investigated the electronic structure of single-atom Rhodium (Rh) and Iridium (Ir) adsorbed on defective and impurity-doped ZnO(0001) surfaces, and assessed their activity towards the CO oxidation reaction. Our findings reveal that surface impurities significantly influence the binding energies and electronic properties of the metal atoms, with Al and Cr serving as particularly effective promoters. While Rh and Ir acquire a positive charge upon incorporation on the unpromoted Zn(0001) surface, adsorption directly on the promoter results in a net negative charge, thus facilitating the activation of both CO and O2 species. These results highlight the potential of impurity-promoted ZnO surfaces in modulating and tailoring the electronic properties of SACs, which can be used for a rational design of active single-atom catalysts.

The activation of CO on iron-based materials is a key elementary reaction for many chemical processes. We investigate CO adsorption and dissociation on a series of Fe, Fe3C, Fe5C2, and Fe2C catalysts through density functional theory calculations. We detect dramatically different performances for CO adsorption and activation on diverse surfaces and sites. The activation of CO is dependent on the local coordination of the molecule to the surface and on the bulk phase of the underlying catalyst. The bulk properties and the different local bonding environments lead to varying interactions between the adsorbed CO and the surface and thus yielding different activation levels of the C–O bond. We also examine the prediction of CO adsorption on different types of Fe-based catalysts by machine learning through linear regression models. We combine the features originating from surfaces and bulk phases to enhance the prediction of the activation energies and perform eight different linear regressions utilizing the feature engineering of polynomial representations. Among them, a ridge linear regression model with 2nd-degree polynomial feature generation predicted the best CO activation energy with a mean absolute error of 0.269 eV. [ABSTRACT FROM AUTHOR]

The geometric structure and bonding features of dinuclear vanadium-group transition metal carbonyl cation complexes in the form of VM(CO)n+ (n = 9–11, M = V, Nb, and Ta) are studied by infrared photodissociation spectroscopy in conjunction with density functional calculations. The homodinuclear V2(CO)9+ is characterized as a quartet structure with CS symmetry, featuring two side-on bridging carbonyls and an end-on semi-bridging carbonyl. In contrast, for the heterodinuclear VNb(CO)9+ and VTa(CO)9+, a C2V sextet isomer with a linear bridging carbonyl is determined to coexist with the lower-lying CS structure analogous to V2(CO)9+. Bonding analyses manifest that the detected VM(CO)9+ complexes featuring an (OC)6M–V(CO)3 pattern can be regarded as the reaction products of two stable metal carbonyl fragments, and indicate the presence of the M–V d-d covalent interaction in the CS structure of VM(CO)9+. In addition, it is demonstrated that the significant activation of the bridging carbonyls in the VM(CO)9+ complexes is due in large part to the diatomic cooperation of M–V, where the strong oxophilicity of vanadium is crucial to facilitate its binding to the oxygen end of the carbonyl groups. The results offer important insight into the structure and bonding of dinuclear vanadium-containing transition metal carbonyl cluster cations and provide inspiration for the design of active vanadium-based diatomic catalysts.

This work reports the synthesis, characterization, and reactivity of the first example of a well‐defined zinc α‐diazoalkyl complex. Treatment of zinc(I)‐zinc(I) bonded compound L2Zn2 [L=CH3C(2,6‐iPr2C6H3N)CHC(CH3)(NCH2CH2PPh2)] or zinc(II) hydride LZnH with trimethylsilyldiazomethane affords zinc diazoalkyl complex LZnC(N2)SiMe3. This complex liberates N2 in the presence of a nickel catalyst to form an α‐zincated phosphorus ylide by reacting with the pendant phosphine. It selectively undergoes formal [3+2] cycloaddition with CO2 or CO to form the corresponding product with a five‐membered heterocyclic core. Notably, the use of CO in such a [3+2] cycloaddition reaction is unprecedented, reflecting a novel CO reaction mode. [ABSTRACT FROM AUTHOR]

The process of Fischer–Tropsch synthesis is commonly described as a series of reactions in which CO and H2 are dissociated and adsorbed on the metals and then rearranged to produce hydrocarbons and H2O. However, CO dissociation adsorption is regarded as the initial stage of Fischer–Tropsch synthesis and an essential factor in the control of catalytic activity. Several pathways have been proposed to activate CO, namely direct CO dissociation, activation hydrogenation, and activation by insertion into growing chains. In addition, H2O is considered an important by-product of Fischer–Tropsch synthesis reactions and has been shown to play a key role in regulating the distribution of Fischer–Tropsch synthesis products. The presence of H2O may influence the reaction rate, the product distribution, and the deactivation rate. Focus on H2O molecules and H2O-derivatives (H*, OH* and O*) can assist CO activation hydrogenation on Fe- and Co-based catalysts. In this work, the intermediates (C*, O*, HCO*, COH*, COH*, CH*, etc.) and reaction pathways were analyzed, and the H2O and H2O derivatives (H*, OH* and O*) on Fe- and Co-based catalysts and their role in the Fischer–Tropsch synthesis reaction process were reviewed. [ABSTRACT FROM AUTHOR]

[Display omitted] • CO dissociation is the rate-determining step. • CO dissociation can occur via H-assistance through Rh-bound CH 3 O species. • Stabilized, dense CO adlayer forms on Rh surface upon thermal activation. • CO coverage on Rh protects formed oxygenates from immediate decomposition. The Rh-catalyzed CO hydrogenation to hydrocarbons and C 2 -oxygenates over Rh/ZrO 2 and Rh/SiO 2 was studied. Catalytic reaction tests show a support effect with a faster steady state reaction rate over Rh/ZrO 2 compared to Rh/SiO 2. Temperature programmed hydrogenation (TPH) experiments reveal that the CO dissociation on the metal surface is rate limiting, and the support effect thus accelerates the CO dissociation on the metal. Combined TPH and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) studies after low-temperature CO pre-adsorption reveal a H-assisted C-O bond breakage through CH 3 O species on the Rh surface. Transient measurements indicate that this mechanism is also likely to be in operation during the steady state reaction at higher temperatures, although here the methoxide is too short-lived to be detected at steady state. This hydrogen-assisted CO activation can help to explain that previous studies have observed an inverse H/D isotope effect for Rh despite CO dissociation being the rate limiting step. TPH studies show that both CO pre-adsorption at 30 ℃ and CO/H 2 exposure at 250 ℃ lead to so high CO coverages that it restricts the CO activation, which only starts once part of the CO has desorbed. The near-complete CO coverage on the working Rh surface is restricting the rate, but is essential for the selectivity towards oxygenates. Studies of acetaldehyde conversion in various atmospheres over Rh/SiO 2 and Rh/ZrO 2 catalysts show that acetaldehyde decomposes over a bare Rh surface with a rate that greatly exceeds the oxygenate formation rate in CO hydrogenation. In the presence of CO the acetaldehyde decomposition is strongly inhibited. The high CO coverage on the surface of the working Rh catalysts thus prevents oxygenate decomposition and is therefore essential for the ability to produce oxygenated products. The reaction temperature is observed to play a role for the establishment of the high coverage. During exposure to CO/H 2 at reaction temperatures (>200 ℃) an activated process occurs whereby both the stability and coverage of the CO adlayer increases. This activated stabilization of the CO adlayer shifts the CO activation up in temperature in a subsequent TPH. The results contribute to a fundamental understanding of the reaction mechanism and support effects in the Rh-catalyzed CO hydrogenation, which can assist the formulation of improved Rh-based catalysts. The results, such as the identification of a H-assisted mechanism of CO hydrogenenation via methoxide, could also be of general relevance for the understanding of CO hydrogenation over other metals. [ABSTRACT FROM AUTHOR]

The process of Fischer–Tropsch synthesis is commonly described as a series of reactions in which CO and H2 are dissociated and adsorbed on the metals and then rearranged to produce hydrocarbons and H2O. However, CO dissociation adsorption is regarded as the initial stage of Fischer–Tropsch synthesis and an essential factor in the control of catalytic activity. Several pathways have been proposed to activate CO, namely direct CO dissociation, activation hydrogenation, and activation by insertion into growing chains. In addition, H2O is considered an important by-product of Fischer–Tropsch synthesis reactions and has been shown to play a key role in regulating the distribution of Fischer–Tropsch synthesis products. The presence of H2O may influence the reaction rate, the product distribution, and the deactivation rate. Focus on H2O molecules and H2O-derivatives (H*, OH* and O*) can assist CO activation hydrogenation on Fe- and Co-based catalysts. In this work, the intermediates (C*, O*, HCO*, COH*, COH*, CH*, etc.) and reaction pathways were analyzed, and the H2O and H2O derivatives (H*, OH* and O*) on Fe- and Co-based catalysts and their role in the Fischer–Tropsch synthesis reaction process were reviewed.

[Display omitted] • Co-precipitated ternary oxides ZrCeZnO x with various CeO 2 contents were prepared. • Doped CeO 2 enhanced oxygen vacancies concentration and decreased the particle size. • Doped CeO 2 promoted the ability of CO activation and H 2 dissociation. • CH 3 O* was the intermediate in syngas into light olefins over. Zr4Ce2Zn1/SAPO-34 catalyst. • Optimized conditions show 25.6 % of CO conversion and 78.6 % of olefins selectivity. Direct conversion of syngas into light olefins over bifunctional catalysts (metal oxide and zeolite) has attracted great attention in recent years. For this reaction, the adsorption and activation of CO and H 2 occur on metal oxide surface, thus the design of metal oxide is crucial. In this study, ternary oxides ZrCeZnO x with various CeO 2 contents were prepared by parallel coprecipitation method, and SAPO-34 zeolite (Si/Al = 0.125) was hydrothermally synthesized. The metal oxides were characterized by XRD, BET, TEM, SEM, XPS, CO-TPD, H 2 -TPD, TGA and in-situ DRIFTS. The addition of CeO 2 into Zr-Zn oxide shifted the diffraction peaks to lower values, and formed the Ce 0.5 Zr 0.5 O 2 solid solution as the Zr/Ce/Zn atomic ratio reached 4/4/1. As the CeO 2 content rose, the BET surface area increased while the metal oxide particle size decreased. Moreover, the addition of CeO 2 greatly enhanced the concentration of oxygen vacancies and the adsorption ability of CO and H 2. The in-situ DRIFTS confirmed that CH 3 O* was the intermediate. By optimizing the reaction conditions, ZrCeZnO x /SAPO-34 catalyst exhibited high CO conversion of 25.6 % and light olefins selectivity of 78.6 %. This study will contribute to the design of metal oxide for bifunctional catalyst for light olefins synthesis. [ABSTRACT FROM AUTHOR]

This work reports that the ZnO−ZnCr2O4 interface was constructed by tailoring the Zn/Cr ratio and the role of ZnO−ZnCr2O4 interface in activating CO molecule for the synthesis of lower olefins over a tandem catalyst was studied. A lower olefins selectivity of 71 % at a CO conversion of 34 % was achieving on Zn1Cr1&SAPO‐34. The presence of ZnO−ZnCr2O4 interface effectively reduces the activation energy of CO hydrogenation (from 51.8 kJ/mol to 33.6 kJ/mol) and subsequently leading to the triple increase of intrinsic activity. In situ DRIFTS and XPS studies demonstrate that the better catalytic activities of Zn1Cr1 catalyst are related to the presence of ZnO−ZnCr2O4 interface, which provides more oxygen vacancy sites for CO adsorption and activation. In this sense, the Zn1Cr1 catalyst with ZnO−ZnCr2O4 interface is more active than the simple physical mixture of ZnO and Cr2O3 catalyst separately and Zn1Cr2 catalyst. This work provides fundamental insights for a rational design of Zn−Cr based catalysts and even other heterogeneous catalysts by constructing oxide‐oxide interface. [ABSTRACT FROM AUTHOR]

• The heteronuclear DACs (MoX@NC) possesses higher catalytic ability than the homonuclear DACs (2X@NC). • Compared to the homonuclear DACs, the Bader charge indicates that the electronic interaction between Mo atom and other transition metals is enhanced for the heteronuclear DACs. • The synergistic effect of the heteronuclear DACs originates from the enhancement of the intermetallic interaction between Mo atom and other transition metals in dimer. In order to identify the synergistic effect in the heteronuclear double-atom catalysts (DACs) on CO activation, the homonuclear and heteronuclear DACs have been designed based on graphene supporter. And the three CO dissociation pathways have been considered using the density functional theory (DFT) calculation. It reveals that the heteronuclear DACs (MoX@NC) possesses higher catalytic ability than the homonuclear DACs (2X@NC) for CO activation. And the unpaired d -orbital electron plays a significant role on CO activation, which can change the magnetic moment of the DACs. The coordination atoms offer similar local coordination environment for the homonuclear and heteronuclear DACs. However, the Bader charge displays that there is a strong electronic interaction between Mo atom and other transition metals of dimer for the heteronuclear DACs. The synergistic effect of the heteronuclear DACs originates from the enhancement of the intermetallic interaction between the Mo atom and other transition metals. The work offers rational guideline for the synthesis of DACs with excellent catalytic performances, and has great potential for application in various catalytic fields. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • The impact of CoO phase in FTS is unraveled by combining theoretical calculations and experiments. • Downward shift of d-band center for CoO gives rise to difficulties in the adsorption and activation of CO. • The difference of catalytic characteristics between CoO and metallic Co is systematically analyzed. • A linear correlation between DFT-calculated energy difference and experimental selectivity change is identified. In cobalt-catalyzed Fischer-Tropsch synthesis (FTS), the active metallic cobalt phase always suffers from oxidation under FTS reaction conditions, leading to the coexistence of metallic cobalt and cobalt oxide (CoO) phases. However, there still exist contradictory views on the impact of CoO phase in FTS. Some researchers proposed that the oxidation of metallic Co to CoO causes the deactivation of cobalt-based FTS catalysts, while some held the view that CoO phase could act as the potential active phase in FTS. In this study, by combining theoretical calculations and experiments, we systematically investigated the fundamental FTS reactions including CO adsorption and activation, C-C coupling, and C x H y hydrogenation on CoO phase, and compared them with those on metallic cobalt phase, aiming at identifying the exact role of CoO, understanding how CoO influences the activity and selectivity, and unraveling the intrinsic mechanism that determines the catalytic behaviors of CoO phase in FTS. The results reveal that the CoO(2 0 0) crystal facet is the dominantly exposed surface structure for CoO phase under FTS reaction conditions. The d-band center of CoO(2 0 0) surface shifts downward in comparison with that of active metallic Co surface, which causes difficulties in adsorbing and activating CO and gives rise to high energy barriers for the dissociation of C-O bond. This determines the inactive nature of CoO phase in FTS reaction. As for the product selectivity, the CoO(2 0 0) surface restricts the C-C chain growth due to its higher barriers for C-C coupling, facile desorption ability for light olefins, and lower energy barrier for CH 4 formation compared with metallic cobalt, and consequently leads to the loss of selectivity to C 5+ hydrocarbons and enhancement of selectivity to light olefins and undesired methane. Moreover, a strong linear relationship between the experimental observed selectivity change and the DFT-calculated energy difference of CoO and metallic cobalt phases was found, validating the DFT-calculated results. This study provides a comprehensive understanding of the nature and intrinsic catalytic behaviors of CoO phase in cobalt-catalyzed FTS. [ABSTRACT FROM AUTHOR]

Schematic mechanism of Co-plated WC under different pH conditions. • A new Co self-activation strategy was proposed to trigger the electroless plating on the surface of WC, with the merits of low cost, easy operation and high purity. • The appropriate pH value of the plating solution was of vital importance for the electroless chemical plating reaction as a buffering agent and OH− content controller. • The reaction mechanism of Co-activated electroless plating was declared. In this study, Co nanoparticles were mixed with WC powders by electroless plating with a new non-precious-Co-activation strategy. By soaking WC powders in a mixed solution of cobalt sulfate heptahydrate and sodium hypophosphite and then heat treated at 220 °C, Co active sites were seeded on WC powders to activate the following electroless plating of Co. The effects of reaction conditions on the weight gain and plating rate during electroless plating process were systematically investigated. As is evidenced by results, when the temperature, concentration of CoSO 4 and NaH 2 PO 2 ·H 2 O, and pH were 80 °C, 50 g/L, 45 g/L and 11 respectively, WC was evenly coated with Co. Notably, the XPS characterization indicated the content of zero-valence Co was elevated obviously after the plating process due to the effective reduction from two-valence Co. [ABSTRACT FROM AUTHOR]

The knowledge of bond activation forms a cornerstone for modern chemistry, wherein symmetry rules of electronic activation lie in the heart of bond activation. However, the question as to how a chemical bond is activated remains elusive. By taking CO activated on Fe(100), herein, we have resolved the long‐standing fundamental question; we have found that excitations in the adsorbate feature the bond activation. We essentially have discovered contrasting electronic processes in respective σ and π electron systems of the adsorbed CO molecule. The σ electron system is involved in reversible hidden excitations/deexcitations between two occupied σ orbitals, whereas the π electron system is subject to irreversible π to π* excitations dispersed along the d‐band region, which is coupled to the rotational 2π electron couplings depending on the strength of molecule‐metal interactions. The σ excitations pertain to the Pauli repulsion mediated quantum nature with energy and entropy marked by the two energy levels, whereas the π to π* excitations fall into a new category of electronic excitations contributing to energy and entropy exchanges in a wide and continuous d‐band region. The findings that the internal states of the adsorbate are excited and that fundamental connections between the frontier orbitals and low‐lying orbitals are established as the molecule comes to the surface may open up new channels to realize more efficient bond activation and renew our thinking on probing the quantum mechanical nature of bond activation at surfaces with further possible impact on manipulation of orbital activation in femtochemistry and attochemistry. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Hydrogen-transfers favoured at 400 °C vs. 200 °C on both Ru flat and stepped surfaces. • Entropy-driven CO activation mechanism via the formation of CH 2 and H 2 O on step-edges identified. • CO activation via CH 2 and H 2 O on step-edges more feasible then the formyl mechanism on flat surfaces. • CH x hydrogenation to methane display lower free energy barriers compared to CO activation. Abstract The methanation reaction converting CO into CH 4 at ca. 400 °C is proposed to take place on uncoordinated surface sites (e.g. step-edges) of Ru catalysts because of the higher measured reactivity of stepped vs. flat single crystal metal surfaces. However, the reaction mechanisms occurring at step-edges remain unclear due to the limitations in modelling high temperatures processes by the common evaluation of potential energy surfaces by density functional theory calculations. Here, we show using ab initio molecular dynamics simulations on CO-covered Ru flat and stepped surfaces models at 400 °C that hydrogen-transfers favoured at elevated temperatures are crucial for both CO activation and CH x (x = 1, 2, 3) hydrogenation steps of the methanation reaction, especially at step-edges. [ABSTRACT FROM AUTHOR]

[Display omitted] • The catalytic ability of sing-atom catalysts to CO activation has a relationship with the unpaired d -electronic number (n ud) of doped transition metal. • Compared with TM-C 3 catalysts, N-modification can improve catalytic performance of single-atom catalysts for CO activation, and the Mo-N 3 catalysts is the best candidate. • The modest d -band center (ε d) and electron-enriching coordination environment are advantageous to improving the catalytic performance of sing-atom catalysts. In order to characterize the relationship between the unpaired d -electronic number (n ud) of doped transition metal and catalytic ability, CO dissociation pathway over the single-atom catalysts, graphene and N-modified graphene decorated with 3 d- and 4 d- transition metal, have been discussed by the density functional theory (DFT) method. It is indicated that single-atom catalysts decorated with ⅥB or ⅦB subgroup transition metal are more active than others for CO activation. From IIIB toⅠB subgroup, the activation barrier shows a clear trend of first decreasing and then increasing. Based on the d- electronic orbital arrangement of transition metal, it can be inferred that the greater the n ud value of doped transition metal, the higher the catalytic ability of single-atom catalysts. Moreover, the C = O bond length when CO adsorbed on single-atom catalysts confirm this result. Meanwhile, compared with TM-C 3 catalysts, N-modification can improve catalytic ability of single-atom catalysts, and the Mo-N 3 catalysts is the best candidate for CO activation. Moreover, the modest d -band center (ε d) and electron-enriching coordination environment are advantageous to improving the catalytic performance of single-atom catalysts. It offers theoretical guidance for the further research and design of single-atom catalysts. [ABSTRACT FROM AUTHOR]

Abstract: The borylene–carbonyl moiety in [bis(silylene)B(CO)][WBr(CO)5] shows diverse reactivity. Reduction, migration, and complete cleavage of CO have been observed at the boron center, leading to the formation of new types of borylenes. These reactions not only serve as new methods for the synthesis of various stable borylenes, but also demonstrate that main‐group‐element compounds can mimic the behavior of transition‐metal complexes. [ABSTRACT FROM AUTHOR]

The chemical bonding and electronic structure of heteronuclear metal-nickel carbonyls MNi(CO)n− (M = Sc, Y; n = 2-6) have been investigated by mass-selected photoelectron velocity map imaging spectroscopy and quantum chemical calculations. Two CO bonding modes (side-on-bonded and terminal carbonyls) are involved in the n = 2 cluster. The building block composed of three kinds of different CO modes (side-on-bonded, bridging, and terminal carbonyls) is favored at n = 3, the structure of which persists up to n = 6. The additional CO ligands are preferentially coordinated in the terminal mode to the Sc atom and then to the Ni atom in the larger clusters. The present findings would promote the understanding of CO molecule activation and chemisorbed CO molecules on metal surfaces. [ABSTRACT FROM AUTHOR]

Hierarchical micro-mesoporous carbons were synthesized through the combination of soft templating and sol-gel process, which employed Pluronic F127 as soft template and glucose as carbon source. The obtained carbons were characterized by X-ray diffraction, scanning electron microscope, transmission electron microscope and nitrogen adsorption/desorption for their morphology and textural properties, and then evaluated in the process of CO capture. The high specific surface area, large total pore volume and narrow pore size distribution could be easily obtained and tuned by this method. Moreover, the synthesized carbons were physically activated by CO to improve the CO adsorption capacity and effects of the activation temperature and activation time were systematically investigated. The specific surface area and the total pore volume of sample which was obtained under the optimal condition increased from 1413 m/g and 1.02 cm/g to 2543 m/g and 2.21 cm/g after CO activation. The sample also exhibited the value of CO adsorption varying from 2.32 mmol/g up to 3.60 mmol/g at 25 °C and 1.6 bar. [ABSTRACT FROM AUTHOR]

Under a CO atmosphere, the dihydrodiborene [(cAAC)HB=BH(cAAC)] underwent coordination of CO concomitant with reversible hydrogen migration from boron to the carbene carbon atom, as well as reversible CO insertion into the B=B bond. Heating the CO adduct resulted in two unusual cAAC ring-expansion products, one presenting a B=C bond to a six-membered 1,2-azaborinane-3-ylidene, the other an unprecedented nine-membered cyclic alkyne resulting from reductive cleavage of CO and spontaneous formation of a C≡C bond. [ABSTRACT FROM AUTHOR]

A systematic approach to model heterogeneous catalyst material and characterization at the atomic level is presented. Two examples are used to illustrate the concepts derived from those studies. They document the problems arising on the way to create such model systems and they also indicate possible solutions. The first example is connected with activation of CO at the rim of electron rich MgO (thin film-supported Au islands), and the second example aims at the creation of a model system for the Phillips catalyst for ethylene polymerization and, in particular, the creation of a hydroxylated silica support. [ABSTRACT FROM AUTHOR]

Nickel-based catalysts were prepared by co-precipitation method and applied for the CO conversion to synthetic natural gas. Two batches of catalysts were prepared with the different amount of Ni and were characterized by various techniques such as XRD, TPD, TPR, XPS, and TEM. Catalytic activity was studied under atmospheric pressure, a temperature of 350 °C, GHSV of 2000 h and N:CO:H = 4:1:4. Highest CO conversion achieved was 70 with 99 % selectivity to methane. The activity of catalysts depends on the nickel content and nickel dispersion. Selectivity to methane depends inversely on the concentration of weak and moderate strength basic sites. Comparable quantity of basic sites present over catalysts, the methane selectivity is observed to be similar but the CO conversion changed due to change in Ni content. Catalysts having equal amounts of Ni exhibited increase in CH selectivity with the decrease in basic sites. [ABSTRACT FROM AUTHOR]

The reaction of carbon dioxide with α-siloxy silanes assisted by cesium fluoride is studied by means of DFT calculations with the B97D functional. Different mechanistic models are examined, including explicit introduction of cationic counterions and solvent molecules. The reaction is confirmed to proceed through carbanionic intermediates generated by Brook rearrangement, a carbon-to-oxygen transfer of a silyl group. The cesium cation is shown to play a critical role in stabilizing the key transition state. [ABSTRACT FROM AUTHOR]