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Yajing Zhang

Bio: Yajing Zhang is an academic researcher from Shanghai University of Engineering Sciences. The author has contributed to research in topics: Dissociation (chemistry) & Adsorption. The author has an hindex of 3, co-authored 4 publications receiving 27 citations.

Papers
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Journal ArticleDOI
TL;DR: In this article, Van der Waals density functional theory (DFT) combined with micro-kinetic modeling is used to study CO oxidation on 12 M-Ni(111) SAAs and pure Ni (111) surfaces.

23 citations

Journal ArticleDOI
TL;DR: The barrier calculations show that the dissociation is difficult to occur on Cu-HKUST-1 kinetically due to the very large dissociation barrier, and the present study provides interesting targets for experimental synthesis and testing.
Abstract: To develop promising adsorbent candidates for adsorptive denitrogenation, we screened the adsorption of NO, NO₂, and NH₃ in 19 M-HKUST-1 (M = Be, Fe, Ni, Cr, Co, Cu, V, Zn, Mo, Mn, W, Sn, Ti, Cd, Mg, Sc, Ca, Sr, and Ba) systematically using first-principle calculations. Of these, four variants of M-HKUST-1 (M = Ni, Co, V, and Sc) yield more negative adsorption Gibbs free energy ΔGads than the original Cu-HKUST-1 for three adsorbates, suggesting stronger adsorbate binding. Ti-HKUST-1, Sc-HKUST-1, and Be-HKUST-1 are predicted to have the largest NO, NO₂, and NH₃ adsorption energies within the screened M-HKUST-1 series, respectively. With the one exception of NO₂ dissociation on V-HKUST-1, dissociative adsorption of NO, NO₂, and NH₃ molecules on the other considered M-HKUST-1 is energetically less favorable than molecular adsorption thermodynamically. The barrier calculations show that the dissociation is difficult to occur on Cu-HKUST-1 kinetically due to the very large dissociation barrier. Electronic analysis is provided to explain the bond nature between the adsorbates and M-HKUST-1. Note that the isostructural substitution of Cu to the other metals is a major simplification of the system, representing the ideal situation; however, the present study provides interesting targets for experimental synthesis and testing.

17 citations

Journal ArticleDOI
TL;DR: The LPDOS reveals that all of the considered interfaces exhibit metallic character and the stability of the interface is found to be related to the type of formed interfacial boundary and bond, the interfacial bond populations, and the interf facial bond numbers.
Abstract: The interfacial stability of copper/diamond directly affects its mechanical properties and thermal conductivity. The atomic structures and electronic properties of Cu/diamond and Cu/X/diamond interfaces have been identified to investigate the effect of interfacial additive X (X = Ni or N) on the low-index interfacial adhesion of copper/diamond composites. For unmodified composites, the interfacial stability decreases in the order of Cu(001)/diamond(001) > Cu(111)/diamond(111) > Cu(011)/diamond(011). The metallic interfacial additive Ni is found to enhance the Cu(011)/diamond(011) interfacial stability and exchange the interfacial stability sequence of (011) and (111) composites. The nonmetallic element N will promote the stability of Cu(111)/diamond(111) but not alter the stability order of the composites at different interface. To explain the origin of interfacial stability, a series of analyses on atomic structures and electronic properties have been carried out, including the identification of the type of formed interfacial boundary, the measurement of interfacial bond lengths, and the calculations of density of states, bond populations, and atomic charge. The stability of the interface is found to be related to the type of formed interfacial boundary and bond, the interfacial bond populations, and the interfacial bond numbers. The LPDOS reveals that all of the considered interfaces exhibit metallic character. The interfacial Ni additive is found to be an electron donor contributing the electrons to its bonded Cu and C atoms while interfacial N atom is an electron acceptor where it mainly accepts the electrons from its bonded Cu and C.

12 citations

Journal ArticleDOI
TL;DR: The pre-adsorbed ethylene at the interface was found to facilitate the nucleations from the even-sized supported Irn to odd-sized Irn clusters, but hindered the nucleation from the odd- sized IrnTo-Even-sizedIrn clusters.
Abstract: Comprehending the bond nature of ethylene-metal clusters at the atomic level is important for the design of nanocatalysts and their applications in the fields of fine chemistry and petroleum refining. The growth of Irn (n = 1–10) on γ–Al2O3(110) and ethylene adsorption on bare and γ–Al2O3(110)-supported Irn (n = 1–10) clusters were investigated using the density functional theory (DFT) approach. The mode stability of ethylene adsorption on the bare Irn clusters followed the order π > di-σ > B-T, with the exception of Ir8 where the π structure was less stable than the di-σ configuration. On supported Irn (n = 4–7 and 10) the stability sequence was π > di-σ > di-σ′ (at interface), while on supported Irn (n = 2, 3, 8, and 9) the sequence changed to di-σ > π > di-σ′ (at interface). Two-thirds of ethylene adsorption on the supported Irn clusters were weaker than its adsorption on the bare Irn clusters. The pre-adsorbed ethylene at the interface was found to facilitate the nucleation from the even-sized supported Irn to odd-sized Irn clusters, but hindered the nucleation from the odd-sized Irn to even-sized Irn clusters.

4 citations


Cited by
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Journal ArticleDOI
TL;DR: This Review canvases approaches to date to explore reactivity and electron transfer using periodic, molecular, and embedded models, with emphasis placed on the application of electronic structure theory.
Abstract: Owing to their molecular building blocks, yet highly crystalline nature, metal-organic frameworks (MOFs) sit at the interface between molecule and material. Their diverse structures and compositions enable them to be useful materials as catalysts in heterogeneous reactions, electrical conductors in energy storage and transfer applications, chromophores in photoenabled chemical transformations, and beyond. In all cases, density functional theory (DFT) and higher-level methods for electronic structure determination provide valuable quantitative information about the electronic properties that underpin the functions of these frameworks. However, there are only two general modeling approaches in conventional electronic structure software packages: those that treat materials as extended, periodic solids, and those that treat materials as discrete molecules. Each approach has features and benefits; both have been widely employed to understand the emergent chemistry that arises from the formation of the metal-organic interface. This Review canvases these approaches to date, with emphasis placed on the application of electronic structure theory to explore reactivity and electron transfer using periodic, molecular, and embedded models. This includes (i) computational chemistry considerations such as how functional, k-grid, and other model variables are selected to enable insights into MOF properties, (ii) extended solid models that treat MOFs as materials rather than molecules, (iii) the mechanics of cluster extraction and subsequent chemistry enabled by these molecular models, (iv) catalytic studies using both solids and clusters thereof, and (v) embedded, mixed-method approaches, which simulate a fraction of the material using one level of theory and the remainder of the material using another dissimilar theoretical implementation.

129 citations

Journal ArticleDOI
TL;DR: The results indicate the important role of charge transfer for the N-O bond breaking in N2O and some relationships between the activation energy and orbital properties like HOMO energies and the spin densities of the metals at the active sites of the MOFs.
Abstract: The oxidation of CO by N2O over metal–organic framework (MOF) M3(btc)2 (M = Fe, Cr, Co, Ni, Cu, and Zn) catalysts that contain coordinatively unsaturated sites has been investigated by means of density functional theory calculations. The reaction proceeds in two steps. First, the N–O bond of N2O is broken to form a metal oxo intermediate. Second, a CO molecule reacts with the oxygen atom of the metal oxo site, forming one C–O bond of CO2. The first step is a rate-determining step for both Cu3(btc)2 and Fe3(btc)2, where it requires the highest activation energy (67.3 and 19.6 kcal/mol, respectively). The lower value for the iron compound compared to the copper one can be explained by the larger amount of electron density transferred from the catalytic site to the antibonding of N2O molecules. This, in turn, is due to the smaller gap between the highest occupied molecular orbital (HOMO) of the MOF and the lowest unoccupied molecular orbital (LUMO) of N2O for Fe3(btc)2 compared to Cu3(btc)2. The results ind...

66 citations

Journal ArticleDOI
TL;DR: The ability to rapidly distinguish promising MOFs from those that are "thermodynamic dead-ends" will be helpful in guiding synthesis efforts towards promising compounds.
Abstract: Metal-organic frameworks (MOFs) have emerged as promising materials for carbon capture applications due to their high CO2 capacities and tunable properties. Amongst the many possible MOFs, metal-substituted compounds based on M-DOBDC and M-HKUST-1 have demonstrated amongst the highest CO2 capacities at the low pressures typical of flue gasses. Here we explore the possibility for additional performance tuning of these compounds by computationally screening 36 metal-substituted variants (M = Be, Mg, Ca, Sr, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, W, Sn, and Pb) with respect to their CO2 adsorption enthalpy, $\Delta$H (T=300K). Supercell calculations based on van der Waals density functional theory (vdW-DF) yield enthalpies in good agreement with experimental measurements, out-performing semi-empirical (DFT-D2) and conventional (LDA and GGA) functionals. Our screening identifies 13 compounds having $\Delta$H values within the targeted thermodynamic window 40 $\leq$ $\Delta$H $\leq$ 75 kJ/mol: 8 are based on M-DODBC (M=Mg, Ca, Sr, Sc, Ti, V, Mo, and W), and 5 on M-HKUST-1 (M= Be, Mg, Ca, Sr and Sc). Variations in the electronic structure and the geometry of the structural building unit are examined and used to rationalize trends in CO2 affinity. In particular, the partial charge on the coordinatively unsaturated metal sites is found to correlate with $\Delta$H, suggesting that this property may be used as a simple performance descriptor. The ability to rapidly distinguish promising MOFs from those that are "thermodynamic dead-ends" will be helpful in guiding synthesis efforts towards promising compounds.

57 citations

Journal ArticleDOI
TL;DR: In this paper, the asymmetric supercapacitor (ASC) was fabricated using NiCo-(PTA)0.8(BTC) 0.2 nanosheets and reduced graphene oxide (rGO) as the positive and negative electrodes.

53 citations

Journal ArticleDOI
TL;DR: In this paper , the asymmetric supercapacitor (ASC) was fabricated using NiCo-(PTA)0.8(BTC) 0.2 nanosheets and reduced graphene oxide (rGO) as the positive and negative electrodes.

53 citations