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Using a sequential molecular dynamics (MD)/time-stamped force-bias Monte Carlo (tfMC) algorithm to simulate the deposition of Cu species onto a TiN(001) substrate at 600 K, it is shown for the first time that at the very early stage of growth, BCC-Cu grows pseudomorphically on the TiN(001) substrate as a very thin continuous film with the BCC-Cu[001]//TiN[001] growth direction. By increasing the thickness of the Cu thin film, however, the film transforms through the Nishiyama-Wasserman mechanism from BCC into predominantly FCC-Cu with abundant nanotwins, which is the same type of structure obtained in the experiment conducted here via a dc magnetron sputter deposition technique to grow Cu on TiN(001) at 105 °C. In agreement with the experimental observations in the literature, the devised MD/tfMC is employed further to reveal that on the N-terminated TiN(111), Cu shows a very poor wettability, and FCC-Cu(111) grows vertically in the form of tall 3D islands. On Ti-terminated TiN(111) surface, however, FCC-Cu(111) initially grows in the form of 2D islands with high wettability. With additional Cu deposition, a triangular misfit dislocation network is generated at the Cu(111)//Ti-terminated TiN(111) interface with subsequent formation of a two-layer nanotwin with its twinning plane parallel to the surface substrate.

Defect and substrate introduced into catalyst are two feasible routes toward design of heterogeneous catalysts. It is vital to identify and understand the relationships among atomic, electronic structures and adsorbate binding ability of the catalytic surfaces. Herein, hydrogen evolution on different defect graphene with and without two-dimensional (2D) Mo2C substrate are selected as examples to explore the relationships. Three feasible electronic structural descriptors, including p and pz band centers of local atoms, electron transfer to local atoms, and deformation charge densities of composite structures, are exacted from electronic properties of the defect and substrate-supported graphene. It is found that those descriptors could predict the hydrogen binding energy quantitatively, and the hydrogen adsorption order qualitatively. The descriptor of local p and pz band centers originate from hybridization between the site atom and adsorbate. It is believed that the relationship of atomic structure, electronic structure and binding energy may be applied to other surfaces, and shed light on the nature origin of the structure–activity on electrochemistry. By tuning the descriptors by atomic structure of defect or substrate, suitable hydrogen binding ability and superior hydrogen evolution performance of graphene could be achieved. Several structures based on graphene own superior hydrogen evolution activity: the exchange current densities of S3NV1-G, S2NV2-G@Mo2C, N1-G@Mo2C, and N2-G@Mo2C are predicted to be 0.811, 0.963, 0.712, and 1.860 mA/cm2, respectively. Especially the last two ones, their negative interfacial binding energies, and the energy favorability of forming N1 and N2 defects, ensure their stabilities and easy syntheses in experiment, and enhance their potential applications.

First principles density functional theory calculations were used to explore the enhancement of the structural integrity of Cu/TiN metal/ceramic interfaces by substitutional doping of the interface with Ni, Zn and Sn. To evaluate the interfacial strength, energy barriers to shear displacement and maximum tensile stress before fracture were calculated. Enthalpy of mixing dictated that Sn was not energetically suitable for doping at the interface, whereas both Ni and Zn were. Ni segregated at the interface forming sub-nanometer interlayers between Cu and TiN, whereas Zn formed a solid solution with Cu. While Zn-doping increased the resistance to shear, it led to a weakening of tensile strength. Ni interlayers increased both the shear and tensile strength to a significant degree coinciding with an increase in electron density between the layers. Using analysis form their partial density of states, Ni interlayers were found to accept more electrons from interfacial Ti into their more compact 3d-orbitals than Cu, which accepted more into available 4s-orbitals. Zn doping increased resistance to shear due to its lower electronegativity than Cu, causing interfacial Zn to have a more positive charge, which also raised the barrier to shear when in close contact with positively charged interfacial Ti atoms.