Strong Metal–Support Interactions of TiN– and TiO₂–Nickel Nanocomposite Catalysts

Abstract

This study investigates the electronic configuration of titanium nitride-nickel (TiN−Ni) nanocomposites, in order to explain the high stability and activity of this hydrogenolysis catalyst. TiN−Ni is compared to a titanium oxide-nickel reference (TiO 2 −Ni). Strong metal−support interactions are observed between the TiN and Ni. Scanning transmission electron microscopy (STEM) and energy-dispersive X-ray spectroscopy (EDS) illustrate that the Ni distributes more homogeneously on the nitride support. Computational comparison of TiN−Ni and TiO 2 −Ni provides evidence of preferential Ni adsorption onto nitrogen sites of the nitride support. DFT calculations also predict a charge polarization between Ti and Ni atoms. X-ray photoelectron spectroscopy (XPS) corroborates computational analysis by revealing a suppression of surface nitride species upon deposition of Ni onto TiN. Shifts in Ti 2p and Ni 2p binding energy positions are also evident, which indicate an electronic perturbation between TiN and Ni. We conclude that the presence of nitrogen in the nitride support influences the electronic and structural properties of TiN−Ni and is partly responsible for the beneficial catalytic properties reported for this nanocomposite.

Confining sulfur in intact freestanding scaffold of yolk-shell nanofibers with high sulfur content for lithium-sulfur batteries

“…2 b, c), the Ti 2 p spectra of TiO 2 -CNFs@void@TiN@C show three types peaks, which is attributed to Ti-O bond (464.4 and 458 eV), Ti −N −O bond (462.9 and 457.2 eV) and main Ti −N bond (461.2 and 456 eV). Although there is a low content of O in Ti −N −O and Ti −O, the main ingredient of the outer layer is TiN phase, which is consistent with previously reported TiN-based materials [32][33][34][35] . In addition, the three peaks at 395.1, 397.3 and 399.2 eV of the N 1 s spectra can be assigned to the C −N, Ti −N, and Ti −N −O bond, respectively [36] .…”

An Operando X-ray Absorption Spectroscopy Study of a NiCu−TiO2 Photocatalyst for H2 Evolution

“…Additionally, oxygen is distributed over the entire NP surface (Figure j), but its signal seems to be more intense in the outermost ∼5 nm of the NP and at the Ni-rich zones. The presence of the outer thin oxide layer “wrapping” the Cu-rich zone, as mentioned above, may be explained by the exposure of the sample to ambient conditions, , whereas the oxygen distribution over the Ni-rich region can be ascribed to a strong interaction between Ni and TiO 2 during dewetting …”

“…The presence of the outer thin oxide layer "wrapping" the Cu-rich zone, as mentioned above, may be explained by sample exposure to ambient conditions, 50,51 whereas the oxygen distribution over the Ni-rich region can be ascribed to a strong interaction between Ni and TiO2 during dewetting. 62 Summing up, ex-situ XRD, XPS and EDS-TEM analysis evidence for the co-catalyst NPs the presence of oxidized surface Cu and Ni species with a metallic NP core. Moreover, the data apparently suggest that the content of metallic Cu and Ni relative to that of their oxides is higher after photocatalysis than in the as-formed samples.…”

Vibrational Analysis of Paraelectric–Ferroelectric Transition of LiNbO3: An Ab-Initio Quantum Mechanical Treatment

“…As shown by a previous paper, the combined use of the B3LYP functional and the triple ζ basis set [20][21][22][23][24][25][26] provides very accurate results for the vibrational spectra, in terms of both wavenumbers and intensities [25,[27][28][29][30][31]. The exchange and Coulomb infinite lattice series can be modified through five parameters, T i , which were set to 8 (T 1 -T 4 ) and 16 (T 5 ).…”