Selectivity of Ni-based surface alloys toward hydrazine adsorption: A DFT study with van der Waals interactions

Hydrogen Production via Hydrazine Decomposition on Model Platinum–Nickel Nanocatalyst with a Single (111) Facet

“…Possible reaction mechanisms were proposed for the catalytic hydrazine decomposition in previous studies. − It is generally believed that the reaction on metal surfaces initiates from adsorption of hydrazine molecules, which then dehydrogenate by breaking the N–H bonds and generate N 2 H x (1 ≤ x ≤ 3) intermediates and adsorbed hydrogen species. A complete dehydrogenation of the N 2 H x intermediates and recombination between adsorbed hydrogen atoms lead to the generation of final products, N 2 and H 2 .…”

Understanding of Selective H2 Generation from Hydrazine Decomposition on Ni(111) Surface

“…First-principles calculations were performed using the Vienna ab initio Simulation Package with projected-augmented-wave pseudopotentials. , Spin-polarized generalized gradient approximation of Perdew–Burke–Ernzerhof exchange-correlation functional was used with a plane wave cutoff energy of 400 eV, which is sufficient to ensure the convergence. − The lattice constant of nickel bulk was optimized to 3.53 Å, consistent with the experimental value (3.52 Å) . Ni(111) surface was modeled by a five-layer periodic slab with a vacuum thickness of 20 Å.…”

“…The integration of the Brillouin zone was done with Gamma-centered 5 × 5 × 1 and 7 × 7 × 1 k -point grid for the 3 × 3 and 2 × 2 supercell, respectively. The van der Waals interaction is not expected to affect the properties because strong chemical bonds are formed between the adsorbates and the surface, as suggested in ref . The minimum energy paths (MEPs) and transition states (TSs) were determined by the climbing-image nudged elastic band method .…”

“…A series of Ni-based bimetallic catalysts, like Ni–Ir and Ni–Pt, enabled complete decomposition of N 2 H 4 ·H 2 O at moderate temperatures with nearly 100% H 2 selectivity. ,− But in spite of this encouraging experimental progress, the mechanistic study of catalytic decomposition of N 2 H 4 over Ni-based catalyst is still in its infancy. So far, there exist only preliminary theoretical studies exploring N 2 H 4 adsorption on Ni , and Ni-based alloy surfaces, while a detailed catalytic mechanism of N 2 H 4 decomposition is still absent. Such lack of mechanistic insight into the catalytic decomposition process will inevitably hamper the experimental exploration of high-performance N 2 H 4 decomposition catalysts.…”

Size Sensitivity of Supported Palladium Species on Layered Double Hydroxides for the Electro-oxidation Dehydrogenation of Hydrazine: From Nanoparticles to Nanoclusters and Single Atoms

“…The calculated order of d-band centers was Pd SAs/NiFe (2.25 eV) < Pd NPs/NiFe (2.18 eV) < Pd NCs/NiFe (1.76 eV), which was in an inverted sequence of the adsorption energy of N 2 H 4 . This can be due to the fact that higher d-band centers can form higher antibonding orbitals through metal–N interactions, leading to more electrons in the bonding orbital. , The calculations of the free energy of each dehydrogenation step were conducted on the Pd catalysts (Figures c,d and S18). By comparing the adsorption configuration and the length of the Pd–N bond on three catalysts (Figure S19), it can be found that the N 2 H 4 on Pd NPs/NiFe with a Pd–N bond of 3.2 Å did not present the most stable centrosymmetric configuration, which may be caused by the large steric hindrance of planar Pd NPs/NiFe.…”