First-Principles Design of Iron-Based Active Catalysts for Adsorption and Dehydrogenation of H₂O Molecule on Fe(111), W@Fe(111), and W₂@Fe(111) Surfaces

Abstract

The adsorption and dehydrogenation of water on Fe(111), W@Fe(111), and W2@Fe­(111) surfaces have been studied via employing the first-principles calculations method based on the density functional theory. The three adsorption sites of the aforesaid surfaces, such as top (T), 3-fold-shallow (S), and 3-fold-deep (D), were considered. The most favorable structure of all OH x (x = 0–2) species on the surfaces of Fe(111), W@Fe(111), and W2@Fe­(111) have been thoroughly predicted and discussed. Our calculated results revealed that the adsorbed configurations of FeH2O­(T-η1-O)-b, W@FeH2O­(T-η1-O)-a, and W2@FeH2O­(T-η1-O)-a possess energetically the most stable structure with their corresponding adsorption energies of −8.08, −13.37, and −18.61 kcal/mol, respectively. In addition, the calculated activation energies for the first dehydrogenation processes (HO-H bond scission) of H2O on Fe(111), W@Fe(111), and W2@Fe­(111) surfaces are 24.40, 12.62, and 9.97 kcal/mol, respectively. For second dehydrogenation processes (O–H bond scission), the corresponding activation energies of OH on Fe(111), W@Fe(111), and W2@Fe­(111) surfaces are 39.35, 22.69, and 26.24 kcal/mol, respectively. Finally, the entire dehydrogenation courses on the varied Fe(111), W@Fe(111), and W2@Fe­(111) surfaces are exothermic by 20.08, 41.35, and 59.30 kcal/mol, respectively. To comprehend the electronic properties of its nature of interaction between the adsorbate and substrate, we calculated the electron localization functions, local density of states, and Bader charges; the results were consistent and explicable.

Water Adsorption and Dissociation on Copper/Nickel Bimetallic Surface Alloys: Effect of Surface Temperature on Reactivity

“…It is worth noting that within the same system the surface alloys with 2 Cu atoms and 2 Ni atoms either on Cu(111) or Ni(111) showed lower barrier compared to other surface compositions (except for Ni4_Cu(111)). Similar observations were also reported for H 2 O dissociation on Pd−Cu(100) 38 and W− Fe(111) 39 bimetallic surface alloys where in the surface compositions Pd2_Cu(100) and W2_Fe(111) surfaces showed lower barrier. These results indicate that the presence of 50% composition of each alloying element in a bimetallic surface alloys lead to decrease in activation energy for reaction.…”

“…Among the five surface alloys with varying concentration of Pd (Pd x –Cu 4‑x ; x = 0–4), Pd 2 –Cu 2 (100) surface with two surface Pd atoms was found to be kinetically and thermodynamically optimal for H 2 O dissociation . Similarly, Fe(111) surface with a barrier of 1.05 eV for H 2 O dissociation showed a decrease in the activation barrier heights to 0.55 and 0.43 eV, respectively, for surface alloys obtained by replacement of 1 and 2 surface atoms by W thereby highlighting the advantages of using surface alloys in catalysis …”

“…38 Similarly, Fe(111) surface with a barrier of 1.05 eV for H 2 O dissociation showed a decrease in the activation barrier heights to 0.55 and 0.43 eV, respectively, for surface alloys obtained by replacement of 1 and 2 surface atoms by W thereby highlighting the advantages of using surface alloys in catalysis. 39 The aim of this work is to understand the rate-determining water adsorption and dissociation step of WGS reaction on bimetallic close-packed surface alloys of Cu and Ni and pin down the reactivity change to one or more electronic effects. In addition, we study in detail the effect of surface temperature on reactivity using the parameters calculated from density functional theory (DFT) and compare them with the results from rigid surface calculations.…”

Theoretical Insights into the Structure, Stability, Electronic, and Photocatalytic Properties of BaNbO2N Low-Index Surfaces

“…A remarkable transfer of charge between the adsorbate and substrate will play an important role in accelerating the catalytic process. 56 3.7. Mechanisms of OER on BaNbO 2 N Surfaces.…”

“…For a given surface, the amount of charge transfer between Ba-termination and water is larger than that between Nb-termination and water. A remarkable transfer of charge between the adsorbate and substrate will play an important role in accelerating the catalytic process …”