Effects of ensembles, ligand, and strain on adsorbate binding to alloy surfaces

Abstract

Alloying elements with strong and weak adsorption properties can produce a catalyst with optimally tuned adsorbate binding. A full understanding of this alloying effect, however, is not well-established. Here, we use density functional theory to study the ensemble, ligand, and strain effects of closepacked surfaces alloyed by transition metals with a combination of strong and weak adsorption of H and O. Specifically, we consider PdAu, RhAu, and PtAu bimetallics as ordered and randomly alloyed (111) surfaces, as well as randomly alloyed 140-atom clusters. In these alloys, Au is the weak-binding component and Pd, Rh, and Pt are characteristic strong-binding metals. In order to separate the different effects of alloying on binding, we calculate the tunability of Hand O-binding energies as a function of lattice constant (strain effect), number of alloy-substituted sublayers (ligand effect), and randomly alloyed geometries (ensemble effect). We find that on these alloyed surfaces, the ensemble effect more significantly tunes the adsorbate binding as compared to the ligand and strain effects, with the binding energies predominantly determined by the local adsorption environment provided by the specific triatomic ensemble on the (111) surface. However, we also find that tuning of adsorbate binding from the ligand and strain effects cannot be neglected in a quantitative description. Extending our studies to other bimetallics (PdAg, RhAg, PtAg, PdCu, RhCu, and PtCu), we find similar conclusions that the tunability of adsorbate binding on random alloys is predominately described by the ensemble effect.

Sulfur Loading and Speciation Control the Hydrophobicity, Electron Transfer, Reactivity, and Selectivity of Sulfidized Nanoscale Zerovalent Iron

“…This unique site‐evolution phenomenon can be attributed to the ensemble effect that causes H to migrate from an inert element to a highly active element in an alloyed surface ensemble. [ 58 ] More importantly, our theoretical studies here demonstrate the hydrophobic nature of sulfur irrespective of how sulfur combines with Fe. Additional information about the computational results and methods can be found in the Supporting Information.…”

Tuning the Catalytic Preference of Ruthenium Catalysts for Nitrogen Reduction by Atomic Dispersion

“…Figure 4c shows that HER on Ru(0001) is ≈0.19 eV more facile than on Ru SAs/g-C 3 N 4 for the hydrogen evolution, indicating that HER is relatively difficult on under-coordinated surface sites due to the strong binding of H. Also, the adsorption free energy of H is more exothermic than that of N 2 at Ru(0001) (Figure 4b), while these two binding energies at Ru SAs/g-C 3 N 4 are similar. [31] As discussed, both the H and N 2 binding energies are tuned stronger for the systems with single-atom Ru. Since our experiments were under alkaline conditions, we also evaluated the kinetic barrier of the water dissociation step, as shown in the inset of Figure 4c.…”

“…It should be noted that the tunability of adsorbate bindings is particularly important for tuning the activity of a specific catalytic site. [31] As discussed, both the H and N 2 binding energies are tuned stronger for the systems with single-atom Ru. For bulk Ru, the activity is dominated by nondefected Ru sites (e.g., the energetically favorable (0001) surface) which promotes HER and inhibits NRR.…”

Design, Modeling, and Experiments of the Vortex‐Induced Vibration Piezoelectric Energy Harvester with Bionic Attachments

“…Energy policy has become a key strategy in the recent decades in the world [1], and researches focus on energy has been extended in many fields, e.g., environmental protection [2][3][4], industrial catalysis [5][6][7], and energy storage [8][9][10][11][12][13]. Additionally, in recent years, under the background of big data technology [14,15], some new types of low-power consumption technologies like MEMs and WSNs [16,17] have been introduced into many areas.…”