Engineering the Surface Architecture of Highly Dilute Alloys: An ab Initio Monte Carlo Approach

Citations Over TimeTop 12% of 2019 papers

Abstract

Highly dilute alloys of platinum group metals (PGMs: Pt, Rh, Ir, Pd, and Ni) with coinage metals (Cu, Au, and Ag) serve as highly selective and coke-resistant catalysts in a number of applications. The catalytic behavior of these materials is governed by the size and shape of the surface “ensembles” of PGM atoms. Therefore, establishing a means of control over the topological architecture of highly dilute alloy surfaces is crucial to optimizing their catalytic performance. In the present work, we use on-lattice Monte Carlo simulations that are parameterized by density functional theory-derived energetics to investigate the surface aggregation of PGM atoms under vacuum conditions and in the presence of CO. We study several highly dilute alloy surfaces at various PGM loadings, including Pd/Au(111), Pd/Ag(111), Pt/Cu(111), Rh/Cu(111), Ir/Ag(111), and Ni/Cu(111). Under vacuum conditions, we observe a thermodynamic preference for dispersion of PGM as single atoms in the surface of the coinage metal host, on all examined alloy surfaces except Ir/Ag(111), where Ir atom aggregation and island formation is preferred. By evaluating the alloy surface structure in the presence of CO, we determine that the size and shape of PGM ensembles can be manipulated by tuning the partial pressure of CO (PCO) on the Pd/Au(111), Pd/Ag(111), Ir/Ag(111), and Ni/Cu(111) surfaces. In contrast, we determine that Pt/Cu(111) and Rh/Cu(111) highly dilute alloys are unresponsive to changes in PCO with Rh and Pt dispersing as isolated single atoms within the host matrix, irrespective of gaseous composition. Our findings suggest that it may be possible to fine-tune the surface architecture of highly dilute binary alloys for optimized catalytic performance.

Related Papers

• → Thermoelectric properties of p-type LiZnSb: Assessment of ab initio calculations(2009)75 cited
• → Accurate line intensities for water transitions in the infrared: Comparison of theory and experiment(2017)50 cited
• → Reply Ab initio vibrational raman spectra of small ring molecules: Examples that warrant reevaluation of a scaling theme(1989)7 cited
• → Sustainable conversion of biomass oxygenates(2015)
• Ab Initio Studies of Chlorine Oxide and Nitrogen Oxide Species of Interest in Stratospheric Chemistry(1995)