Structure Sensitive Reaction Kinetics of Chiral Molecules on Intrinsically Chiral Surfaces.

Enantiospecific heterogeneous catalysis utilizes chiral surfaces to resolve enantiomers via structure sensitive surface chemistry. The catalyst design challenge is the identification of chiral surface structures that maximize enantiospecificity. Herein, we develop data driven models for the enantiospecificity of tartaric acid reactions on chiral Cu() surfaces.

H-D Exchange Activity and Electronic Structure of Ag Pd Alloy Catalysts Spanning Composition Space.

Many computational studies of catalytic surface reaction kinetics have demonstrated the existence of linear scaling relationships between physical descriptors of catalysts and reaction barriers on their surfaces. In this work, the relationship between catalyst activity, electronic structure, and alloy composition was investigated experimentally using a Ag Pd Composition Spread Alloy Film (CSAF) and a multichannel reactor array that allows measurement of steady-state reaction kinetics at 100 alloy compositions simultaneously. Steady-state H-D exchange kinetics were measured at atmospheric pressure on Ag Pd catalysts over a temperature range of 333-593 K and a range of inlet H and D partial pressures.

Atomic-scale origin of the enantiospecific decomposition of tartaric acid on chiral copper surfaces.

The origin of the enantiospecific decomposition of L- and D-tartaric acid on chiral Cu surfaces is elucidated on a structure-spread domed Cu(110) crystal by spatially resolved XPS and atomic-scale STM imaging. Extensive enantiospecific surface restructuring leads to the formation of surfaces vicinal to Cu(14,17,2) which are responsible for the enantiospecificity.

Surface Segregation Studies in Ternary Noble Metal Alloys: Comparing DFT and Machine Learning with Experimental Data.

Surface segregation, whereby the surface composition of an alloy differs systematically from the bulk, has historically been hard to study, because it requires experimental and modeling methods that span alloy composition space. In this work, we study surface segregation in catalytically relevant noble and platinum-group metal alloys with a focus on three ternary systems: AgAuCu, AuCuPd, and CuPdPt. We develop a data set of 2478 fcc slabs with those compositions including all three low-index crystallographic orientations relaxed with Density Functional Theory using the PBEsol functional with D3 dispersion corrections.

Activation by O of AgPd Alloy Catalysts for Ethylene Hydrogenation.

A composition spread alloy film (CSAF) spanning all of AgPd composition space, = 0 → 1, was used to study catalytic ethylene hydrogenation with and without the presence of O in the feed gas. High-throughput measurements of the ethylene hydrogenation activity of AgPd alloys were performed at 100 Pd compositions spanning = 0 → 1. The extent of ethylene hydrogenation was measured versus at reaction temperatures spanning = 300 → 405 K and inlet hydrogen partial pressures spanning = 70 → 690 Torr.