Elastic Effects in Adsorbate-Adsorbate Interactions of C and S on a Stepped Ru Surface

We examine strain modification of adsorbate adsorbate inter- action in the (C*+S*)/fcc-Ru(211) system for relevance to biomass to hydrocarbon catalysis and the broader case of interaction changes under strain. Applied biaxial strains from -3% to +3% shift the C and S binding and interaction energies by +/- 0.3 eV for C and +/- 0.1 eV for S, binding and interaction being additive and leading to stronger binding with tension, creating larger total changes in binding for the covered surfaces. Changes in the near-neighbor interactions with strain are found to be primarily electronic in origin there is little change in mechanical interaction. While mixing and thermodynamic analysis reveals that the C+S system will mix over the complete range of strains studied, the application of strain, whether tensile or compressive, may lead to reduced sulfur coverage. For biomass catalysis, the implication is that strain may be used to optimize hydrocarbon chemistry with only improvements in poisoning due to site blocking. It is argued that the serendipitous addition of binding and interaction may not be specific but a general case and, therefore, contribute to the utility of strain engineering.