(6cx) Mechanical Work Makes Important Contributions to Surface Chemistry

Surface chemistry is thought to be controlled exclusively by electronic factors. In this work, we show that in addition to the established electronic factors a mechanical work term arises upon the application of stress (Nat Comm 6, 2015). This mechanical work term is due to the interaction of the applied stress field with the relaxation (strain field) induced by the presence of a bound molecule. The mechanical work term has dependencies different from established electronic parameters and allows for cases of stronger (weaker) binding upon the application of compression (tension), opposite to expectations from electronic parameters. It is shown explicitly for the case of methanation catalysis that stress induced chemistry changes may shift the activity of Ni to that of Ru and Co; an activity shift comparable to moving one element across the periodic table with compositional or structural changes. When designed in using core-shell particles a stress field may be used to tune the activity of a catalyst to hit peak activity precisely adding a new technique for catalyst design.