Alloys are an important class of materials that often exhibit unique physical and chemical characteristics, such as exceptional hardness or enhanced chemical reactivity. As such, alloys show promise for many applications including heterogeneous catalysis and electro-catalysis. While the potential for the utilization of alloys in heterogeneous catalysis and electro-catalysis is significant, predictive models relating the geometric structure of alloys to the chemical reactivity are lacking.
We have used X-ray absorption spectroscopy (XAS) and quantum chemical density functional theory (DFT) calculations to identify critical features of the electronic structure of different sites in alloys that govern the local chemical reactivity. The measurements led to a simple model relating local geometric features of a site in an alloy to its electronic structure and chemical reactivity. The central feature of the model is that the formation of alloys does not lead to significant charge transfer between the constituent metal elements in the alloys, and that the local electronic structure and chemical reactivity can be predicted based on physical characteristics of constituent metal elements in their unalloyed form.