Equilibrium Crystal Shape
The equilibrium shape of a crystal or nanoparticle minimizes its total surface free energy at fixed volume, which the Wulff construction gives from the surface energies of the individual facets (neglecting edge and corner effects). Because adsorption lowers facet surface energies by different amounts, the reaction environment can change particle shape and therefore the distribution of exposed active sites.
Sulfur-dependent shape of Cu particles (2009)
Using facet surface energies from atomistic thermodynamics and the WINXMORPH program, İnoğlu and Kitchin predicted Cu particle shapes as a function of the S chemical potential under WGS conditions (INOGLU 2009). The shape changes from one dominated by (111) and (100) facets at very low S chemical potential to one dominated by (110) at high S chemical potential, implying that the number and type of active sites depend on the reactive environment. Summary: inoglu2009.