CO 2 adsorption on the (111) surface of fcc-structure high entropy alloys

Abstract

High entropy alloys (HEAs), obtained by alloying five or more elements, can exhibit unique characteristics. The CO2 adsorption capabilities of fcc structure HEAs consisting of five elements among Fe, Co, Ni, Cu, Zn, Ru, Rh, Pd, Ag, Ir, Pt, and Au were evaluated by conducting first-principles calculations of the CO2 adsorption energy. HEAs could be categorized into “binding”, “less binding”, and “inconclusive” HEAs, where there were 27, 23, and 10 HEAs each, respectively, out of 60 randomly chosen HEAs. “binding” HEAs are defined as having low CO2 adsorption energy sites of less than -0.08 eV, which is difficult to attain with elementary substances or binary alloys. These low adsorption energy, or more active, sites are found near on-top positions of the HEA surface, whereas CO2 does not adsorb at such positions in “less binding” HEAs. Calculating CO2 adsorption energies could be a useful tool to check whether a specific HEA is “binding” or “less binding” prior to conducting extensive experiments.