First-principles identification of CO oxidation via LH mechanism over ER mechanism on metal-boron centered single-metal dual site catalyst

Abstract

CO production has grown throughout time because of unwanted chemical reactions; therefore, the design of efficient and stable catalysts with minimal metal loading is in demand in the automobile industry for CO oxidation. Herein, density functional theory is used to study the CO oxidation mechanism on single-atom catalysts (SACs) and metal-boron centered single metal dual site catalysts (SM-DSCs). It is observed that CO oxidation could follow Eley-Rideal (ER) mechanism on single-atom catalysts, such as MN4, MN3, MN2, and MN2op systems, where M is a 3d transition metal. Whereas in the case of SM-DSCs, the inclusion of Boron will make the Langmuir-Hinshelwood (LH) mechanism possible over ER mechanism with less chance of CO poisoning. The Brønsted−Evans−Polanyi (BEP) relations are proposed (as a function of oxygen atom binding) to identify the energy barriers (Ea1 and Ea2) for the release of the first and second CO2 and O2 adsorption energies for any new SM-DSCs system. Further microkinetic model is implemented on 30 SM-DSCs and found that PtBN2op and AgBN2 SM-DSCs own best catalytic activity with high Sabatier activity and Turnover frequency for CO2 production. Hence, this work provides an approach toward the possibility of LH mechanism in the class of single-metal atom-based catalysts.