Dual transition metal doped germanium clusters for catalysis of CO oxidation

Abstract

CO oxidation is a crucial reaction to combat environmental pollution caused by fossil fuel burning, industrial exhaust and vehicle emissions. Searching for efficient catalysts made of economical and earth-abundant elements is vital and remains challenging. Here, we show for the first time that dual transition metal doped germanium clusters M2Ge12 (M = Cr, Mn, Fe, Co and Ni), which are experimentally accessible, are promising catalysts for low-temperature CO oxidation. Our first-principles calculations demonstrate that the reaction barrier has a linear relation with the O2 binding strength on the cluster, with the Ni2Ge12 cluster possessing the lowest barrier of 0.35 eV under the Eley-Rideal mechanism. The binding capability and activity are correlated to the d orbital center of two metal dopants in the cluster. Moreover, these M2Ge12 alloy clusters remain stable during the entire reaction process and exhibit satisfactory thermal stability and resistance to segregation. These theoretical results not only extend the application area of germanium-based alloy clusters, but also provide useful guidelines for designing inexpensive catalysts for CO oxidation and tuning their performance by electronic structure engineering.