DFT study of composites formed by M2 metallic clusters (M = Ni, Cu, Fe and Au) embedded in faujasite

Abstract

The present work is a theoretical study of the different frameworks and composites of faujasite (FAU) zeolite. Most of the computations for composites were performed by embedding M₂ metal clusters (M = Ni, Cu, Fe and Au) within the Al₂Si₄₀O₉₆ FAU zeolite framework. Results showed that, in this framework, the difference between the α and β spin induced an unfolding band structure for Cu₂ and Au₂ clusters. Thus, their respective band gap energy decreased. In addition, low energy band gap values are associated with composites in which the cluster presents practically no hybridized orbitals. In particular, the charge trace of a zeolitic framework was identified as a fingerprint that is different for other types of zeolites and composites. In this charge trace, the framework atoms on equivalent sites with lower charge values were identified as being responsible for clusters adsorption.