The effect of chlorine vacancy in CuCl2 (0 0 1) catalyst on the mechanism of SiCl4 dissociation into SiHCl3: A DFT study

Abstract

In order to elucidate the role of chlorine vacancy on CuCl2 catalyst in species adsorption and the mechanism of SiCl4 dissociation into SiHCl3, density functional theory (DFT) calculations were performed over the CuCl2(0 0 1) surfaces with single and double Cl-vacancy, comparing with those over the perfect CuCl2(0 0 1). The calculation results show that Cl vacancies on the CuCl2(0 0 1) surface cause low-coordination site Cu atoms and the exposed Cu atoms work as the actually catalytic active sites, which can promote species adsorption and dissociation. The CuCl2 catalyst enriched with exposed Cu active sites exhibits higher catalytic activity and higher selectivity of SiHCl3. Bader charge analysis indicates that the smaller positive charge leads to the higher species adsorption energies and better catalytic selectivity and activity of SiCl4 dissociation into SiHCl3. The closer the d-band center is to the Fermi level, the higher the species adsorption energy and the better catalytic selectivity and activity of SiCl4 dissociation into SiHCl3. It suggests that the double Cl-vacancy CuCl2(0 0 1) catalyst has better activity and selectivity to produce SiHCl3 via SiCl4 decomposition, and the favorable pathway is SiCl4 → SiCl3 + Cl+(H) → SiHCl3, which can provide useful guidance on the development of efficient catalysts for SiCl4 dissociation into SiHCl3.