Cu-Si bond and Cl defect synergistical catalysis for SiCl4 dissociation on CuCl2(1 0 0): A DFT study

Abstract

It is essential to convert SiCl4 into SiHCl3 over effective catalysts so as to construct a close-cycle sustainable polysilicon production process. However, the dissociation mechanism of SiCl4 is elusive yet. Here we adopted density functional theory (DFT) calculation to study the dissociation pathway of SiCl4, taking into account the effect of possible Cu-Si bond as well as the existing Cl defects in CuCl2 (100) surface. The first time we disclose that Cu-Si bond and Cl defect can synergistically catalyze the dissociation of SiCl4 into SiHCl3, with the activity superior to either individual Cu-Si bond or Cl defect. The calculation results reflect that on the Si/CuCl2(100)-Ⅰ surface, SiCl4 dissociation is inhibited, due to the lack of Cu-Si bond and low coordination Cu active sites; while the Si/CuCl2(100)-Ⅱ surface shows better catalytic activity towards SiHCl3 formation, comparing with different Cl-defect CuCl2(100) surfaces. Microkinetic modeling indicates that the formation rate of SiHCl3 depends on the intermediate SiCl3, and the most favorable pathway to generate SiHCl3 is through SiCl4 → SiCl3 + Cl(+H) → SiHCl3. This work can provide useful guidance on the rational design and synthesis of Cu-based catalysts for the dissociation of SiCl4 into SiHCl3 in the polysilicon production.