Quantum Chemical Calculations. Silanol Reaction

Solar energy has a great significance and a wide application prospect due to the extensive sources, lowest cost of resources and no pollution to the environment.Preparation of the traditional method of solar-grade polysilicon has polluted the environment, expensive equipment, flow length, high energy consumption and high production costs.Important precondition of extensive application of photovoltaic technology was decreasing the energy consumption and the cost of production, and reducing environmental damage.Reducing reaction of silanol and strong reductant, such as hydrogen, carbon monoxide and sodium, were studied systematically. The B3LYP method is better by comparing the with HF method. Stable configurations, properties and bonding situation of SiH3OH, (CH3)3SiOH, C6H5(CH3)2Si0H, (CH3)2Si(OH)2, CH3Si(OH)3 were researched by GAUSSIAN03.E01 software and DFT/B3LYP/6-311G** on basis set level. Thermodynamic property of system of reducing reaction for five species silanol and five kinds of reducing agents were calculated to screening the reaction systems.All of five species silanol have low symmetry properties. SiH3OH has the highest molecular energy.(CH3)2Si(OH)2 had the best polarity.Oxygen atoms and carbon atoms had a great influence on chemical activities of molecules by analysis of frontier molecular orbital. The analysis results of overlap population and stabilization energy showed that Si-C bond, O-H bond, Si-O bond, and Si-H bond were liable to chemical reaction due to easier to fracture.Carbon was selected as the first of reducing agents for reducing reaction of silanol because of the best reducibility. At the same time the△G<0 on the thermodynamics of the system was screened as the possible step in next study.Promotive effect to understanding the characteristics of silanol reducing reaction and riching the theory of silicon purification. New ways for preparation of high purity silica could be explored.