A density functional theory study on adsorption of SiHCl3-BCl3 by model molecules of g-C3N4

The removal of BCl3 from SiHCl3 is essential for the production of electronic grade polysilicon by Siemens method. In this paper, the adsorption configurations, electronic properties of g-C3N4 model molecules along with free and adsorbed BCl3/SiHCl3 are investigated by density functional theory (DFT) calculations, and their interaction mechanisms are analyzed so as to develop adsorbents with high efficiency and recyclability. The results showed that g-C3N4 interacted weakly with SiHCl3 molecules and adsorbed strongly for BCl3 with large adsorption energy and high charge transfer. Considering the recycling of the adsorbent, the desorption behavior of g-C3N4 on BCl3 was investigated by increasing the temperature and lowering the pressure by vacuuming, and it was found that reducing pressure consumed less energy than elevating temperature. It was further verified that g-C3N4 is suitable to be utilized as recyclable adsorbent.