Preparation of porous silicon by vacuum sublimation dealloying method

Abstract

Porous silicon has many potential applications in lithium-ion battery anodes and medical sensors, owing to its high specific capacity and photoluminescence properties. In this work, porous silicon is prepared with vacuum sublimation dealloying method by heating Mg2Si precursor to 750 °C and holding it for 1 h under vacuum. The relationship between pressure and temperature, as well as the characteristics of the longitudinal section of condensation products show that the sublimation process of Mg in Mg2Si precursor can be divided into three stages. The aperture distribution curves of the Brunauer-Emmett-Teller (BET) and Mercury Intrusion Porosimetry (MIP) of porous silicon show that the pore size of mesopores is between 3.1 ± 0.2 and 6.3 ± 0.2 nm, and that of macropores is between 351.6 ± 1 and 2101.7 ± 1 nm. The prepared porous silicon has pores with frost flower shaped and shrub-shaped structures in the interior and polygonal contoured pores on the surface. This paper aims to investigate the reaction mechanism of vacuum sublimation dealloying method and provide a foundation for optimizing the performance of porous silicon in applications such as lithium-ion battery anodes and hydrogen generating materials by studying its unique pore structure.