Study on Room-Temperature Wet Oxidation of Silicon Catalyzed by Copper

Abstract

The anomalously fast growth of the silicon oxide layer at room temperature has been reported for the Cu/Si system. However, the systematical exploration of such a reaction under humidity conditions has not yet been carried out. Through one combination of the experiments and first-principle density functional theory (DFT) simulations, here, we investigate the influence of the imparted Cu atoms in Cu/Si on the oxidation of Si with the presence of H2O. The Cu addition causes the geometric distortion of the Si lattice, which alters the charge transfer to absorbed H2O and decreases its dissociation energy. This results in the experimental formation of much defective SiO x for the Cu/Si system than bare Si under humidity conditions. Furthermore, the presence of such an oxide structure and the catalytic effect of Cu provide the suitable diffusion channels and adsorption sites for the H2O transport and its dissociation. This enhances the oxidation rate of Si consequently and results in the fast growth of the oxide layer on Cu/Si at room temperature.

Anin situexsolved Cu-based electrocatalyst from an intermetallic Cu5Si compound for efficient CH4electrosynthesis

“…When the air-annealing temperature was raised to 400 °C, the annealed Cu 5 Si shows two small peaks at 2 θ = 43.1° and 46.2°, corresponding to the (002) and (101) planes of Cu 6.69 Si, respectively, indicating partial conversion of Cu 5 Si to Cu 6.69 Si either in the bulk or on the surface, which is probably a result of preferential exsolution of Si from the Cu 5 Si parent as the energy required to form Si oxides is much lower than that to form Cu oxides. 16 However, it is noted that no visible XRD peaks related to crystallized SiO 2 can be observed, suggesting that the exsolved Si oxides (SiO x ) most likely exist in an amorphous form that have been confirmed by surface-sensitive spectroscopic measurements ( vide infra ). Meanwhile, apart from this conversion, several characteristic XRD peaks at 50.2° and 73.6° for the metallic Cu and 35.5° and 38.7° for the CuO can be clearly observed for the Cu 5 Si during air-annealing.…”

Facile synthesis of Cu-based catalysts from Cu3Si and their catalysis properties study

“…2,3 Our prior research highlighted unique low-temperature oxidation behavior in Cu 3 Si@Si particles, which transition into CuO@SiO x , as well as rapid Cu diffusion within Si particles at room temperature. 4,5 Concurrently, interest has surged in Cu-Si composites and their related derivatives, especially Cu on silica supports, due to their active participation in a wide range of catalytic reactions like hydrogenation, carbonization, and oxidation. [6][7][8] Extensive efforts have been made to load copper species with controlled sizes and shapes, which significantly influence catalytic performance, onto supports.…”