Unpacking SiO 2 precursor effects on aluminothermic reduction in molten NaCl–KCl mixture to yield porous silicon
Year: 2026
Type: article
Abstract: Developing lower-energy routes to silicon-based materials is important for improving the sustainability of chemical processes. Porous silicon (p-Si) is a nontoxic material with applications in CO 2 reduction, photocatalytic water splitting, lithium-ion batteries, and on-demand hydrogen generation, yet conventional silicon production relies on energy-intensive carbothermal reduction of SiO 2 at >1500 °C. Aluminothermic reduction offers a lower-temperature alternative, but many reported methods rely on volatile AlCl 3 salt. Recently, we reported a molten-salt-assisted aluminothermic reduction of fumed SiO 2 using a NaCl-KCl mixture that produces p-Si within 2 h that can yield large quantities of hydrogen on-demand. Here, we evaluate the generality of this approach by applying it to additional SiO 2 precursors (−325 mesh and Stöber silica) and investigate the factors governing reduction efficiency. We find that the extent of reduction is strongly dependent on precursor surface area, with high-surface-area fumed SiO 2 undergoing the most complete conversion and Stöber precursor the least. Electron microscopy reveals substantial molten-salt-induced restructuring of SiO 2 , indicating that precursor morphology and surface area play key roles in controlling reduction kinetics. These results establish structure–reactivity relationships for molten-salt aluminothermic reduction and provide guidance for designing more efficient and scalable routes to porous silicon.
Source: Canadian Journal of Chemistry
Authors: Toren Hynes, Sarah A. Martell, Mita Dasog
Institution: Dalhousie University
Language: English
Subfield: Fluid Flow and Transfer Processes
Field: Chemical Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7212286180
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