Magnesiothermic reduction can directly convert SiO2 into Si nanostructures. Despite intense efforts, scalable fabrication of highly nanoporous silicon by Mg still remains a significant challenge due to the exothermic reaction nature. By employing ionic compounds as a heat scavenger for the magnesiothemic reduction, we demonstrate an efficient and scalable route to convert diatom (SiO2) and SiO2/GeO2 into nanoporous Si and Si/Ge composite, respectively. Fusion of a heat scavenger during the reaction consumes a large amount of heat that otherwise collapses the nano-porosity of products and agglomerates silicon domains into large crystals. Our methodology is potentially competitive for a large scale production of nanoporous Si and Si/Ge composite with a low cost, which can have a strong impact on various applications including thermoelectrics, lithium-ion batteries and sensors.

Scalable fabrication of nanoporous Si and Si/Ge enabled by a heat scavenger in magnesiothermic reactions

246th National Meeting (2013)

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