We provide a mesoporous silicon material (PSi) prepared via a template-free and HF-free process. The production process is facile and scalable, and it may be conducted under mild reaction conditions. The silicon may be produced directly by the reduction of a silicon-halogenide precursor (for example, SiCl.sub.4) with an alkaline alloy (for example, NaK alloy). The resulting Si-salt matrix is then annealed for the pore formation and crystallite growth. Final product is obtained by removal of the salt by-products with water.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
 This invention was made with government support under Grant No. DE-AC02-05CH11231, awarded by the Department of Energy. The Government has certain rights in the invention.