Mechanochemical three-dimensional dynamic shearing for low-carbon scalable synthesis of nanoscale ductile metals

Scalable synthesis of ductile nanoscale metals is pivotal for modern industry, strongly depending on energy-intensive manufacturing processes and extensive use of chemical agents along with pronounced carbon fingerprints. Herein, we introduce a mechanochemical three-dimensional dynamic shearing approach that reduces the mean particle size of conventional ductile metals (Al, Fe, Cu, and Zn) from tens of micrometers to below 500 nm. Central to this approach is the use of silicic acid (H 2 SiO 3 ), which, with its moderate Mohs hardness and irregular, sharp structure, exerts intense vertical local shear forces on compressed metal sheets, thereby overcoming the spatial limitations of quasi-two-dimensional uniform mechanical surface load and effectively fragmenting ductile metals into nanoparticles. Simultaneously, H 2 SiO 3 can form a protective silica gel layer for in situ stabilization of the nanoparticles. As a proof-of-concept, we establish large-scale production of nanoscale Fe with over 70% Fe 0 content at a low cost of $3730 per ton, offering excellent storage stability and enhanced heavy metal removal performances for environmental remediation. Life cycle assessments reveal that this dynamic shearing approach reduces environmental impacts by 70%–88% and decreases carbon emissions by 62%–78% compared to conventional liquid or gas-phase reduction methods, advancing sustainable manufacturing practices in the realm of nanotechnology.