Millisecond self-heating and quenching synthesis of Fe/carbon nanocomposite for superior reductive remediation

Fe0-based nanomaterials are extensively applied in environmental remediation, but their passivated oxide shell restricts deep application. However, efforts aimed at revitalizing Fe-oxide shells have shown limited success. Here, we report a "faster win fast" approach by preferential carbon layer deposition in milliseconds to block Fe-oxide shell growth via carbon-assisted flash Joule heating (C-FJH) reaction. C-FJH induced ultra-high temperature and electric shock promoted reductive Fe formation and subsequently melted to a phase-fusional heterostructure (Fe0/FeCl2). Therefore, theoretical calculation confirmed that electron delocalization effect of derived heterostructure promoted electron transfer. Synchronously, rapid self-heating/quenching rate (∼102 K/ms) realized a thin aromatic-carbon layer deposition to sustain both high stability and activity of reductive Fe. The channels of thin aromatic-carbon layer favored inward diffusion of pollutants, which facilitated the subsequent reduction. Accordingly, derived heterostructure and carbon layer jointly contributed to the boosted removal of multiple pollutants (including metal oxyanions, perfluorinated compounds, and disinfection by-products).