1. Interface design of iron nanoparticles and applications in environmental remediation

2. (A) Liquid nitrogen activation of ZVI^[50], (B) HRTEM images showing three types of Fe nanoparticles with core-shell structure^[51], (C) sodium borohydride being introduced to reduce Fe³⁺ to ZVI^[52], (D) illustration of the [LiBipy]-driven two-step synthesis: formation of [LiBipy] radical by coupling reaction^[55]

3. (A-a) Schematic illustration of the small iron nanoparticles in a capsule (Fe/C@mSiO₂)^[58], (A-b) schematic illustration of the Sol-Gel coating process and in-situ confined thermally reduction strategy for the fabrication of the porous carbon capsulated Fe⁰ yolk-shell nanospheres (Fe⁰@mC)^[47], (A-c) illustration of the synthesis of hierarchical yolk-shell Fe@SiO₂/Ni nanocomposites^[59], (B) schematic illustration of the synthetic procedure for Fe@PMO with Janus structure^[48], (C) schematic illustration of in situ confined thermal reduction strategy for preparation of corchorifolius-like structure carbon-coated Fe microspheres (CL-Fe@C)^[49], (D-a) schematic illustration of the nZVI@OMC^[46],(D-b) schematic of nanoscale zero-valent iron in mesoporous carbon (nZVI @C)^[65]

4. (A) Enhanced Cr(VI) removal mechanism of liquid nitrogen treated ZVI^[50], (B) S-nZVI for As(III) removal from aqueous solutions^[53], (C) proposed mechanism of Pb(II) removal using the g-nZVI^[69], (D) schematic diagram of the mechanism of metal ion reduced by Fe@PMO with Janus and core shell nanostructure^[48]

5. (A) Scheme of the mechanism of electrocatalytic reduction of nitrate on the CL-Fe@C in a different electrolyte^[49], (B) proposed mechanism for NRR on Fe@NeC^[71], (C) reaction mechanism of FeN-NC for nitrate reduction^[72]