In Situ Regeneration of Oxidized Copper Flakes Forming Nanosatellite Particles for Non‐Oxidized Highly Conductive Copper Nanocomposites

Abstract Copper (Cu) is an attractive low‐cost alternative to silver or gold. However, it is susceptible to oxidation in air. Here, facile in situ regeneration of oxidized Cu flakes (CuFLs) for the synthesis of highly conductive non‐oxidized nanocomposites is reported. The oxidized CuFLs are regenerated into non‐oxidized CuFLs and Cu nanosatellite (CuNS) particles by formic acid‐aided in situ etching and reduction reaction in soft epoxy matrix. The average particle size of CuNS particles is only 3.3 nm with an interparticle distance of 2.7 nm. Furthermore, the negligible potential barrier height between Cu and epoxy dramatically increases the electrical conductivity (66 893 S cm −1 ) of the nanocomposite (Cu = 46 vol%) by more than three orders of magnitude. The thermal conductivity is also highest (85.1 W m −1 K −1 ), compared with Cu‐based nanocomposites in literature. The conductivities are invariant in air for more than 95 days. The simple scalable in situ regeneration of oxidized CuFLs may find immediate industrial applications.