Size-controlled preparation of Cu2O nanoparticles from waste printed circuit boards by supercritical water combined with electrokinetic process

► We report a size-controlled process for preparing nano-Cu2O from waste PCBs. ► Highly uniform and spherical nano-Cu2O was prepared directly from waste PCBs. ► Up to 90 wt% of the Cu in waste PCBs was recovered as nano-Cu2O in this study. ► Effect of reaction condition on prepared nano-Cu2O was studied.