Fig. 1: Fabrication of hollow MEA nanolattices.

a Schematic illustration of the two-photon lithography (TPL) technology used to fabricate polymer nanolattices that serve as a physical template for the MEA film. b Illustration of the DC magnetron sputtering process used to deposit a thin layer of CoCrNi MEA onto the polymer nanolattice scaffold. c Illustration of the octet MEA composite nanolattice during plasma ashing and after focused ion beam milling (to expose the polymer core). d Schematic depicting the hollow MEA nanolattice produced upon plasma ashing (to remove the polymer core). e–h Hierarchical structure of the as-fabricated MEA nanolattices. The insets in h are the selected area diffraction pattern (SADP) and the corresponding fast Fourier transform (FFT) along the [011] zone axis. The twin boundaries (TBs) are determined to be parallel to one set of the {111} planes. Additionally, long streaks appear along two {111} planes, indicating the existence of stacking faults (SFs).