XRD patterns and SEM, TEM, and HRTEM images. XRD patterns of Cu2O and PtCu NCs (a). SEM image of the Cu2O template (b) and PtCu NCs (c). TEM (d) and HRTEM (e, f) images of the PtCu NCs. The insets of (b) and (c) are the SEM images of single Cu2O crystal and PtCu NC, respectively. The inset of (d) is the TEM image of a single PtCu NC. The insets of (e) and (f) are the SAED pattern and lattice fringes of PtCu NC, respectively.