Fig. 2

HAADF-STEM images and XPS spectra. HAADF-STEM images of a NiVRu-LDH and b NiVIr-LDH, and the corresponding EELS mappings images. The high-resolution XPS signals of NiV-LDH, NiVRu-LDH, and NiVIr-LDH for c Ni 2p and d V 2p. The high-resolution XPS signals of Ru 3p in e NiVRu-LDH and f Ir 4 f in NiVIr-LDH