Fig. 2: Characterization of the atomically isolated asymmetric Ni–O–Ti sites.
From: Highly selective urea electrooxidation coupled with efficient hydrogen evolution
a Atomic-resolution HAADF-STEM image of asymmetric Ni–O–Ti sites with white circles marking Ni atoms. b Corresponding line intensity profile taken along the white dashed rectangle, and (c) 3D surface intensity profile in the yellow dashed square box. d 2D black and white STEM simulation images on the basis of the Z contrasts of atomic columns and corresponding structure diagram of asymmetric Ni–O–Ti sites. e STEM elemental mapping. f Ni K-edge X-ray absorption near-edge structure spectra of the atomically isolated asymmetric Ni–O–Ti sites and connected symmetric Ni–O–Ni sites on Ti foam. g FT-EXAFS spectra and (h) wavelet transformed (WT) k3-weighted χ(k)-function of Ni K-edge of the asymmetric Ni–O–Ti sites and symmetric Ni–O–Ni sites. Ni foil and NiO were used as the standard samples.
