Fig. 2: Characterizations for the W-TNT samples.

a XRD patterns of W-TNT-300 and TNT. b HR-TEM image of W-TNT-300. c STEM-EDS mapping image of W-TNT-300. d–f HAADF-STEM images of the 54%W-TNT-600, W-TNT-600, and W-TNT-1000, insets show the intensity profile across the tungsten atoms indicated by the yellow solid circles. g XANES spectra and h EXAFS spectra of W foil, WO3, and 54%W-TNT-600. The color scheme of the atoms in the illustration is red (O) for oxygen, blue (Ti) for titanium, and grey (W) for tungsten. i W 4 f core level XPS spectra of W-TNT-600, W-TNT-1000, and 54%W-TNT-600. Source data are provided as a Source Data file.