Fig. 1: Characterizations of RF/C-TaSA.

a Synthetic route of RF/C-TaSA. b HAADF–STEM and SEM (inset) images of C-TaSA and RF/C-TaSA. c High-resolution XPS spectra of Ta 4 f for Ta2O5, TaN and RF/C-TaSA. d XANES of Ta foil, Ta2O5, TaN and RF/C-TaSA at tantalum L3-edge. e Wavelet transformation for the tantalum L3-edge XAFS signals of Ta foil, Ta2O5, TaN and RF/C-TaSA based on Morlet wavelets with optimum resolution at the first and higher coordination shells. Intensity increases in the order of red, yellow, green and blue. f Fourier-transformed (FT) k3-weighted R-space EXAFS spectra of Ta foil, Ta2O5, TaN and RF/C-TaSA, and g fitting result of RF/C-TaSA. Source data are provided as a Source Data file.