Fig. 1: Structural characterizations.

a XRD patterns of as-prepared catalysts. b Co K-edge EXAFS spectra of STC and STLC. c Normalized Co K-edge XANES spectra of STC and STLC samples and the standard Co foil and CoO as reference. d FT k3χ(R) Co K-edge EXAFS of STC and STLC. Inset, schematics of the compositions in the STC and STLC. e Raman spectrum of as-prepared catalysts. f HRTEM images of ST and STLC. g EPR spectra of as-prepared catalysts.