Fig. 1: The geometric configurations and atomic compositions of Fe sites in FER zeolite.
From: Single iron redox sites boost Methanol-SCR at low temperature
a HAADF-STEM and spherical aberration-corrected HAADF-STEM images of 0.6Fe-FER zeolite, as well as HAADF-STEM image of 1.2Fe-FER zeolite. b XANES spectra of Fe-FER zeolites with Fe foil, FeO, and α-Fe2O3 as references. c Pre-edge spectra of Fe-FER zeolites with FeO and α-Fe2O3 as references. The fitted peaks in blue and purple represent Fe2+ and Fe3+, respectively. A distinctive feature of the pre-edge spectrum of bulk α-Fe2O3 is the contribution at approximately 7115 eV (shown in light grey), which is attributed to non-local transitions into the orbitals of nearest-neighbor Fe atoms. d Variogram of the integrated intensity and centroid position of the pre-edge peak of the Fe-FER zeolites. e Wavelet transform spectra of Fe foil, FeO, α-Fe2O3, and 0.6Fe-FER. f Mössbauer spectra collected at 300 °C of 0.4Fe-FER, 0.6Fe-FER, and 1.2Fe-FER zeolites. The fitted peaks in red, green, blue and purple represent component I, component II, component III, and component IV, respectively. g Position of B-, C-, F- and G-site in the extra-framework of FER zeolite, looking along the ten-ring channels (left) and the eight-ring channels (right).
