Fig. 4: Effects of shell thickness on the phase structure and catalytic performance.

a, b CO conversion of the Fe@Mn@xSi (a) and Fe@Mn@xSi-c (b) catalysts. c, d Hydrocarbons distribution of the Fe@Mn@xSi (c) and Fe@Mn@xSi-c (d) catalysts. e XRD patterns of the spent catalysts. f XPS spectra of Cl 2p on catalysts.