Fig. 2.

Characterizations of morphologies and chemical states for S−In catalysts. a SEM image and HRTEM image (insert) of S2−In catalyst. b STEM image of S2−In catalyst and the corresponding EDS elemental mapping. c In K-edge XANES spectra for S2−In catalyst before and after reaction. d In situ In K-edge XANES spectra for S2−In catalyst at −0.98 V versus RHE. e and f In 3d and S 2p XPS spectra of S−In catalysts