File Name : fig. s1.tif

Caption : fig. s1. the amount of hydrogen produced by the manganese-containing system and the blank control group was measured at 40 ma cm−2: (a) uncycled and (b) cycled for 20 cycles at 40 ma cm-2, and the pristine electrolyte with 0.002 m mn2+: (c) uncycled and (d) cycled for 20 cycles at 40 ma cm-2.

File Name : fig. s2.tif

Caption : fig. s2. sem and eds of graphite felt before charge (a) sem; (b) o; (c) c.

File Name : fig. s3.tif

Caption : fig. s3. xps spectra of electrode after cycling in electrolyte containing mn2+