Figure 2. Regeneration mechanism and supporting XANES spectra.

(a) Electrochemical reactions for the regeneration cycle of Cu²⁺-intercalated Bi-birnessite. The reactions taking place in each region are colour-coded and numbered corresponding to the galvanostatic and potentiodynamic curves. (b) XANES spectra of a cycled electrode in the charged state for the Mn K edge indicating match with birnessite and (c) for the Cu K-edge of the same material indicating that Cu exists as Cu²⁺ intercalated into birnessite matching ref. 37.