The cause and mechanism behind this (CN)2 release has so far been sparsely discussed in the literature. Dreyer et al. highlight how the conductive salt impacts its release, suggesting that salts such as NaClO4 preferentially oxidise forming ClOx that in turn facilitates the formation of Fe 4+ that allows for increased (CN)2 release . In contrast, they also show that the decomposition of NaPF6 does not influence Fe redox. However, excluding the impact of the salt, the primary consensus for (CN)2 release from PBAs arises from reductive elimination of the Fe centres while in an overcharged state This is immediately followed by a reductive elimination step where two CN ligands are released in the form of (CN)2 gas. Finally, since the electrode is in a highly oxidative environment at this state, it is further oxidised back to the Fe 3+ state taking up two new ligands from the electrolyte, noted here as "Y" . However, as previously discussed, the reductive elimination step is not electrochemically controlled, and therefore, we have proposed an alternative route, Route B in Figure (a). Here, the desodiated PW is further oxidised, pushing the Fe to the 4+ state, while taking up an additional negative ligand, denoted as Y, from the electrolyte. This is then followed by a reductive elimination step that releases a CN ligand. This can continuously happen if the potential is further increased, allowing for the formation of a similar final product as suggested from Route A. In order to corroborate these findings, MöS was conducted on a pristine and an overcharged (up to 4.6 V vs Na + /Na) PW sample as shown in Figure . Overall, it is clear from the spectra that the sample is degraded since the peak widths are wider, there is at least one new Fe environment present and the resolution (separation between the peaks) is low. From the spectra it is not possible to assign accurate spectral areas or the resulting relative ratios due to the broad peaks.