Manganese oxide as a water-oxidizing catalyst: from the bulk to Ångström-scale

From manganese complexes to nano-sized manganese oxides as water-oxidizing catalysts for artificial photosynthetic systems: Insights from the Zanjan team

“…Such compounds under optimum conditions show more than three times higher water-oxidizing activity than the previously reported MneCa oxides [19]. The next results also showed that small [41], but not very small [42], Mn oxides are very good catalysts for water oxidation at least in the presence of Ce(IV). The order of increasing activity toward water oxidation catalyzed by Mn oxides is as follows: nano-sized > bulk~Ångstr€ om-scale, most probably due to the fragile structure at the Ångstr€ om-scale [42].…”

“…The next results also showed that small [41], but not very small [42], Mn oxides are very good catalysts for water oxidation at least in the presence of Ce(IV). The order of increasing activity toward water oxidation catalyzed by Mn oxides is as follows: nano-sized > bulk~Ångstr€ om-scale, most probably due to the fragile structure at the Ångstr€ om-scale [42]. The ångstr€ om-scale Mn oxides in the presence of Ce(IV) significantly oxidize to MnO 4 À ions [42].…”

“…The order of increasing activity toward water oxidation catalyzed by Mn oxides is as follows: nano-sized > bulk~Ångstr€ om-scale, most probably due to the fragile structure at the Ångstr€ om-scale [42]. The ångstr€ om-scale Mn oxides in the presence of Ce(IV) significantly oxidize to MnO 4 À ions [42]. In the biological site of water oxidation, amino acid side chains help to stabilize the very small and fragile Mn cluster [42].…”

“…The ångstr€ om-scale Mn oxides in the presence of Ce(IV) significantly oxidize to MnO 4 À ions [42]. In the biological site of water oxidation, amino acid side chains help to stabilize the very small and fragile Mn cluster [42]. In other words, the Mn-stabilizing protein (PsbO) that is present in all O 2 -evolving photosynthetic organisms shields the WOC unit from the thylakoid lumen [43].…”

Water-oxidizing activity of ZSM-5 type manganosilicate: The importance of the Mn O Mn bonds

“…Nano-sized manganese oxides on faujasite zeolite show the wateroxidizing activity in the presence of ammonium cerium(IV) nitrate (Ce(IV)) with TOF of 2.62 [42]. However, Angstrom scale manganese oxides within zeolite Y show no significant wateroxidizing activity because of the high rate of decomposition to MnO 4 À [43].…”