Mechanism of water oxidation by nanolayered manganese oxide: a step forward

Abstract

New insights into the mechanism of water oxidation by layered Mn oxide are reported.

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

“…3), and another mechanism is related to the attack of an outer-sphere water molecule on an OH group that is coordinated to a high-valent Mn ion in the oxide phase (pathway i in Fig. 3) [47,48]. Interestingly, we observed these two ranges for water oxidation for nano-layered Mn oxides, at least, at pH ¼ 6.3 [48].…”

“…These results indicate that other scenarios are possible found that such exchanges are too slow [47]. But the question is open if the water exchange in the presence of Ce(IV) or [Ru III (bpy) 3 ] 3þ , not in non-pure water, and under the water-oxidation conditions remains slow or not.…”

“…4). As we discussed, the mechanism i is most probably the true mechanism in the presence of Ce(IV) [47].…”

“…Thus, the pathway ii may not be the main mechanism for water oxidation in the presence of Ce(IV). Generally, two mechanisms for water oxidation were proposed in the presence of layered Mn oxides [47]. The first one is a mechanism with very low overpotential related to the reaction between two OH groups that are coordinated to high-valent Mn ion(s) (pathway ii in Fig.…”

The effect of different metal ions between nanolayers of manganese oxide on water oxidation

“…Among Mn oxides, nanolayered Mn oxides with different organic or inorganic ions between layers are efficient and stable in water oxidation [41]. Inspired by the WOC, layered MnACa oxides were reported as efficient catalyst for water oxidation [42][43][44][45][46][47][48][49][50][51][52][53][54][55]. X-ray absorption spectroscopy (XAS) reveal similarities between layered oxide and MnACa cluster in PSII [42].…”