Water oxidation is an energy-consuming,
four-electron-transfer
reaction and is essential for solar fuel production from water. Catalysts
based on precious metals such as RuO2 and IrO2 show high efficiency for oxygen evolution reaction. However, these
catalysts are less abundant and expensive. To date, earth-abundant
water oxidation catalysts still exhibit less activity for water oxidation.
Herein, we report the synthesis of high surface area Mn2O3 nanomaterials for an efficient photocatalytic water
oxidation catalyst. The synthesis process involves three simple steps.
In the first step, CaMnO3 is synthesized by the citrate-gel
method. In the second step, CaMnO3 is transformed into
freestanding layers of ε-MnO2 by selective removal
of Ca2+. In the third step, these layers are converted
into irregularly shaped two-dimensional Mn2O3 flakes (AD-Mn2O3) by calcination at 550 °C.
These AD-Mn2O3 nanostructures show 4 times higher
surface area (127 m2 g–1) when compared
to the irregularly shaped Mn2O3 nanoparticles
(CG-Mn2O3) synthesized by the citrate-gel method
at the same temperature. The AD-Mn2O3 nanostructures
show super hydrophilicity with a contact angle of zero degree. This
material exhibits excellent photocatalytic water oxidation activity
with a turnover frequency of 1.53 × 10–3 s–1, which is twice the activity shown by CG-Mn2O3. This study can help in developing an earth-abundant,
cost-effective, efficient catalyst for overall water splitting.
Er3+, Yb3+ co-doped NaBi(MoO4)2 nanomaterials show excitation dependent photoluminescence properties in the visible and NIR regions upon excitation with UV, visible and NIR light.
Artificial photosynthesis is a promising method that directly transforms solar energy into chemical energy. To achieve artificial photosynthesis, efficient water oxidation catalysts (WOCs) are essential. In nature, the manganese-oxo-calcium cluster...
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