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Keywords
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Artificial photosynthesis, Carbon aerogel, Manganese oxide, Nanotechnology, Oxygen, Self-healing, Water oxidation
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Abstract
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The water-oxidizing complex or oxygen-evolving complex in plants, algae and cyanobacteria is an Mn4CaO5 cluster catalysing light-induced water oxidation. Herein we report that nano-sized Mn oxide/carbon aerogel is an active and low-density catalyst toward water oxidation. The composite was synthesized by a simple, low-cost procedure with different
ratio of carbon aerogel to Mn oxide and characterized by scanning electron microscopy, energy-dispersive spectroscopy, high resolution transmission electron microscopy, X-ray diffraction, electronic spectroscopy, Fourier transform infrared spectroscopy, and atomic absorption spectroscopy. Then, the water-oxidizing activity of this composite was considered in the presence of cerium(IV) ammonium nitrate. The composites with a high ratio of Mn oxide to carbon aerogel are good Mn-based catalysts with turnover frequencies of ~0.33 (mmol O2/(mol Mn$s)). In addition to the water-oxidizing activities of these composites under different conditions, their self-healing reaction in the presence of cerium(IV) ammonium nitrate was studied. We also compare the composite with graphene quantum dots/Mn oxide, which is not stable under these conditions. Using hydrogen to store sustainable energies is a promising strategy in the near future and our results show that nano-sized Mn oxide/carbon aerogel is a promising catalyst for water-splitting systems toward hydrogen evolution.
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