Kagóme Cobalt(II)-Organic Layers as Robust Scaffolds for Highly Efficient Photocatalytic Oxygen Evolution
| Autor: | Qing Zhang, Zhi Wang, Jia-Heng Xu, Wenguang Wang, Di Sun, Chen-Ho Tung, Wenguang Yu |
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| Rok vydání: | 2016 |
| Předmět: |
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Molecular General Chemical Engineering Inorganic chemistry Molecular Conformation chemistry.chemical_element 010402 general chemistry Heterogeneous catalysis 01 natural sciences Catalysis Organometallic Compounds Environmental Chemistry General Materials Science Electrodes Cobalt oxide 010405 organic chemistry Chemistry Oxygen evolution Cobalt Photochemical Processes 0104 chemical sciences Oxygen General Energy Photocatalysis Water splitting Metal-organic framework Oxidation-Reduction |
| Zdroj: | ChemSusChem. 9:1146-1152 |
| ISSN: | 1864-5631 |
| DOI: | 10.1002/cssc.201600101 |
| Popis: | Two Kagóme cobalt(II)-organic layers of [Co3 (μ3 -OH)2 (bdc)2 ]n (1) and [Co3 (μ3 -OH)2 (chdc)2 ]n (2) (bdc=o-benzenedicarboxylate and chdc=1,2-cyclohexanedicarboxylate) that bear bridging OH(-) ligands were explored as water oxidation catalysts (WOCs) for photocatalytic O2 production. The activities of 1 and 2 towards H2 O oxidation were assessed by monitoring the in situ O2 concentration versus time in the reaction medium by utilizing a Clark-type oxygen electrode under photochemical conditions. The oxygen evolution rate (RO2 ) was 24.3 μmol s(-1) g(-1) for 1 and 48.8 μmol s(-1) g(-1) for 2 at pH 8.0. Photocatalytic reaction studies show that 1 and 2 exhibit enhanced activities toward the oxidation of water compared to commercial nanosized Co3 O4 . In scaled-up photoreactions, the pH value of the reaction medium decreased from 8.0 to around 7.0 after 20 min and the O2 production ceased. Based on the amounts of the sacrificial oxidant (K2 S2 O8 ) used, the yield of O2 produced is 49.6 % for 2 and 29.8 % for 1. However, the catalyst can be recycled without a significant loss of catalytic activity. Spectroscopic studies suggest that the structure and composition of recycled 1 and 2 are maintained. In isotope-labeling H2 (18) O (97 % enriched) experiments, the distribution of (16) O(16) O/(16) O(18) O/(18) O(18) O detected was 0:7.55:92.45, which is comparable to the theoretical values of 0.09:5.82:94.09. This work not only provides new catalysts that resemble ligand-protected cobalt oxide materials but also establishes the significance of the existence of OH(-) (or H2 O) binding sites at the metal center in WOCs. |
| Databáze: | OpenAIRE |
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