Abstract
Heterogenization of nanostructured iridium-based catalysts to simultaneously achieve activity and stability in the catalytic water oxidation with cerium ammonium nitrate (CAN) as the oxidant is reported herein. We demonstrate that a polyamine-mediated assembly process to disperse iridium species on mesoporous silica spheres facilitates the fabrication of nanosized iridium oxides under optimal thermal treatment. From comprehensive morphological and electronic structure studies including electron microscopy, UV-vis spectroscopy, XANES, and EXAFS, we show that the influence of polyamine is crucial in stabilizing catalytically active iridium oxides in the mesoporous silica matrix. While the functionalization of the silica surface with polyamine facilitates interaction with the negatively charged iridium precursor, the presence of polyamine further enables control of the dispersion and crystallization of the generated iridium oxides during the thermal treatment at 573 K. As a consequence, the catalyst exhibits enhanced activity with higher TON along with desirable stability to allow it to be recycled while keeping the activity intact. The activity and stability of the synthesized catalyst in comparison with those of IrCl3 and IrO2 reveal that balancing between the dispersion and crystallization of iridium oxides is crucial in heterogenization of the catalyst.
Original language | English |
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Pages (from-to) | 5699-5705 |
Number of pages | 7 |
Journal | ACS Catalysis |
Volume | 6 |
Issue number | 9 |
DOIs | |
State | Published - 2 Sep 2016 |
Externally published | Yes |
Keywords
- heterogeneous catalysis
- nanostructures
- oxides of iridium
- polyamine
- surface-functionalized silica
- water splitting
ASJC Scopus subject areas
- Catalysis
- General Chemistry