Immobilization of homogeneous water oxidation catalysts (WOCs) on solid supports is important for the development of devices that simulate natural photosynthesis. However, the heterogeneity of solid surfaces means that it is not easy to immobilize WOCs without loss of their original activity.

Shinji Inagaki, Toyota Central R&D Laboratories, Inc., Aichi, Japan, and colleagues have immobilized an iridium complex, which is an efficient water oxidation catalyst, without loss of activity. They used a bipyridine-periodic mesoporous organosilica (BPy-PMO) as a solid support. The iridium complex was directly formed on the pore surface of BPy-PMO by postsynthetic metalation of the framework bipyridine ligands.

The immobilized iridium catalyst showed a good performance in the water oxidation reaction using cerium(IV) ammonium nitrate as an oxidant. The performance was comparable to that of an analogous homogeneous iridium catalyst. Furthermore, the BPy-PMO-based iridium complex could be recovered easily by filtration and reused at least three times with little loss of activity. These results demonstrate the potential of BPy-PMO as a platform for the construction of artificial-photosynthesis systems.

• Heterogeneous Catalysis for Water Oxidation by an Iridium Complex Immobilized on Bipyridine-Periodic Mesoporous Organosilica,
  Xiao Liu, Yoshifumi Maegawa, Yasutomo Goto, Kenji Hara, Shinji Inagaki,
  Angew. Chem. Int. Ed. 2016.
  DOI: 10.1002/anie.201601453

Correction (July 14, 2016)
The article originally included a different picture.