WATER SPLITTING
Figure 1. Cobalt-based catalysts work well at ambient temperature under air.
Source: University of Cambridge. "Until now, no inexpensive molecular catalyst was known to evolve H
2 efficiently in water and under aerobic conditions. However, such conditions are essential for use in developing green hydrogen as a future energy source under industrially relevant conditions," he explains.The homogeneous cobaloxime-type material evolves H2 both electro- and photocatalytically. It provides a Farradaic efficiency of about 43% and a photo-induced H
2-evolution relative activity of about 70% under those conditions. More details appear in an article in Angewandte Chemie International.Platinum also evolves H
2. "The issue with platinum is that it's very rare and therefore expensive. It also is a good O
2-reduction catalyst, which limits its operation for H
2 evolution in the presence of O
2," notes Reisner. "We will do a direct comparison with platinum soon." "Problems of the cobaloxime catalyst are the limited lifetime (several hours) and a small turnover number (it only produces about 100 molecules of H
2 per molecule of catalyst). We need numbers in the millions here," he admits. "Development of more inexpensive and efficient systems is still required."
