Hydrogen Generation Catalyzed By Metalloporphyrins

Hydrogen has potential of being used as the future green fuel in fuel cells. The demand and consumption of hydrogen have predicted to continuously rise in the next two decades. Nevertheless, a highly efficient and low cost of water-splitting catalyst for hydrogen generation remains elusive. In this presentation, we synthesize a series of metalloporphyrin complexes in order to elucidate the effects of porphyrinic structure to the catalytic efficiencies. It is found that the metalloporphyrins with different substituents demonstrated different catalytic activities. A porphyrin with acidic substituents appears to be essential to offer high catalytic efficiencies. Additionally, a substituent located closer to the metal ion center will be better than oriented outward in respect to the central core. Our results also suggest that the type of central metal ions is another factor that control the activity of the hydrogen generation catalysts. Through the comparison on the CV of two novel N-confused porphyrin cobalt nitrosyl complexes, it appears that the activities of the catalysts depend on the reduction sites where the reducing equivalent will reside, i.e. a Co(NO) moiety based reduction has a more positive onset potential than a porphyrin-based reduction.