doi:10.1038/nindia.2008.323 Published online 23 November 2008
Researchers have created a novel zeolite-based catalyst that splits water to make hydrogen1. The catalyst helps produce hydrogen in the presence of visible light. Hydrogen, touted as the fuel of the future, can be produced from non-conventional and renewable sources like water.
The researchers used zeolite, a catalyst with high surface area. They devised a novel zeolite-based catalyst by incorporating titanium dioxide (TiO2), heteroployacid (HPA) and transition metals like cobalt (Co) and tested its efficacy to split water in the presence of visible light given off by tungsten filament lamp.
On exposure to visible light, HPA got reduced to HPB (heteroployblue). This HPB absorbs light in the visible range. Then the electron from HPB was transferred to cobalt ion via the zeolite framework by a hopping mechanism. Next cobalt ion transferred this electron to water that got reduced and produced hydrogen.
Presence of cobalt ion and HPA in zeolite influenced light absorption property of the catalyst and increased hydrogen yield. Cobalt ion was present in well-dispersed exchangeable form and probably acted as an electron acceptor. No hydrogen evolved in the absence of zeolite.
"Hydrogen generated photocatalytically is a cleaner substitute to existing fuel," says lead researcher Sadhana S. Rayalu from the environmental materials unit of National Environmental Engineering Research Institute (NEERI), Nagpur. The team has also used the same photocatalyst to produce non-conventional fuel like methanol.
Dubey, N. et al. Visible light active zeolite-based photocatalysts for hydrogen evolution from water. Int. J. Hydrogen Energy 33, 5958-5966 (2008) | Article |