Sustainable hydrogen production by the application of ambient temperature photocatalysis

Hydrogen production by water splitting is a holy grail of science, being one route to a non-fossil fuel and a potential source of clean energy. It is essential to use a non-polluting energy source to drive the reaction and one way is to utilise sunlight energy, combined with a way to overcome the kinetic limitations of the reaction. The production of hydrogen by the photocatalytic cleavage of water can overcome these energetic hurdles. This area of science is briefly reviewed here, focussing on two routes, namely i) the use of sacrificial agents such as alcohols to act as oxygen scavengers and liberate hydrogen only and ii) by direct water splitting to produce both hydrogen and oxygen. The factors which are important in determining the characteristics of effective photocatalytic water splitting systems are elucidated.