Recent developments in solar water-splitting photocatalysis

Although photovoltaic cells have great potential for supplying carbon-free energy, they suffer from the lack of an efficient and cost-effective energy storage process that can supply energy for transportation and nighttime use. A direct way to convert solar energy into chemical fuels would solve this problem. Of several possible schemes, the photon-driven electrolysis of water to produce hydrogen and oxygen has been studied most. Photoelectrolysis of water can be achieved with either self-supported catalysts or with photoelectrochemical cells. This article will introduce the basic principles of solar water splitting and highlight recent developments with semiconductor light absorbers and co-catalysts. The role of combinatorial approaches in identifying new metal oxide visible light-absorbing semiconductors will be briefly described, and the potential of using nanomaterials for more efficient devices will be discussed. Separate articles in this special issue will focus on recent developments in water-splitting concepts.