On the Similarity and Dissimilarity between Photocatalytic Water Splitting and Photocatalytic Degradation of Pollutants

The last four decades have shown a remarkable increase in scientific interest in photocatalysis as a tool for tackling the world's energy and waste problems. The apparent similarity between photocatalytic water splitting and photocatalytic degradation of pollutants, which have been studied so far by two different scientific communities, raises the question regarding the extent to which one may utilize knowledge obtained in one field for the benefit of the other. This review examines the common features and differences between the two areas. The main similarities stem from the common dependence on the absorption of photons and on subsequent charge-carrier dynamics. The main dissimilarities are linked to thermodynamics, the type of reactants and end products, and to the role of adsorption and desorption. At present the fundamental differences between storing energy and using it to solve environmental issues affect practical solutions. Yet, easy transfer of knowledge, research resources, and personnel between the two is not only possible but should be encouraged.