Inorganic materials acting as heterogeneous photocatalysts and catalysts in the same reactions

General considerations on the differences and similarities between heterogeneous photocatalysis and thermal catalysis are presented. Some research papers are reviewed where a reaction has been carried out in the presence of an inorganic material used both as catalyst and photocatalyst. The existing literature often compares catalytic reactions undertaken with the contemporaneous presence of radiation, showing only that photocatalytic reactions can occur under milder experimental conditions and at much lower temperatures. Nevertheless, differences in mechanistic aspects, conversions and selectivities between catalytic and photocatalytic reactions should also be highlighted. These are due to various reasons, relating to the effects of the interaction of light with the solid surface, adsorption-desorption of species involved in the (photo)reactions, and activation energy.