Photocatalytic and Catalytic Reactions in Gas–Solid and in Liquid–Solid Systems

Heterogeneous photocatalytic and thermal-catalytic reactions are here presented focusing the differences and similarities between the two processes. When possible, the comparison was made for the same chemical reaction in the presence of an inorganic material playing the role of both catalyst or/and photocatalyst. Several examples are presented where a catalytic reaction can occur at milder experimental conditions and, particularly, at lower temperature when the system is also irradiated by UV and/or visible light. The differences in mechanistic aspects, conversions, and selectivities between catalytic and photocatalytic reactions will be also considered because these occurrences are related to various reasons, and they can change due to the effects of the interaction of light with the solid surface or to the temperature that influences the adsorption–desorption of species involved in the (photo)reactions and to the activation energy consequently to the different pathways followed by the reactions.