Fundamentals of photoelectrocatalysis

Photoelectrocatalysis combines heterogeneous photocatalysis and electrocatalysis principles for numerous processes including the degradation of harmful compounds, the generation of H2 and O2 from water splitting, the reduction of CO2 or the photoelectrocatalytic synthesis of valuable organic molecules otherwise difficult to be synthetized with classical approaches. The recent progress of photoelectrocatalysis is heavily related to the development of materials, especially in 2D and nano materials. Highly ordered nanomaterials such as graphene, nanotubes, nanowires, etc. are gaining more attention due to their high surface area and excellent conductivity. Other challenges are the development of stable semiconductor materials able to be activated by solar radiation. In fact, the method is based on the use of a semiconductor irradiated by light energy equal or greater than its band gap energy simultaneously biased by a gradient potential. Therefore, to better understand the photoelectrocatalytic processes it is important to handle both the fundamental aspects related to photocatalysis and electrocatalysis, and the scope of this chapter is actually to fulfil this gap.