On 20 December 2013, the United Nations declared 2015 as the International Year of the Light. Light is an ideal candidate for Green Chemistry because photons do not give residues and, in particular, solar light is a renewable energy source. Many reactions can be driven by light and, among them; the use of photocatalysts greatly enhances the number of possible applications from both the scientific and technological points of view. Heterogeneous photocatalysts can be, in principle, easily separated and reused. Since their introduction, many improvements have been made, starting from their synthesis, composition, preparation, reactivity, regeneration, stability, reduced toxicity, and fields of application, just to cite some. This advanced interdisciplinary technology involves a wide range of subjects and many practical applications are already present in the market.

This special issue welcomes critical reviews and original papers describing the recent developments of heterogeneous photochemistry applied to Green Chemistry. In other words, energy production from biomasses, depollution, and solar energy conversion will be welcome.

Potential topics include, but are not limited to:

• Hydrogen production from biomasses
• Solar photochemistry
• Wastewater and air treatment
• Environmental photochemistry