Materials and Mechanisms of Photo‐Assisted Chemical Reactions under Light and Dark Conditions: Can Day–Night Photocatalysis Be Achieved?

Abstract The photoassisted catalytic reaction, conventionally known as photocatalysis, is expanding into the field of energy and environmental applications. It is widely known that the discovery of TiO 2 ‐assisted photochemical reactions has led to several unique applications, such as degradation of pollutants in water and air, hydrogen production through water splitting, fuel conversion, cancer treatment, antibacterial activity, self‐cleaning glasses, and concrete. These multifaceted applications of this phenomenon can be enriched and expanded further if this process is equipped with more tools and functions. The term “photoassisted” catalytic reactions clearly emphasizes that photons are required to activate the catalyst; this can be transcended even into the dark if electrons are stored in the material for the later use to continue the catalytic reactions in the absence of light. This can be achieved by equipping the photocatalyst with an electron‐storage material to overcome current limitations in photoassisted catalytic reactions. In this context, this article sheds lights on the materials and mechanisms of photocatalytic reactions under light and dark conditions. The manifestation of such systems could be an unparalleled technology in the near future that could influence all spheres of the catalytic sciences.