Round-the-clock photocatalytic memory systems: Phenomenon and applications

Semiconductor (SC) photocatalysis based on solar energy are progressively paving their ways toward the advancement of energy and environmental technologies and applications. Nonetheless, to expand their potential, studies have also been focused to make the activation of such catalytic reactions independent of photons and upgrade their activity not only under light irradiation but also in the dark. Thereby, it essentially enables the catalytic reactions round-the-clock from day to night. The construction of such catalytic materials requires an SC and a supporting material to accept/store the electrons during the light irradiation and supply them back in dark. Such phenomenon is essentially known as the “catalytic memory,” where the portion of photoinduced electrons, which stored in the material under illumination, reacts with adsorbed oxygen or water molecules and degrades pollutants under dark conditions at ambient temperature and pressure. This capacity of round-the-clock photocatalytic (PC) activity is significant toward the degradation of pollutants in wastewater or air, where it can be expanded toward designing the materials at low cost with low energy consumption. As a matter of fact, the exploitation of such PC memory systems has emerged as a promising field as a step forward toward producing more efficient PC materials for the degradation of various toxic organic pollutants, detoxification of heavy metal ions, bacterial disinfection, and hydrogen generation.