Dating back to more than one century ago, the photocatalysis process has demonstrated great promise in addressing environmental problems and the energy crisis. Nevertheless, some single or binary composite materials cannot meet the requirements of large-scale implementations owing to their limited photocatalytic efficiencies. Since 2021, dual S-scheme heterojunction-based nanocomposites have been undertaken as highly efficient photoactive materials for green energy production and environmental applications in order to overcome limitations faced in traditional photocatalysts. Herein, state-of-the-art protocols designed for the synthesis of dual S-scheme heterojunctions are described. How the combined three semiconductors in dual S-scheme heterojunctions can benefit from one another to achieve high energy production and efficient oxidative removal of various pollutants is deeply explained. Photocatalytic reaction mechanisms, by paying special attention to the creation of Fermi levels (Ef) and charge carriers transfer between the three semiconductors in dual S-scheme heterojunctions, are discussed. An entire section has been dedicated to some examples of preparation and applications of double S-scheme heterojunction-based nanocomposites for several photocatalytic applications such as soluble pollutants photodegradation, bacteria disinfection, artificial photosynthesis, H2 generation, H2O2 production, CO2 reduction, and ammonia synthesis. Lastly, the current challenges of dual S-scheme heterojunctions are presented and future research directions are presented. To sum up, dual S-scheme heterojunction nanocomposites are promising photocatalytic materials in the pursuit of sustainable energy production and environmental remediation. In the future, dual S-scheme heterojunctions are highly recommended for photoreactors engineering instead of single or binary photocatalysts to drive forward photocatalysis processes for practical green energy production and environmental protection.
