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 (E_f) 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.

It is urgent to control trichloroethylene (TCE) due to its harmful effect on the environment and humans. Here, a post-plasma-catalytic (PPC) system combining Mn–Ce/HZSM-5 catalysts and a corona discharge reactor was developed for TCE degradation. Among the tested catalysts, MnCe₁/HZSM-5 (Ce/Mn molar ratio = 1) showed the best catalytic performance due to its better reducibility and higher content of adsorbed oxygen. The PPC configuration markedly lowered the activation temperature of the catalyst. Then, the optimization of the TCE degradation process in the PPC system was performed using response surface methodology. The results showed that the discharge power was the dominant factor affecting the TCE degradation process, followed by the gas flow rate and relative humidity (RH). The optimum TCE removal efficiency of 99.9%, CO₂ yield of 52.84% and CO yield of 22.74% were obtained under the following operating conditions: discharge power 1.13 W, gas flow rate 0.5 L min⁻¹ and RH 18.77%. The stability of the PPC system over the MnCe₁/HZSM-5 catalyst was successfully evaluated by a long-time test. Finally, the TCE degradation pathway in the PPC system was also proposed. This study strengthens the understanding of the TCE decomposition mechanism and paves a way for quantitative control of TCE in the PPC system.

In this study, a multi-pin-to-plate negative corona discharge reactor was employed to degrade the hazardous compound trichloroethylene (TCE). The response surface methodology was applied to examine the influence of various process factors (relative humidity (RH), gas flow rate, and discharge power) on the TCE decomposition process, with regard to the TCE removal efficiency, CO₂ and CO selectivities. The variance analysis was used to estimate the significance of the single process factors and their interactions. It has been proved that the discharge power had the most influential impact on the TCE removal efficiency, CO₂ and CO selectivities and subsequently the gas flow rate, and finally RH. Under the optimal conditions with 20.83% RH, 2 W discharge power and 0.5 l min^–1 gas flow rate, the optimal TCE removal efficiency (86.05%), CO₂ selectivity (8.62%), and CO selectivity (15.14%) were achieved. In addition, a possible TCE decomposition pathway was proposed based on the investigation of byproducts identified in the exhaust gas of the non-thermal plasma reactor. This work paves the way for control of chlorinated volatile organic compounds.