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Today, as a result of the advancement of technology and increasing environmental problems, the need for clean energy has considerably increased. In this regard, hydrogen, which is a clean and sustainable energy carrier with high energy density, is among the well-regarded and effective means to deliver and store energy, and can also be used for environmental remediation purposes. Renewable hydrogen energy carriers can successfully substitute fossil fuels and decrease carbon dioxide (CO2) emissions and reduce the rate of global warming. Hydrogen generation from sustainable solar energy and water sources is an environmentally friendly resolution for growing global energy demands. Among various solar hydrogen production routes, semiconductor-based photocatalysis seems a promising scheme that is mainly performed using two kinds of homogeneous and heterogeneous methods, of which the latter is more advantageous. During semiconductor-based heterogeneous photocatalysis, a solid material is stimulated by exposure to light and generates an electron–hole pair that subsequently takes part in redox reactions leading to hydrogen production. This review paper tries to thoroughly introduce and discuss various semiconductor-based photocatalysis processes for environmental remediation with a specific focus on heterojunction semiconductors with the hope that it will pave the way for new designs with higher performance to protect the environment. [ABSTRACT FROM AUTHOR]

[Display omitted] • UVC/persulfate activation was enhanced by coupling with SCF@GCN composite. • Complete elimination of BPA was achieved in 15 min with k obs = 0.32 min−1. • Both radical and non-radical mechanisms were involved during the degradation process. • Transfer pathway of photo-induced e-/h+ followed the direct S-scheme mechanism. • An excellent synergistic effect was obtained for SCF@GCN/PS/UVC hybrid system. This study was designed to enhance wastewater treatment by the UVC/persulfate process via its coupling with spinel cobalt ferrite (SCF) nanoparticles anchoring graphitic carbon nitride (g-C 3 N 4 , GCN). The performance of SCF@GCN was assessed against bisphenol A (BPA) degradation as a model recalcitrant contaminant. Characterization tests confirmed the successful preparation of SCF@GCN with high photocatalytic activity and excellent capability in PS activation compared to plain SCF or pristine GCN. The results strongly pointed out that SCF@GCN combined with UVC and PS is capable to rapidly degrade BPA with a remarkable synergistic effect. Under optimum conditions (pH: 9.0, SCF@GCN: 0.3 g/L and PS: 4.0 mM), complete elimination of BPA (40 mg/L) was achieved in 15 min with excellent degradation kinetics (0.32 min−1). Scavenging experiments ascertained the generation of h+, 1O 2 , O 2 •− , SO 4 •−, HO• species in SCF@GCN/PS/UVC system, indicating that both radical and non-radical mechanisms were involved during the degradation process. Furthermore, the developed process displayed a satisfactory performance for effective treating BPA-contaminated wastewater samples. Over 95% BPA was removed by the system after five catalyst reuse cycles, suggesting a cost-effectiveness potential in the reusability of SCF@GCN. A comprehensive mechanistic pathway for BPA degradation was proposed based on the reactive species and intermediates identified: A S-scheme heterojunction mechanism of photo-generated electron/hole pairs transfer in the SCF@GCN catalyst was found. Overall, our results present a promising technique with synergistic character for intensification of wastewater treatment. [ABSTRACT FROM AUTHOR]