An overview of FeS2-derived photocatalysts for wastewater remediation

The irregular monitoring and discharge of toxic industrial effluents into water bodies are major emerging concerns in the world. Among advanced wastewater treatment techniques, photo-Fenton and photocatalytic processes for the decontamination of coloured water have gained immense consideration. FeS2, a metal sulphide, is a promising photocatalyst due to of its low energy band gap, low cost, large absorption coefficient, and easy separability. However, the practical application of pristine FeS2 remains limited by the rapid recombination of photogenerated e−/h+ pairs. Recent studies demonstrate that modification strategies such as metal/non-metal doping and heterojunction construction (type-II, Z-scheme, and S-scheme systems) markedly enhance charge separation and redox ability. Reported FeS2-based heterostructures exhibit significantly improved photocatalytic performance, achieving dye degradation efficiencies exceeding 90–99% within short irradiation times under visible light, along with enhanced reaction kinetics and stability. Comparative analysis reveals that modified FeS2 composites show broader applicability, higher mineralisation rates, and superior recyclability than pristine FeS2. Finally, the current challenges, knowledge gaps, and future research directions for FeS2-based photocatalysts are discussed. Overall, this review provides valuable insights into the photocatalytic mechanisms of FeS2 systems and offers a comprehensive perspective on the degradation of different classes of dyes and their associated environmental toxicity.