Recent advancements in Cadmium-based photoactive catalysts for the degradation of aromatic polycyclic hydrocarbons and hydrogen production: Synthesis, modification, and the development of hybrid systems

Polycyclic aromatic hydrocarbons (PAHs) are persistent and harmful organic pollutants that are formed during the incomplete combustion of carbonaceous substances (fossil fuels, biomass, and tobacco). Their environmental persistence, bioaccumulation, and carcinogenic properties pose serious threats to the ecosystem and human health and require effective remedial plans. It is widely accepted that hydrogen (H₂) is a clean and sustainable energy source because its combustion produces no byproducts. Photocatalytic H₂ production is a promising method for meeting the world's energy needs in the most environmentally friendly way possible. Photocatalysis is also a non-polluting technique for degrading pollutants into less harmful compounds using light energy. Cadmium sulfide (CdS) has received significant interest because of its tuneable band gap and high absorption of visible light. Nevertheless, photocorrosion, rapid charge-carrier recombination, and low stability limit its practical use. The present review focuses on the photodegradation of PAHs and H₂ production, as well as current developments in CdS-based photocatalysts. Finally, the review outlines current problems and future research prospects for developing sustainable, effective, and long-lasting CdS-based photoactive catalysts to purify the environment and generate sustainable energy.