Hydro-Catalytic Reclamation (HCR): A Perspective on Simultaneous Water Purification and Hydrogen Generation Using Magnetically Recoverable GQD-TiO₂ Nanocomposites

The twin crises of water scarcity and clean energy demand an integrated approach to resource management. This perspective introduces the Hydro-Catalytic Reclamation (HCR) framework, a visionary solar-powered approach for concurrent wastewater purification and hydrogen fuel production. At its core is a multifunctional nanocomposite catalyst of titanium dioxide (TiO\textsubscript{2}) sensitized by Graphene Quantum Dots (GQDs) with a magnetic Fe\textsubscript{3}O\textsubscript{4} core. This architecture enables broad-spectrum light harvesting for two simultaneous processes: (1) the photocatalytic degradation of persistent pollutants, microplastics, and pathogens into benign products; and (2) the photoelectrochemical splitting of water to generate high-purity hydrogen. Drawing on recent advances in nanomaterial design, this article surveys the state of the art, provides mechanistic insights, addresses key engineering challenges, and outlines future directions, positioning HCR as a paradigm-shifting solution that transforms wastewater from a liability into a valuable asset for global sustainability.