This chapter explores multifunctional nanomaterials capable of applications beyond pollutant removal, including hydrogen generation and energy-linked environmental technologies. It examines how photocatalytic materials contribute to green hydrogen production, discussing structural features, charge-transport behavior, and reactor-scale considerations. This chapter also addresses multi-pollutant adsorption systems, competitive sorption mechanisms, and selective adsorption strategies for complex industrial wastewaters. Emphasis is placed on the challenges of real-world matrices and the need for robust material design. This chapter bridges water treatment with broader sustainability goals.