The increasing contamination of water resources with heavy metals and organic pollutants poses significant environmental and health challenges. Nanocomposites have emerged as promising materials for wastewater purification due to their high surface area, tunable physicochemical properties, and enhanced catalytic activity. This chapter explores the integration of doped metal oxide with graphene oxide (GO) to develop advanced nanocomposites and electrodes for efficient water treatment. The synergy between doped metal oxide and GO enhances conductivity, chemical stability, and surface reactivity, enabling exceptional performance in photocatalytic and electrochemical processes. These materials demonstrate the effective removal of toxic heavy metals and the degradation of complex organic pollutants through advanced oxidation processes (AOPs) and other catalytic mechanisms. The incorporation of dopant elements in the metal oxide optimizes photocatalytic efficiency by facilitating faster charge transfer and higher reaction rates. Furthermore, this chapter discusses the mechanisms by which organic contaminants are effectively oxidized, leading to their transformation into benign end products such as H2O and CO2. This work provides valuable insights into the role of nanocomposites in developing innovative, scalable, and sustainable solutions for addressing industrial effluents and environmental water pollution.