Nanostructured metal oxide-based nanocomposites have been widely used for photocatalysis-mediated removal of toxic substances. The search for a better photocatalyst seems relentless, and numerous metal oxide-based materials have emerged out of investigations. This overview presents the works involving the use of ZnO, CuO and NiO as photocatalysts and their modifications by way of coupling with other semiconductors for improved photodegradation in the presence of visible light. Modifications like doping or forming nanocomposites increase the stability and efficiency of pristine metal oxide nanoparticles. The constructions of various heterojunctions have been highlighted, and their performances have been duly recorded. It has emerged from this survey that nanostructured photocatalysts based on ZnO, CuO and NiO have enormous potential in water purification through photocatalytic destruction of organic pollutants. The effect of calcination temperature on the surface morphology of the prepared nanoparticles, degradation kinetics, and several ways to improve the photocatalytic activity of metal oxide nanocomposites has been summarized in this article. For instance, ZnO/CeO₂ having a bandgap of about 3 eV showed 100% photodegradation of methylene blue (MB) within a short period of time. The structures of hybrid metal oxide heterojunctions and their properties have been highlighted. The overview also briefly deliberates on issues and limitations that need to be addressed to achieve real applications.