Multifunctional transition metal oxide/graphene oxide nanocomposites for catalytic dye degradation, renewable energy, and energy storage applications.

The worsening global environmental and energy crises involving industrial water pollution, carbon emissions and clean, sustainable energy requirements call for innovative multifunctional materials. Transition metal oxide/graphene oxide (TMO/GO) nanocomposites represent an advanced material group through their ability to integrate redox properties of transition metal oxides and catalytic characteristics with graphene derivative characteristics, which include electrical conductivity, low surface area, and exceptional mechanical strength. While TMO/GO composites demonstrate promising multifunctional abilities in dye degradation, energy storage, and renewable energy applications, critical challenges remain unaddressed. First, scalable synthesis methods for defect-free graphene hybrids with uniform TMO nanoparticle distribution are underdeveloped, as current solvothermal or sol-gel approaches often yield inconsistent morphologies and require surfactants or toxic solvents. Second, the long-term stability of these composites under operational conditions remains poorly characterized, with limited studies on mechanical degradation or leaching of toxic metal ions. Third, while individual functionalities (photocatalysis, capacitance) are well-studied, synergistic optimization of dual/multifunctional performance is largely unexplored. This review gives a thorough examination of synthesis methods (sol-gel and hydrothermal) and metal doping protocols for surface functionalization and TMO/GO composite behavior related to their unique applications. This review gives a thorough examination of synthesis methods (sol-gel and hydrothermal) and metal doping protocols for surface functionalization and TMO/GO composite behavior related to their unique applications. The paper evaluates existing research gaps and sustainability factors by delivering an analytical assessment of the scalability as well as durability, and sustainable development applicability across next-generation clean water technologies and renewable energy conversion and energy storage systems.