Engineering rGO@CeO₂/Co₃O₄ nanocomposite for dual-functional electrocatalysis in solar energy conversion and environmental remediation

The multifunctional rGO@CeO₂/Co₃O₄ nanocomposite, designed for solar energy conversion, and pollutant degradation applications, was successfully synthesized using a sol–gel approach. Structural, morphological, and chemical analyses were performed using XRD, SEM, and XPS techniques. XRD results confirmed the crystalline phases of CeO₂ and Co₃O₄, while the absence of the characteristic rGO peak indicated its uniform dispersion within the composite matrix. SEM observations revealed that the incorporation of rGO transformed the aggregated morphology into interconnected nanosheet structures, providing a conductive network that reduced particle agglomeration and enhanced charge transport. XPS analysis confirmed the coexistence of Ce⁴⁺/Ce³⁺ and Co³⁺/Co²⁺ oxidation states, indicating strong interfacial electronic interactions between rGO and the metal oxides. Owing to the synergistic effect of improved conductivity, efficient charge separation, and increased active surface area, the rGO@CeO₂/Co₃O₄ electrode exhibited superior electrochemical performance. When employed as a counter electrode in dye-sensitized solar cells (DSSCs), the hybrid nanocomposite achieved a power conversion efficiency of 9.2 ± 0.02%, exceeding both CeO₂/Co₃O₄ and conventional Pt electrodes. In photocatalytic studies, the composite demonstrated an excellent tetracycline degradation efficiency of 98%, significantly higher than the comparison electrodes. The enhanced multifunctional performance is mainly attributed to the synergistic interaction between rGO and CeO₂/Co₃O₄, which facilitates rapid electron transport, suppresses charge recombination, and increases the number of active catalytic sites. These findings demonstrate the potential of rGO@CeO₂/Co₃O₄ as an efficient and sustainable material for next-generation photoelectrochemical and environmental remediation applications.