Recent Advancements in Zirconium Dioxide-Graphene Oxide Nanocomposites for the Photocatalytic Degradation of Phenanthrene

Polycyclic aromatic hydrocarbons (PAHs), particularly phenanthrene, pose severe environmental threats due to their toxicity, carcinogenicity, and persistent nature. Heterogeneous photocatalysis offers a sustainable pathway to mineralize such recalcitrant contaminants. Zirconium dioxide (ZrO2) stands out as a photocatalytic medium due to its outstanding thermal stability and strong redox properties (conduction band: -1.0 eV; valence band: +4.0 eV). However, its efficiency is typically impaired by a wide bandgap and rapid recombination of electron-hole pairs. The use of cocatalysts or functional materials is effective because it enhances charge transfer, lowers recombination, and creates synergistic effects. This review is a critical analysis of how Graphene Oxide (GO) can overcome these shortcomings through the creation of ZrO2-GO nanocomposites. The integration of GO creates a Schottky-like junction, which serves as an electron sink and, simultaneously, increases pollutants’ adsorption through π-π stacking interactions with phenanthrene’s aromatic rings. Contrary to the previous research, which mainly concentrated on dyes or simple inorganics, this study specifically fills the gap in knowledge on the degradation pathways, intermediate toxicity, and pathway of mineralization of complex PAHs across ZrO2-GO-based systems. We compare recent material design approaches, such as phase engineering, green synthesis, and ternary heterojunctions, towards optimization of visible-light harvesting. Lastly, the review discusses catalyst stability under realistic wastewater conditions and the elimination of toxic products, offering a strategic roadmap for translating ZrO2-GO photocatalysts from laboratory research to scalable environmental remediation.