TiO2 Nanotube Arrays Decorated with Graphene/Graphite Oxide Nanocomposite for the Photocatalytic Degradation of Anticancer Drugs in the Aquatic Environment

In this study, graphene–graphite oxide nanocomposite-decorated TiO2 nanotube arrays (GGO-TNAs) were synthesized by using electrochemical exfoliation and anodizing methods. The influence of GGO content on the material and photocatalytic properties of GGO-TNAs was systematically investigated for the degradation of six anticancer drugs─irinotecan, doxorubicin, capecitabine, ifosfamide, cyclophosphamide, and methotrexate─using LC-MS/MS. The efficacy of anticancer drug degradation was evaluated in both pure water and hospital wastewater, with GGO-TNAs showing superior performance compared to TNAs. GGO-TNAs featured well-defined porous TiO2 nanotube arrays (anatase phase, (101) orientation, tube diameter ∼100 nm, thickness ∼16.2 μm) decorated with graphene sheets and graphite oxide particles. By varying the GGO solution concentration (10–40 mg L–1), carbon concentrations in GGO-TNAs ranged from 4.3 to 9.5 at. %. Surface and structural compositions were confirmed by XPS and Raman spectroscopy, while EPR results indicated the generation of highly active •OH and O2•– radicals under UV–vis irradiation. The GGO (20 mg L–1, 6.9 at. % C)-TNAs exhibited the highest photocatalytic activity with first-order rate constants (k) ranging from 4.8 × 10–2 to 40.3 × 10–2 min–1, significantly outperforming TNAs alone (1.2–1.8 times higher). GGO-TNAs retained 97% of their initial efficiency after five cycles of reuse, indicating material stability. The enhanced photocatalytic performance is attributed to improved utilization of visible light, increased generation of photocarriers, and reduced recombination of electron–hole pairs. Furthermore, the relationship between k values and the physicochemical properties of the anticancer drugs was investigated, and a degradation pathway for capecitabine was proposed based on MS spectra analysis. This study demonstrates that GGO-TNAs are highly effective and stable photocatalysts for degrading anticancer drugs in water and wastewater, offering a promising solution for environmental remediation. The enhanced photocatalytic efficiency and reusability of GGO-TNAs highlight their potential for practical water treatment applications.