π–π Interaction and Interfacial Charge Separation of Spindles‐Layered CeO ₂ /N, S‐rGO Nanocomposites via Visible‐Light‐Induced Photocatalytic Coexistence Activity for Antibiotic Degradation and Hexavalent Chromium Reduction

The development of sustainable and efficient photocatalysts for wastewater remediation is essential due to persistent contamination from antibiotics and toxic heavy metal ions. In this study, a spindle‐shaped CeO 2 /nitrogen‐ and sulfur‐co‐doped reduced graphene oxide (CeO 2 /N, S‐rGO) heterostructure was successfully synthesized for the simultaneous removal of tetracycline (TC) and Cr(VI) under visible‐light irradiation. The CeO 2 /N, S‐rGO nanocomposite exhibited significantly enhanced photocatalytic activity, achieving ~2.2‐fold higher TC degradation ( κ = 0.0313 min −1 ) and ~2.4‐fold higher Cr(VI) reduction efficiency ( κ = 0.0416 min −1 ) within 60 min compared with pristine CeO 2 . The enhanced performance originates from the synergistic interaction between CeO 2 and N, S‐rGO, which promotes visible‐light absorption, efficient interfacial charge transfer, and suppressed electron–hole recombination. Ultraviolet‐visible diffuse reflectance spectroscopy (UV–DRS) analysis confirmed improved optical absorption due to strong π–π interactions and electronic coupling within the heterostructure. Radical scavenging experiments revealed that •OH radicals and h + species predominantly govern TC degradation, whereas photogenerated electrons and •O 2 − radicals mainly drive Cr(VI) reduction. Liquid chromatography‐mass spectrometry (LC–MS) analysis further identified the degradation intermediates and proposed possible mineralization pathways. The findings demonstrate that CeO 2 /N, S‐rGO is a promising visible‐light‐responsive photocatalyst for the simultaneous removal of organic and inorganic pollutants from wastewater systems.