Cobalt Oxides Anchored Ti₃AlC₂ MXene for Efficient Removal of Antibiotic Ornidazole in Water

Abstract This paper presents a novel method for synthesizing CoO_x/Ti₃AlC₂ composite catalysts using MAX‐phase Ti₃AlC₂ without etching the Al layer. By employing simple alkali precipitation and high‐temperature calcination, the resulting CoO_x/Ti₃AlC₂ catalyst demonstrated superior performance in the peroxymonosulfate (PMS) degradation of ornidazole (ONZ) compared with CoO_x/Ti₃C₂ (MXene). The CoO_x/Ti₃AlC₂‐0.05+PMS catalyst achieved complete ONZ degradation (30 mg L⁻¹) within 30 min, significantly outperforming CoO_x/MXene‐0.05+PMS, which only achieved 91% removal. The degradation rate constant (Kobs) for CoO_x/Ti₃AlC₂‐0.05+PMS (0.19325 min⁻¹) is nearly twice that of CoO_x/MXene‐0.05+PMS (0.08412 min⁻¹), highlighting the crucial role of the Al layer in catalyst activation. Characterization revealed a uniform CoO_x nanoparticle dispersion on Ti₃AlC₂, and the CoO_x/MXene‐0.05 system demonstrated high stability and adaptability in natural water with minimal Co ion leaching. Additionally, radical scavenging and electron paramagnetic resonance (EPR) spectroscopy elucidated the reactive oxygen species (ROS) generation mechanisms and identified 11 ONZ degradation intermediates, suggesting potential degradation pathways. This approach eliminated Al etching and offered a cost‐effective and environmentally friendly method for catalyst synthesis.