Interface-engineered TiO2 molecularly imprinted photocatalysts with synergistic adsorption–photocatalysis enhancement for metronidazole removal in real wastewater

Conventional photocatalysts often show limited efficiency in complex aqueous matrices because reactive oxygen species (ROS) are rapidly scavenged by competing solutes. To overcome this limitation, TiO 2 –polymer hybrids bearing molecularly imprinted adsorption sites selective toward metronidazole (MNZ) were synthesised to preconcentrate the pollutant near the photocatalyst surface. Molecularly imprinted (MIP) and non-imprinted (NIP) materials with different polymer-to-TiO 2 mass ratios were prepared to examine how interfacial polymer architecture affects adsorption and photocatalytic performance. Structural and optical analyses confirmed the formation of a thin surface-confined polymer layer that preserved the TiO 2 crystal structure while introducing adsorption centres. All materials followed Langmuir adsorption behaviour. MIPs exhibited 3–4-fold higher adsorption capacities than NIPs and pseudo-second-order kinetics consistent with cavity-driven MNZ binding, whereas NIPs showed faster but non-specific uptake. Under UV irradiation, photocatalytic activity correlated with these interfacial features. MIP_1:10 and MIP_1:5 achieved the highest MNZ removal (∼95%), indicating that increased recognition-site density can offset light attenuation at higher polymer loadings. In municipal wastewater, efficiencies decreased, but MIPs consistently outperformed NIPs. These results show that imprinting-layer thickness and interfacial architecture govern the balance between selective adsorption and photocatalytic degradation in TiO 2 -based hybrids.