Cyclodextrin-assisted defect-rich MoWO3–x for synergistic adsorption–photocatalytic degradation of organic pollutants

Enhancing the adsorption and photocatalytic degradation of organic pollutants requires simultaneous optimization of interfacial properties and intrinsic electronic structure. Here, we report a one-pot hydrothermal synthesis of γ-cyclodextrin (γ-CD)-assisted molybdenum tungsten oxide (γ-MoWO 3−x ), where γ-CD improves surface functionality and induces abundant structural defects. The γ-MoWO 3−x exhibits a 2.9-fold higher surface area and a more negatively charged surface (–27.25 to − 43.02 mV) due to γ-CD–derived hydroxyl groups. Acting as both an in situ reducing agent and defect-inducing molecule, γ-CD generates rich defective oxygen species and partially amorphizes the metal-oxide lattice, effectively tuning the band structure. As a result, γ-MoWO 3−x shows a 3.09-fold enhancement in adsorption–photocatalytic degradation of methylene blue, achieving > 98% removal within 40 min under 1-sun irradiation. Mechanistic studies reveal hole-dominant oxidation pathways. Nanosecond transient absorption spectroscopy Indicates that γ-MoWO 3−x accumulates more photogenerated holes and exhibits a larger proportion of fast hole-decay components, suggesting a higher population of surface-accessible holes that can promote oxidation reactivity. Photoluminescence quenching and electrochemical impedance spectroscopy further indicate suppressed carrier recombination and improved charge mobility. Overall, this work presents a simple and scalable cyclic-oligosaccharide-mediated approach for simultaneous defect and interface engineering, providing valuable design principles for next-generation photocatalysts.