β-Cyclodextrin and reduced graphene oxide loaded Ag–TiO₂ composites for enhanced photocatalytic oxidation of urea under sunlight

Urea oxidation is important to increase agricultural growth, which can meet food requirements across the world. It is pivotal for converting nitrogen to nitrate that is usable by crops, thus preventing nitrogen loss to the atmosphere. This study focuses on improving the photodegradation efficiency of TiO₂ by incorporating β-CD (beta-cyclodextrin), RGO (reduced graphene oxide), and Ag to enhance nitrate conversion. FT-IR, DRS, PL, EDX, XRD, XPS, HR-TEM DLS, and FESEM were conducted to characterize these materials. Among all the catalysts, the quaternary composite, β-CD/Ag-TiO₂/RGO, exhibited superior performance, achieving an 86.2% degradation efficiency with a 27.8% nitrate yield under sunlight irradiation within 150 min of reaction time. Several factors contribute to the enhanced photoactivity of β-CD/Ag-TiO₂/RGO, including the high surface area and absorptive power of β-CD, the large electronic mobility of RGO, and the localized surface plasmonic resonance effect of Ag, extending the catalyst's response to visible light. An intriguing aspect of this study is the encapsulation of gaseous nitrogen into the hydrophobic interior cavity of β-CD, contributing to the enhancement of urea oxidation. These findings can be very substantial for both agriculturists and chemists, providing valuable insights into designing novel photocatalysts for improved urea oxidation, thereby enhancing agricultural productivity.