Multifunctional Halloysite-Glutathione Nanocomposite for Solar CO2 Conversion and Pollutant Sensing

This study presents a highly sustainable nanocomposite platform for dual applications in both photocatalysis and sensing. The nanomaterial is synthesized via a green process using natural, readily available components, including halloysite nanotubes (HNTs), glutathione (GSH), and xanthopterin, utilizing copper ions (Cu¹⁺) as the catalytically active species. The synthesis, which exclusively uses green solvents like tetrahydropyran (THP) and water, involves functionalizing HNTs with (3-aminopropyl)-triethoxysilane (APTES), followed by the attachment of GSH as a chelating agent for Cu¹⁺. Finally, xanthopterin is loaded to act as a light-harvesting antenna. Fourier-transform infrared (FT-IR) spectroscopy and thermogravimetric analysis (TGA) confirmed the successful functionalization and composition. Scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) analysis validated the material's morphology and elemental composition. The resulting nanocomposite, HNT-NH₂-GSH-Cu¹⁺-X, demonstrated a remarkable synergistic effect, achieving a CO₂ conversion of 42.2% and a high (86.1%) CH₄ selectivity. Furthermore, the HNT-GSH-Cu²⁺ nanocomposite exhibited excellent electrochemical sensing capabilities for bisphenol A, with a low limit of detection (LOD) of 0.022 μM and a high sensitivity of 5.098 μA μM^-1·cm^-2. The work successfully demonstrates the creation of a sustainable, multifunctional nanomaterial that addresses critical environmental challenges by combining efficient solar fuel production with highly sensitive pollutant detection.