Halloysite-kojic acid conjugate: A sustainable material for the photocatalytic CO2 reduction and fixation for cyclic carbonates production.

This study introduces a straightforward synthesis method for producing a hybrid material composed of halloysite and kojic acid, which catalyzes carbon dioxide (CO 2) conversion processes. Kojic acid, derived from malted rice fermentation, exhibits inherent chelating properties that facilitate the introduction of copper ions onto the material's surface. Copper ions, an economically viable alternative to noble metals, catalyze CO 2 conversion reactions effectively. The hybrid catalyst was evaluated for two distinct CO 2 conversion pathways: photocatalytic methane production under simulated sunlight and CO 2 fixation into cyclic carbonates via epoxide reactions. The hybrid material demonstrates remarkable catalytic activity under mild conditions, achieving high conversion efficiencies at 45 °C for methane production and 70 °C for carbonate fixation at atmospheric pressure. Conversion of 31 % and 89 % were achieved for the photocatalytic CO 2 reduction and the carbonate fixation, respectively. FT-IR spectra confirmed the functionalization of the material. Additionally, its organic/inorganic hybrid nature is complemented by excellent thermal stability, as studied by TGA. It enables repeated utilization, maintaining a 25 % catalytic activity for methane production and 70 % for carbonate fixation after the fourth reuse. This research highlights the potential of using naturally derived materials for sustainable CO 2 mitigation. [Display omitted] • Hybrid halloysite-kojic acid material efficiently catalyzes CO 2 conversion processes. • Copper ions offer a cost-effective alternative to other metals. • Converts CO 2 to methane under simulated sunlight at 45 °C and atmospheric pressure. • Fixes CO 2 into cyclic carbonates with epoxides at 70 °C. • Facile synthesis and excellent thermal stability enhance practical utility. [ABSTRACT FROM AUTHOR]