Green synthesis of zinc oxide/polymeric graphitic carbon nitride nanocomposites: boosting photocatalytic glucose-to-sorbitol conversion

Abstract

Nanotechnology is increasingly focused on developing non-toxic, sustainable photocatalysts sensitive to visible light. This study presents a simple, low-temperature biosynthesis method utilizing leaf extract from the Avicennia marina mangrove to produce zinc oxide/graphitic carbon nitride nanocomposites (ZnO/g-C₃N₄ NCs). These photocatalysts effectively convert glucose from corn starch after enzymatic hydrolysis into sorbitol and generate hydrogen under visible light. Comprehensive analyses of the optical, morphological, and structural properties of the synthesized nanocomposites were conducted. Photocatalytic testing under UV–Vis irradiation revealed a significant enhancement in hydrogen production and sorbitol yield (93%) compared to individual components. Additionally, the photocatalytic performance for degrading Acid Red 27 dye was evaluated. A novel room temperature, atmospheric pressure catalytic hydrogen transfer (CHT) method was developed for converting D-glucose to D-sorbitol using the ZnO/g-C₃N₄ photo-nanocatalyst in aqueous ethanol, eliminating the need for molecular hydrogen. The synergistic interaction between ZnO and g-C₃N₄ facilitates effective charge separation and transfer, enhancing redox processes and overall performance. This study demonstrates that ZnO/g-C₃N₄ NCs are promising photocatalysts for sustainable energy production and biomass conversion, outperforming existing methods and offering a green approach for efficient sorbitol production in mild conditions.