Synthesis of zinc-silica quantum dots for high-efficiency photocatalytic applications

Colloidal quantum dots have attracted sustained interest for over four decades due to their size-dependent optical properties and broad applications in optoelectronics, imaging, and catalysis. Yet, scalable and eco-friendly solid-state synthesis remains a major challenge. Here, we report a novel multigrowth-catalyst (MG-C) approach for synthesizing multi-emission ZnO@SiO₂ quantum dots (Q-Dots) in powder form. The method harnesses droplet-induced ripple oscillations and zeta potential stabilization in aqueous NaCl to precisely control nucleation and growth. Compared with conventional sol–gel and bio-assisted ZnO photocatalysts, the resulting core–shell ZnO@SiO₂ Q-Dots show (i) multiple tunable emission peaks, (ii) improved charge-carrier separation via the silica shell, and (iii) superior photocatalytic efficiency, achieving 99 % dye removal under sunlight and 98.6 % of methylene blue under UV light within 30 min at low catalyst loading. The MG-C strategy is simple, scalable, and environmentally benign, offering a promising route to advanced nanomaterials with tailored optical and catalytic functions.