In Situ Synthesis of Highly Dispersed AuNPs – Hydrogel Composites via Plasma for Enhanced Catalytic Activity

Abstract Gold nanoparticles (AuNPs) were effectively synthesized and highly dispersed within a hydrogel composite by glow discharge plasma reduction. The hydrogel structure was successfully preserved due to the low temperature operation of plasma. The gold was reduced in situ within the hydrogel channels via electron reduction, and the uniformly distributed metal particles benefited from the confinement effect. The particle size could be controlled by adjusting precursor concentration and the type of hydrogel used. Hydrogels based on gelatin were found to increase the interaction between gold and the hydrogel. This enhancement was attributed to the Coulomb force arising from the isoelectric point and surface plasmon resonance (SPR) of the hydrogel composites, which promoted the dispersion of AuNPs. The different treatment procedures confirmed that SPR induced changes in the hydrogel surface, which played a key role in the dispersion and anchoring of gold during the reduction process. As a result, the AuNP‐doped hydrogel composite exhibited significantly enhanced catalytic activity in the degradation of methylene blue, with AuNP‐Gel‐1 achieving complete MB degradation in just 12 seconds.