Plasmonic silver nanoparticles promoted sugar conversion to 5-hydroxy-methylfurfural over catalysts of immobilised metal ions

Plasmonic photocatalysis has attracted significant attention but not been applied to acid-catalysed reactions. Here we report that visible-light irradiation of silver nanoparticles (AgNPs) significantly promotes Lewis acidcatalysis by several immobilised metal ions to dehydrate sugars, producing 5-hydroxymethylfurfural (HMF) in good yields at moderate temperatures. In one example, we achieved a 68 % yield of HMF for the conversion of Dglucose using immobilised Cr3+ ions and AgNPs under visible-light irradiation. The turnover number achieved in the presence of AgNPs is 13.4 times higher than in the absence of AgNPs. We propose a mechanism whereby sugar molecules coordinate to the metal ions, and light absorption by these metal complexes causes electron density distribution shift to the ions, thereby boosting the catalytic activity. Surface plasmon resonance by the AgNPs amplifies incident light to high intensities, considerably promoting catalytic activity. This plasmonenhanced acid catalysis performance defines a new paradigm and expands photocatalysis applications.

Automated summary

Plasmonic photocatalysis using silver nanoparticles (AgNPs) has been shown to significantly enhance Lewis acid catalysis for dehydrating sugars to produce 5-hydroxymethylfurfural (HMF) under visible light irradiation. The presence of AgNPs amplifies incident light to high intensities and promotes catalytic activity, leading to a new paradigm in photocatalysis applications.