Protector-free, non-plasmonic silver quantum clusters by femtosecond pulse laser irradiation: in situ binding on nanocellulose filaments for improved catalytic activity and cycling performance.

This study introduces a new, facile method to synthesize silver clusters from aqueous silver ion solution by using high intensity femtosecond pulse laser irradiation. The particles obtained in the absence of reducing or capping agents are 1-17 nm in size and presented quantum properties, as characterized by fluorescence, but did not exhibit plasmon signals, which is not a common characteristic of conventional silver nanoparticles. In a further development, small silver quantum clusters (∼1 nm) were bound in situ to wet-spun filaments of cellulose nanofibrils by pulsed laser irradiation. The obtained hybrid filaments as well as free silver quantum clusters revealed a catalytic activity remarkably higher than that of free gold quantum clusters; moreover, the hybrid filaments were found to show improved stability and cycling performance for silver-based catalysis. The present results indicate the potential of femtosecond laser irradiation to generate clusters as well as hybrid systems with excellent performance and reactivity.