Droplet-Assisted Synthesis of Nanostructured Copper Microparticles with Enhanced Plasmonic Photocatalytic Performance

Plasmonic photocatalysts can catalyze chemical reactions using visible and infrared light, but their widespread adoption is hindered by the limited availability of noble plasmonic metals and the challenges associated with engineering plasmonic nanostructures in large quantities. To address these challenges, a method is developed for rapidly synthesizing an efficient plasmonic photocatalyst derived from an earth-abundant metal: copper. The widely utilized industrial technique of spray-drying is used for one-step synthesis of plasmonic copper microparticles (Cu MPs). The reduction and self-assembly of copper nanocrystals within evaporating microdroplets result in the formation of a unique morphology, exhibiting broad surface plasmon resonance absorption. Upon comparing the plasmonic properties of these spray-dried Cu MPs with commercially available copper nanoparticles (Cu NPs), it is observed that Cu MPs exhibited greater efficiency in the photocatalytic conversion of p-nitrothiophenol (p-NTP) to p,p′-dimercaptoazobenzene (p,p′-DMAB). Furthermore, Cu MPs demonstrate superior photocatalytic properties by catalyzing the reaction over a broader wavelength range compared to Cu NPs.