One-step fabrication of Cu nanoparticles on silicate glass substrates for surface plasmonic sensors

Cu nanopartides (NPs) have attracted considerable attention as a substitute for noble metals, such as Au and Pt, due to their unique surface plasmon resonance (SPR) properties, natural abundance, and low fabrication cost. We succeeded in one-step preparation of Cu NPs with a uniform size on glass surface by heating Cu2+ ions containing Na2O-Al2O3-SiO2 glass in hydrogen atmosphere. The formation of Cu NPs was confirmed using scanning and transmission electron microscopies, small-angle X-ray scattering, and visible and infrared absorption spectroscopies. Heat treatment in a hydrogen environment facilitated the diffusion of hydrogen molecules into the glass to form Cu atoms and Al OH bonds. The Cu atoms migrated through gaps formed by Al OH toward the surface, where they combined to form Cu NPs. The optical spectra of showed sharp and intense SPR bands at a peak wavelength of 580 nm, indicating the homogeneous distribution of uniformly sized Cu NPs on the glass surface without aggregation. The obtained samples exhibited good sensing performance due to the strong SPR properties. Further advantage of our method was that Cu nanoparticles can be repeatedly formed by heating under H-2 gas after removing the previously formed particles.