Nanoscale Laser Metallurgy and Patterning in Air Using MOFs

Abstract

We report metallurgy on the nanoscale to generate metal nanoparticles and their simultaneous patterning in a single step. This is achieved by the self-reduction of porous metal-organic framework crystals using nanosecond pulsed laser irradiation. Metal nanoparticles of Fe, Co, Ni, Cu, Zn, Cd, In, Bi, and Pb with uniform sizes (controllable between 3 to 200 nm) and gaps (as narrow as 2 nm) are produced by nine different metal-organic frameworks, where atomically dispersed non-noble metal ions are reduced and gathered across the pores. The instant light absorption and cooling at local positions by a laser allows for precise and efficient patterning of metal nanoparticles. This new method is suitable for device fabrication at a speed of 15 mm² s^-1 on glass, consuming only 1.5 W of power. A large variety of metal nanoparticle three-dimensional architectures are demonstrated, among which one architecture exhibits an enhanced plasmonic effect homogeneously across the entire pattern for the detection of molecules at an extremely low concentration (10^-12 M). These architectures are extremely stable under air and humidity during production, use, and storage, without altering the oxidation state, for 6 months.