Nanoscale Laser Metallurgy and Patterning in Air Using MOFs

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.