Application of nanosecond laser to a direct and rapid growth of Cu-BTC metal-organic framework thin films on copper substrate

Significant research efforts are being devoted to achieve metal-organic framework (MOF) thin films with tailored film thickness and high stability on solid substrates. We demonstrate the successful synthesis of uniform Cu-BTC films directly on a copper metal substrate, using rapid and efficient heat treatment assisted by a nanosecond laser. An oxidized copper substrate with an organic ligand is irradiated by the second harmonic of Nd³⁺:Y₃Al₅O₁₂ laser (532 nm), thereby forming Cu-BTC thin films through the photothermal process. The temperature of the laser-irradiated surface was estimated using COMSOL Multiphysics, aiding the optimization of the laser energy density for Cu-BTC crystal growth. The prepared Cu-BTC films exhibit a high surface area (985 m²/g) at 30 mJ/cm², with a peak surface temperature of ∼364 K. Notably, 3000 laser shots generate Cu-BTC films with a thickness of 10 µm. Thus, the study offers a novel fabrication method for a design strategy, involving the rapid growth (∼ 2 min) of MOF thin films on metal substrates.