Supersonically sprayed gas- and water-sensing MIL-100(Fe) films

Highly uniform, mechanically stable, dense, and water-adsorbing MIL-100(Fe) films were fabricated via supersonic spraying, a rapid, high-throughput, and scalable method compatible with roll-to-roll processing. The film surface area (1667 m² g⁻¹) was comparable to that of the nanoparticles from which it was prepared (2009 m² g⁻¹), and was higher than previously reported values for MIL-100(Fe) films. The gas and water adsorption abilities of the film were tested by nitrogen physisorption and water adsorption at 30 °C. The supersonically sprayed film was mechanically resistant up to a critical scratching load of 1.84 N, higher than the critical scratchability loads of dip-coated or spin-coated films. In humidity-sensing applications, films that incorporated conductive Ag nanowires were highly responsive to environmental humidity, demonstrating applicability as water vapor sensors. The fabricated films were characterized by X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, and atomic force microscopy.