HKUST-1 coatings on laser-microperforated brass supports for water adsorption

Abstract

This work describes the preparation of HKUST-1 layers on brass supports by a thermal gradient approach. Supports were perforated using laser irradiation to create 30–50 μm microholes. Perforation improved the adhesion and loading of the MOF. The microhole environment generated during the laser treatment led to well-anchored coatings. Two distinct samples were synthesized with the reaction temperature (100 and 150 °C) as the main difference. A continuous HKUST-1 coating was only achieved with the higher temperature of 150 °C. However, the microholes were totally filled with crystals in both samples reaching weight fractions of crystallized material of 2.4 and 6.6 wt%. PXRD and N₂ physisorption studies confirmed the formation of HKUST-1 crystals with high quality (S_BET = 1105 m² g⁻¹). Water adsorption was performed on both samples, showing the main sorption event below a relative pressure of 0.4 and obtaining uptakes (0.48 and 0.45 g g⁻¹ at 293 K and p/p₀ = 0.9) among the reported values for HKUST-1 powder. The HKUST-1 properties and the enhanced MOF–support interaction make these coatings candidates for use in gas storage and separation, sensing and water-based adsorption applications, such as chillers or heat pumps.