High performance UiO-66 through microwave-assisted and Cr doping for adsorption heat storage applications

Abstract

The metal–organic framework UiO-66 is a promising water vapor adsorbent due to its stability and hydrophilicity. In this study, we systematically investigated the modulation of pore structure and water adsorption performance of UiO-66 through microwave-assisted synthesis and controlled Cr³⁺ doping. The results indicated that the crystalline integrity and thermal stability of the framework remained well-preserved after doping. The UiO-66 samples with Cr³⁺ addition have higher pore volume and specific surface area. When the mole ratio of Cr to Zr is 1.5, the micropore volume and BET specific surface area of MW-1.5Cr-UiO-66 are 15.1% and 19.8% higher than MW-UiO-66. This structural optimization resulted in superior adsorption performance, with the saturated water adsorption capacity of MW-1.5Cr-UiO-66 reaching 0.59 g g⁻¹. Furthermore, the water adsorption capacity of MW-1.5Cr-UiO-66 remained unchanged after 10 cycles. The coordinated modulation of pore architecture and surface chemistry through transition metal doping provides new insights for developing high-performance adsorbents in adsorption heat storage applications.