Empowering CO₂ Eco‐Refrigeration With Colossal Breathing‐Caloric‐Like Effects in MOF‐508b

Abstract

Today, ≈20% of the electric consumption is devoted to refrigeration; while, ≈50% of the final energy is dedicated to heating applications. In this scenario, many cooling devices and heat‐pumps are transitioning toward the use of CO2 as an eco‐friendly refrigerant, favoring carbon circular economy. Nevertheless, CO2 still has some limitations, such as large operating pressures (70–150 bar) and a critical point at 31 °C, which compromises efficiency and increases technological complexity. Very recently, an innovative breathing‐caloric mechanism in the MIL‐53(Al) compound is reported, which implies gas adsorption under CO2 pressurization boosted by structural transitions and which overcomes the limitations of stand‐alone CO2. Here, the breathing‐caloric‐like effects of MOF‐508b are reported, surpassing by 40% those of MIL‐53(Al). Moreover, the first thermometry device operating at room temperature and under the application of only 26 bar of CO2 is presented. Under those conditions, this material presents values of ΔT ≈ 30 K, reaching heating temperatures of 56 °C and cooling temperatures of −10 °C, which are already useful for space heating, air‐conditioning, food refrigeration, and freezing applications.