Empowering CO 2 Eco-Refrigeration with Colossal Breathing-Caloric-Like Effects in MOF-508b.

Today, around 20% of the electric consumption is devoted to refrigeration, while around 50% of the final energy is dedicated to heating applications. In this scenario, many cooling devices and heat-pumps are transitioning towards the use of CO 2 as an eco-friendly refrigerant, favouring carbon circular economy. Nevertheless, CO 2 still has some limitations, such as large operating pressures (70-150 bar) and a critical point at 31 °C, which compromise efficiency and increase technological complexity. Very recently, we have reported an innovative breathing-caloric mechanism in the MIL-53(Al) compound, which implies gas adsorption under CO 2 pressurization boosted by structural transitions, and which overcomes the limitations of stand-alone CO 2 . Here, we report the breathing-caloric-like effects of MOF-508b, surpassing by 40% those of MIL-53(Al). Moreover, we present the first thermometry device operating at room temperature and under the application of only 26 bar of CO 2 . Under those conditions, our 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. This article is protected by copyright. All rights reserved.