Confinement in metal-organic frameworks as a route to harnessing liquid barocalorics in the solid-state

TL;DR

This study demonstrates that confining liquid barocaloric materials within metal-organic frameworks enables solid-state thermal management with enhanced control, potentially replacing environmentally harmful fluids in cooling technologies.

Contribution

The paper introduces a novel method of embedding liquid barocaloric materials in MOFs to retain and control colossal barocaloric effects in solid-state systems.

Findings

Colossal barocaloric effects are preserved in MOF-confined solid-liquid systems.

Active control over thermal response is achieved through interactions with the MOF surface.

The approach offers a leak-free, recyclable alternative to traditional liquid BC materials.

Abstract

Barocaloric (BC) effects at liquid-vapor transitions in hydrofluorocarbons drive most commercial technologies used for heating and cooling in the heating, ventilation and air-conditioning sector. However, these fluids suffer from huge global warming potential and alternative gases are less efficient, toxic or flammable. Solid-solid and solid-liquid BC materials have zero global warming potential and could even improve on current device efficiencies. Whilst solid-liquid BCs typically outperform solid-solid BCs, the latter are advantageous as they avoid leaks and present easier handling and recyclability thus facilitating waste management. Here we confine the solid-liquid BC stearic acid inside the nanopores of a functionalised metal-organic framework (MOF) and demonstrate that the colossal BC properties are retained in a solid-state material. Moreover, the enhanced interactions between the pore surface and the BC material allow a level of active control over the thermal response, as opposed to passive encapsulation. Our results open novel avenues to exploit and tune colossal BC effects in a wide range of combinations of solid-liquid BC materials embedded within functionalized MOFs, without the associated engineering drawbacks.