Emerging working pairs of MOF-ammonia for sustainable heat transformation and storage

Abstract

Heat transformation and storage based on the solid sorption principle, as a prospective sustainable and carbon-neutral technology, possesses significant potential for renewable energy utilization and carbon footprint reduction. However, the water and alcohols cannot adapt to critical conditions of low evaporation and high condensation temperatures, thus limiting the efficient utilization of thermal energy. This critical issue could be mitigated by engineering a transformative sorption working pair, known as a metal-organic framework (MOF)-ammonia working pair, which can reversibly convert solar-thermal energy to chemical energy and thermodynamic potential energy, enabled by the sorption and desorption processes. This perspective examines the feasibility and challenges of MOFs in saturated ammonia sorption for thermal energy utilization, such as refrigeration, ice making, heat pumps, and thermal energy storage. We discuss the evaluation and selection criteria for high-stability MOFs, the design of thermodynamic cycles, and performance assessments. Finally, this article also provides an ingenious insight into the potential applications of MOF-ammonia working pairs and proposes future research directions and solutions to advance the carbon neutrality vision.