Architecting Ultra-Robust Zr(IV) Metal-Organic Framework for Energy-Efficient Desiccant Air Conditioning

Air-conditioning systems, composed mainly of humidity control and heat reallocation units, play a pivotal role in upholding superior air quality and human well-being across diverse environments ranging from international space stations and pharmacies to granaries and cultural relic preservation sites, and to commercial and residential buildings. The adoption of sorbent water as the working pair and low-grade renewable or waste heat in adsorption-driven air-conditioning presents a state-of-the-art solution, notably for its energy efficiency and eco-friendliness vis-à-vis conventional electricity-driven vapor compression cycles. Here, we introduce a rational π-extension strategy to engineer an ultrarobust and highly porous zirconium metal-organic framework (Zr-MOF). This MOF sorbent showcases hysteresis-free S-shaped water sorption isotherms, characterized by a rapid ascent within the 40-60% relative humidity range with a working capacity of 0.63 g g^-1, thus facilitating intelligent indoor humidity regulation. Moreover, we demonstrate, for the first time, that this material with such distinctive isotherms can yield a 10 °C temperature lift between ambient and chiller output with a high cooling capacity of 336 kW h m^-3 per cycle, even at exceptionally low driving temperatures (below 50 °C), while also delivering a substantial coefficient of performance of 0.96. This material is amenable to scale-up and is chemically ultrastable that can endure strong acids and be cycled for at least 200 runs without compromising any of its capacity. These exceptional attributes signify the viability of this material as a pragmatic alternative for deployment in energy-efficient desiccant air-conditioning systems, particularly in hot and humid climatic regions.