Shaping Water Adsorption and Desorption in Multivariate Metal–Organic Frameworks for Optimized Ultralow‐Temperature‐Driven Refrigeration

Abstract

ABSTRACT Ultralow‐temperature‐driven water‐sorption refrigeration provides an energy‐saving and eco‐friendly solution to realize near‐zero‐carbon cooling applications. Current water sorbents mainly focused on improving low‐pressure water uptakes for boosting cooling efficiency, while often hindered by cooperatively increasing desorption energy to show the opposite effect. Herein, we report a strategy of finely shaping water adsorption and desorption properties simultaneously in multivariate MOFs to maximize cooling efficiency. With broadly regulating the ratio of hydrophobic and hydrophilic linkers within UiO‐66, a series of multivariate MOFs [UiO‐66‐(BDC) x (PzDC) 1‐x ] were designed and synthesized, featuring a high tunability on both water uptake at P/P 0 = 0.2 and desorption energy. These high manipulations allow us to realize the optimal UiO‐66‐(BDC) 0.4 (PzDC) 0.6 with the most balance between water adsorption and desorption, as proven by its high water uptake of 0.4 g g −1 at P/P 0 = 0.2 and low desorption temperature down to 63°C for 90% desorption ratio. This maximizes its coefficient of performance (0.86) and working capacity (0.18 g g −1 ) for refrig‐2 applications achieved by an ultralow driving temperature of 63°C, outperforming the previously benchmark MIP‐200 (0.69 and 0.12 g g −1 ) and EMM‐8 (0.85 and 0.16 g g −1 ). The water‐sorption regulatory mechanisms were systematically elucidated by water‐loaded crystal structures.