Tuning Hydrophilicity of Aluminum MOFs by a Mixed‐Linker Strategy for Enhanced Performance in Water Adsorption‐Driven Heat Allocation Application

Abstract

Abstract Water adsorption‐driven heat transfer (AHT) technology has emerged as a promising solution to address crisis of the global energy consumption and environmental pollution of current heating and cooling processes. Hydrophilicity of water adsorbents plays a decisive role in these applications. This work reports an easy, green, and inexpensive approach to tuning the hydrophilicity of metal–organic frameworks (MOFs) by incorporating mixed linkers, isophthalic acid (IPA), and 3,5‐pyridinedicarboxylic acid (PYDC), with various ratios in a series of Al−xIPA‐(100−x)PYDC (x: feeding ratio of IPA) MOFs. The designed mixed‐linkers MOFs show a variation of hydrophilicity along the fraction of the linkers. Representative compounds with a proportional mixed linker ratio denoted as KMF‐2, exhibit an S‐shaped isotherm, an excellent coefficient of performance of 0.75 (cooling) and 1.66 (heating) achieved with low driving temperature below 70 °C which offers capability to employ solar or industrial waste heat, remarkable volumetric specific energy capacity (235 kWh m−3) and heat‐storage capacity (330 kWh m−3). The superiority of KMF‐2 to IPA or PYDC‐containing single‐linker MOFs (CAU‐10‐H and CAU‐10pydc, respectively) and most of benchmark adsorbents illustrate the effectiveness of the mixed‐linker strategy to design AHT adsorbents with promising performance.

Keywords

• low costs
• metal–organic frameworks
• mixed‐linkers
• tuning hydrophilicity
• water adsorption‐driven heat allocations