A metal-organic framework for efficient water-based ultra-low-temperature-driven cooling

Efficient use of energy for cooling applications is a very important and challenging field in science. Ultra-low temperature actuated (T_driving < 80 °C) adsorption-driven chillers (ADCs) with water as the cooling agent are one environmentally benign option. The nanoscale metal-organic framework [Al(OH)(C₆H₂O₄S)] denoted CAU-23 was discovered that possess favorable properties, including water adsorption capacity of 0.37 g_H2O/g_sorbent around p/p₀ = 0.3 and cycling stability of at least 5000 cycles. Most importantly the material has a driving temperature down to 60 °C, which allows for the exploitation of yet mostly unused temperature sources and a more efficient use of energy. These exceptional properties are due to its unique crystal structure, which was unequivocally elucidated by single crystal electron diffraction. Monte Carlo simulations were performed to reveal the water adsorption mechanism at the atomic level. With its green synthesis, CAU-23 is an ideal material to realize ultra-low temperature driven ADC devices.