Self-assembled two-dimensional metal–organic framework membranes as nanofluidic osmotic power generators

Abstract

Metal–organic framework (MOF) membranes with high ion selectivity and permeation rates have emerged as excellent platforms for high-performance osmotic energy harvesting. However, only a few MOFs have been successfully fabricated as selective ion transport membranes for osmotic energy generation due to the challenge of high-quality MOF membrane fabrication. In this work, 2D ZnTCPP nanosheets were synthesized to construct ion-selective membranes for osmotic energy harvesting. The ZnTCCP nanofluidic membranes have adequate pores, which are in the ZnTCPP nanosheets and between the nanosheets, enabling a power density of 2.85 W m⁻² with a cation selectivity of up to 0.9 and an energy conversion efficiency of 30% under 0.5 M/0.01 M KCl concentration gradient. As the thickness of the membrane decreases to 4 μm, the device power density increases to 3.01 W m⁻². The membrane energy harvesting performance can be further improved by increasing the temperature and pH of electrolyte solutions. This work highlights the potential of 2D MOF nanosheets for high-performance osmotic energy harvesting.