Anion-Selective Layered Double Hydroxide Composites-Based Osmotic Energy Conversion for Real-Time Nutrient Solution Detection.

Nanofluidic channels based on 2D nanomaterials are promising to harvest osmotic energy for their high ion selectivity and osmotic conductivity. However, anion-selective nanofluidic channels are rare and chemical modification is necessary through fabrication. Here, a naturally anion-selective composite membrane is reported, that is, NiAl-Layered double hydroxide (LDH) coated anodic aluminum oxide (LDH@AAO), using a simple precipitant-free in situ growth technique. Positively charged LDH plates growing in channels of AAO function as screening layers for anions. Both experiments and theoretical simulations are enforced to certify the vital role of LDH growth in ion distribution and salinity gradient energy conversion. The composite membrane achieves high output performance and long-term stability. Furthermore, novel applications of nanofluidic channels are explored in hydroponic production and design a real-time detecting system based on LDH@AAO composite membranes for nutrient solution. This work provides insights into naturally anion-selective nanofluidic channels for osmotic energy harvesting and broadens the application in agricultural information sensing.