Evaporation-induced energy harvesting via a Zn-imidazole intercalated graphene oxide nanogenerator

Abstract

Among green and zero-emission energy harvesting approaches, water evaporation-induced generators (WEIGs) are one of the most environmentally friendly techniques due to their ability to convert atmospheric thermal energy into electricity through the evaporation of water passing through ion-selective nanofluidic channels. Membranes having charged nanofluidic channels, with their nanocapillary effects and selective ion transport capabilities, have emerged as effective platforms for this purpose. Herein, we report on the fabrication of a Zn-imidazole complex (ZnIm) intercalated graphene oxide (GO) membrane and its application in WEIG devices. The GO-ZnIm membrane exhibits an inplane selective cation transport behavior owing to its negatively charged nanofluidic channels (cation (K+) selectivity: 0.91). The GO-ZnIm-based WEIG device generates a continuous voltage of 0.75 V and a current of 0.4 μA in deionized water, which marginally decreases to 0.6 V and 0.55 V in river and saline water, respectively, demonstrating the membrane's energy harvesting potential in real systems. The WEIG exhibits a long-term stable maximum power density of 157.5 μW cm−3. Furthermore, the voltage output increases linearly when multiple devices are connected in series, highlighting the practical scalability of the system for real-world applications. © 2025 Elsevier B.V.