A\nDirect Current Self-Sustained Moisture-Electric\nGenerator with 1<i>D</i>/2D Hierarchical Nanostructure for\nContinuous Operation of Off-Grid Electronics

Ubiquitous\nmoisture is a colossal reservoir of clean energy, and\nthe emergence of moisture-electric generators (MEGs) is expected to\nprovide direct power support for off-grid electronic devices anytime\nand anywhere. However, most MEGs rely on auxiliary energy storage\ndevices and rectifier circuits to drive small electronic devices,\nwhich hinder scalability and widespread deployment, and the development\nof direct current (DC) MEGs with high power output that can directly\ndrive off-grid electronic devices is highly promising but challenging.\nHerein, a self-sustained moisture-electric generator (SMEG) with a\nhierarchical nanostructure based on one-dimensional (1D) negatively\ncharged nanofibers and two-dimensional (2D) conductive nanosheets\nwas demonstrated to generate continuous DC electricity from atmospheric\nhumidity. Sulfation of bacterial cellulose nanofibers lowers the surface\npotential and increases the surface charge energy, and reduced graphene\noxide (rGO) provides a conduction pathway for electrons. The hierarchical\nnanostructures constructed by the combination of 1D nanofibers and\n2D nanosheets endow the SMEG with self-sustained moisture gradients\nand structural anisotropy, which force the generation of a pseudocurrent.\nThis combination also constructs microcapacitors that further enhance\nthe moisture-electric power output. The SMEG can generate a continuous\nvoltage in excess of 0.54 V for over 2160 h, with a power density\nof about 822 μW cm<sup>–3</sup>, demonstrating excellent\noperational durability. This research provides a feasible solution\nfor the development of sustainable, versatile, and efficient power\nsupplies for off-grid self-powered devices.