Synergistic Coupling of Tribovoltaic and Moisture-Enabled Electricity Generation in Layered-Double Hydroxides

Ubiquitous energy harvesting technologies require new types of renewable, sustainable, and clean energy to solve the problems of fossil fuels. Although various nanogenerators have been developed over the last decade, low current density, requirements for complicated management circuits, generation of direct current (DC) outputs, and significant performance degradation under humid atmospheres have been problems limiting practical applications. This paper reports that the tribovoltaic and moisture-enabled electricity generation effects can be achieved in a layered double hydroxide (LDH) by applying a metal brushing mode. The ZnAl-LDH shows enhanced tribovoltaic nanogenerator (TVNG) performance even in a high-humidity environment coupled with the moisture-enabled electricity generated by the concentration gradient of a water molecule through the interlamellar structures of the LDHs. The spontaneous dissociation of water in the interior of LDHs removes the hole generated by the tribovoltaic effect, allowing high efficiency of an output voltage of 693.38 mV and current density of 65.48 mA m⁻² even under low-applied force (≈3.5 mN) at relative humidity 80%. The proposed TVNG provides a proof of concept for an all-in-one device consisting of a generator and capacitor because the LDH reveals a spontaneous charging performance similar to that of a capacitor.