Bioinspired Heterogeneous and Hierarchical Porous Structure of Oxo-Graphene Assembly for Spontaneous Energy Harvesting from Air

Abstract

Environmentally adaptive energy harvesting without additional stimuli is glamorous for the next-generation energy technology. The ubiquitous air provides an alternative, but existed carbon-based moisture-electric generators can only generate desultory or insufficient power under air, owing to the absence of a sustained and large energy harvesting and conversion structure and mechanism. Here an eco-friendly and direct solid molding strategy was developed to rapidly fabricate the heterogeneous oxo-graphene (H-mrGO) assembly. Inspired by the root and trunk in natural vascular plants, the rational fabrication of hierarchical porous structure immensely enhances the spontaneous absorption of water molecules from air, which further induces the rapid proton diffusion because of the self-maintained and huge concentration difference. A single H-mrGO device can spontaneously produce an ultrahigh voltage of ~1.39V under air (RH ≈ 99%) and a high voltage of ~1.2V at the low humidity (~30%) is even obtained, accompanied by a high power density of ~1.1W/m2. Meanwhile, it realizes a sustaining power output for external resistance over 40000s with good stability and recyclability. Connecting several H-mrGO units linearly magnifies voltage up to 10V and acquires a wearable device, which can directly power various electronics without additional transverters. This work demonstrates the feasibility of a sustaining moisture-based energy-harvesting strategy that loosens the rigorous requirements of location or environmental conditions.

Keywords: moisture-based energy harvesting, solid molding, heterogeneous oxo-graphene assembly, hierarchical porous structure, sustaining power