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 next-generation energy technology. The ubiquitous air offers an alternative, but existing carbon-based moisture-electric generators can only generate desultory or insufficient power under air, owing to the absence of sustaining and effective energy harvesting and conversion architecture and mechanism. Here an eco-friendly and direct solid molding strategy was applied to rapidly fabricate heterogeneous oxo-graphene (H-mrGO) assembly. Inspired by root and trunk in natural vascular plants, rational fabrication of hierarchical porous structure immensely enhances spontaneous absorption of water molecules from air, which further induces rapid proton diffusion because of self-maintained and huge concentration difference. A single H-mrGO device can spontaneously produce an ultrahigh voltage of ∼1.39 V under air (RH ≈ 99%) and a high voltage of ∼1.2 V at low humidity (∼30%) is obtained, accompanied by a power density of ∼1.1 W/m2. Meanwhile, it realizes a sustaining power output for external resistance over 40,000 s with good stability. Connecting several H-mrGO devices linearly magnifies voltage up to 10 V and obtains a wearable device, which can directly power different electronics without additional transverters. This work demonstrates the feasibility of a sustaining moisture-electric energy-harvesting strategy that loosens rigorous requirements of location or environmental conditions.