Spontaneous power generation from broad-humidity atmospheres through heterostructured F/O-bonded graphene monoliths

Abstract

Spontaneous energy-harvesting from the environment without external stimuli is a challenging task for clean and renewable power. However, existing carbon-based energy generators require the sequential gradient structure and can only produce a low and desultory power relying on the atmospheric moisture. Here we develop a direct dry-compression molding strategy to rapidly manufacture the heterostructured F/O-bonded graphene monolith (H-OGF) with two integrated parts of fluorinated oxidized graphene (FOG) and oxidized graphene (OG) for the first time. Fabricated H-OGF device spontaneously generates a voltage of ~1.25 V (the largest voltage reported for spontaneous carbon-based energy-harvesting devices) and it also achieves a continuous power output for external resistance over 40,000 s with good stability and recyclability. The initial energy input is originated from the transformation of moisture from the gaseous state in atmosphere to the agminated state in H-OGF. This promotes the H+ dissociation and the spontaneous formation of self-maintained and huge H+ concentration difference between FOG and OG layers, which works as the driving force for the continuous power production. Moreover, the introduced fluorine with the maximal electronegativity (3.98) accelerates the carboxyl’s ionization and further magnifies H+ concentration difference. Connecting several H-OGF devices proportionally amplifies voltage up to 10 V for powering electronics and obtains a wearable power supply. Our findings make H-OGF devices promising candidates for low-budget and self-sustaining energy systems as rigorous requirement of location or environmental conditions is loosened.