A green and sustainable water evaporation-induced electricity generator with woody biochar

The generation of electricity through the natural process of water evaporation has emerged as a promising method of energy conversion. However, many advanced generators utilizing this technique, known as water evaporation-induced electric generators (WEIGs), feature a complicated fabrication process and lack output stability, hindering their practical use in real-world applications. In this study, we present a facile fabrication of an efficient WEIG based on woody biochar (WBC). WBC was prepared from lignocellulosic feedstocks (LCFs) in a tube furnace and then mixed with ethyl cellulose (EC) and ethanol to acquire a homogeneous slurry. WEIG was then fabricated in air pyrolysis after casting the slurry with a silicone pad. A key advantage of this material is the presence of hydrophilic functional groups in WBC, which allows for constant, sustainable generation of electricity from water without the need for additional hydrophilic treatments. For the first time, we thoroughly examined the formation process of WBC and evaluated the impact of WBC derived from three different components of LCFs on electricity generation. Additionally, we analyzed the electricity generation mechanism of WBC-based WEIG and the influence of botanical origin, particle size, and carbonization temperature of WBC on the electrical properties. Our findings indicate that lignin-rich WBC is particularly well-suited for use in WEIGs, suggesting the potential for widespread adoption of LCFs in hydro-voltaic power generation. Under ambient conditions, a single WEIG device was able to achieve a maximum open-circuit voltage (VOC) of 0.42 V and a short-circuit current (ISC) of 528 nA. Furthermore, when multiple devices were connected in series, a VOC of 7 V was attained, sufficient to power small commercial electronics. The implementation of these findings has the potential to pave the way for the development of green energy generators through the utilization of water evaporation on WBC.