Fluorine-incorporated Graphene Oxide for hydrovoltaic power generation: improving proton migration and storage capacity

As global demand for electricity increases, the adoption of low-emission energy strategies becomes imperative for effective electricity generation. The abundance of unutilized low-grade energy in our environment has led to the development and implementation of hydrovoltaics (HVs) as a viable solution. In this article, we present a device using fluorinated graphene oxide (GO) and polyethylene glycol to efficiently harvest energy using HVs. By incorporating fluorine, hydrophilic GO became partially hydrophobic. Fluorine-incorporated GO with enhanced surface charge and polyethylene glycol was added to generate hydro-polymeric network that facilitates water transport. The device fabricated using a centimeter-sized silicone ice tray with top and bottom electrodes loaded with 40 mg of fluorinated GO, generates a streaming potential and current when exposed to water. A mere 20 µL of water on the top electrode yielded an open circuit voltage in a range of 250 mV, a short circuit current in a range of 100 µA, with an output power of 0.625 mW/g (11.16 µW/cm2). The same device yields a better power density of 1.33 mW/g (23.8 µW/cm2) under half-sun solar illumination and power density of 0.45 mW/g (8.5 µW/cm2) after 40 days. We validated the streaming potential and current of HV devices by comparing our experimental data with theoretical electrokinetic models of hydrodynamic flow. Furthermore, we explored the energy storage capacity of the same material, resulted in a significant increase in active sites, leading to a capacitance of 350 F/g with improved cyclic stability. The HV cell was also used to charge a coin cell made from the same material, presenting a novel approach for integrated systems. This article highlights the multifunctional applications of fluorinated GO, offering a promising avenue for sustainable power generation.