Enhanced proton conductivity from phytic acid-intercalated three-dimensional graphene oxide†

Despite graphene oxide (GO) and its derivatives showing potential as a proton conductor, the practical implications of GO-based membranes require further optimization of their proton conductivity. Herein, we report the improved proton-conducting properties of phytic acid intercalated three-dimensional graphene oxide (Phy-3DGO). The Phy-3DGO was prepared using a freeze-drying process. Experimental results prove enhanced proton conductivity with a magnitude of 2.45 × 10⁻¹ S cm⁻¹ at 65 °C and 90% RH in the out-of-plane direction compared to 3.21 × 10⁻³ S cm⁻¹ for 3DGO under similar experimental conditions. The low activation energy value of 0.26 eV for Phy-3DGO indicates the proton conduction through the Grotthuss mechanism. In the single-cell performance test, a maximum current density of 1210 mA cm⁻² and a maximum power density (MPD) of 248.2 mW cm⁻² were achieved using a 170 μm-thick Phy-3DGO film, compared to an MPD of 98.1 mW cm⁻² for 3DGO. These findings highlight the synergistic effects of graphene oxide and phytic acid in improving the interlayer distance and water retention, resulting in improved proton transport pathways. The study offers valuable insights into developing sustainable and efficient energy storage systems.