Green synthesis and characterization of SnO₂, CuO, Fe₂O₃/activated carbon nanocomposites and their application in electrochemical hydrogen storage

The goal of this study is to produce environmentally friendly nanomaterials that have a high hydrogen storage capacity. The researchers in this study used inexpensive natural bitumen to produce activated carbon (substratum) and a green solution synthesis combustion method to produce CuO, Fe₂O₃, and SnO₂ nanoparticles using a Mint extract as the source material. Metal oxides such as CuO, Fe₂O₃ and SnO₂ are used to increase hydrogen storage capacity and Columbic efficiency. AC and AC/SnO₂, AC/CuO, and AC/Fe₂O₃ nanocomposites have been confirmed via XRD (X-ray diffraction), TEM (transmission electron microscopy), EDX (energy-dispersive X-rays), FT-IR (fourier transform infrared), scanning electron microscope (SEM), and adsorption and desorption analysis of N₂ (BET). In terms of discharge capacity, AC/CuO, AC/Fe₂O₃, and AC/SnO₂ display respective capacities of 2250, 2500, and 3600 mAh/g after 20 cycles, respectively. Of all the sample materials, the AC/SnO₂ nanocomposite with the highest hydrogen storage capacity has the lowest Columbic efficiency. This implies that a sample with 54% Columbic efficiency, such as AC/CuO nanocomposite, is a more suitable specimen.