Pt/SnO2/Sb2O4 nanoparticle catalyst embedded in multi-walled carbon nanotubes as an active material for electrochemical hydrogen storage application

Hydrogen storage and safe transport are the most important factors for hydrogen energy applications. Hydrogen has the necessary potential to provide clean fuel for heating and transportation because its only combustion product is pure water. Hydrogen is identified as one of the most renewable energy sources. The electrochemical method with high energy conversion efficiency, through absorption/desorption mechanisms, is considered an appropriate strategy to achieve hydrogen storage. Hence, we propose a hydrogen energy storage system based on efficient electrode materials and the electrochemical method. For achieving high-efficiency hydrogen storage, a Pt/SnO₂/Sb₂O₄ nanoparticle catalyst embedded in multi-walled carbon nanotubes (MWCNTs) was synthesized as an active material via a facile polyol method. The catalyst was characterized using different techniques to determine its crystal structure, surface morphology, elemental composition and porosity. Furthermore, the electrochemical hydrogen storage abilities and specific capacitance of the as-prepared nanocomposite were assessed in alkaline media through chronopotentiometry and cyclic voltammetry analysis. XRD studies exhibit that the average crystallite size of the Pt/SnO₂/Sb₂O₄ nanoparticle catalyst is estimated to be around 7.5 nm. Moreover, BET measurement shows a specific surface area, pore volume and pore diameter of 137.89 m² g⁻¹, 0.3379 cm³ g⁻¹ and 9.8 nm, respectively, for the Pt/SnO₂/Sb₂O₄/MWCNT nanocomposite. Electrochemical results indicate that the incorporation of the Pt/SnO₂/Sb₂O₄ nanoparticle catalyst into MWCNTs resulted in excellent cycling stability and a high degree of electrochemical reversibility, positioning the catalyst as a promising active material for use in electrochemical hydrogen storage. The maximum discharge capacity of the Pt/SnO₂/Sb₂O₄/MWCNT nanocomposite was calculated to be 3480 mA h g⁻¹ after 12 cycles. The higher and excellent discharge capacity of the nanocomposite can be partially ascribed to its higher porosity, large specific surface area and small size.