Synthesis and hydrogen storage application of innovated ternary-based NiFe2O4/Fe2O3/g-C3N4 nanocomposites by facile Pechini sol–gel method

Abstract

Nowadays, renewable and clean energy sources, such as hydrogen, play a key role in the development of societies. Hydrogen can be stored in various ways, like the electrochemical approach. Hydrogen stands out as a promising clean-burning fuel for future energy systems. However, its relatively low volumetric energy density at ambient conditions has made it challenging to optimize its storage and use effectively. To tackle the energy crisis, researchers have been focusing on developing advanced electrode materials with high capacity to address these limitations and improve hydrogen's practicality for energy production and consumption. This study illustrates the first effort to design and investigate the performance of ternary NiFe₂O₄/Fe₂O₃/g-C₃N₄ nanocomposite as an electrocatalyst for usage in electrochemical hydrogen storage applications. Ternary NiFe₂O₄/Fe₂O₃/g-C₃N₄ nanocomposites have been synthesized through the multiple-step method. Various techniques have been employed to characterize the resulting nanostructures, focusing on aspects such as their morphology, porosity, dimensions, composition, and level of purity. Additionally, the efficiency of the engineered nanocomposites for electrochemical hydrogen storage has been assessed through cyclic voltammetry and galvonastatic charge–discharge methods. The discharge capacity value of NiFe₂O₄/Fe₂O₃/g-C₃N₄ ternary nanocomposites at constant current (± 1 mA) in an alkaline solution (KOH 2.0 M) was obtained to be 900 mAh/ after 15 cycles, while this value of NiFe₂O₄ nanostructure and NiFe₂O₄/Fe₂O₃ nanocomposite was estimated about 480 and 725 mAh/g at the same condition, respectively. Based on the results, electrochemical hydrogen storage capacity of NiFe₂O₄/Fe₂O₃/g-C₃N₄ has been improved due to the several reasons including (i) formation of new sites through the charge and discharge reaction at the working electrode surface, (ii) high specific surface area of graphitic carbon nitride (g-C₃N₄) and (iii) synergistic effect between each component of final nanocomposite. NiFe₂O₄/Fe₂O₃/g-C₃N₄-based ternary nanocomposites display superior hydrogen sorption during the physisorption process, redox reaction and spillover mechanism which confirms the NiFe₂O₄/Fe₂O₃/g-C₃N₄ nanocomposites are favorable candidate to use for hydrogen storage application.