Enhancing tunneling, microstructural morphology, and electrochemical performance of carbon fiber substituted ternary alloys (Mg-Ni-Ti) synthesized via mechanical alloying for hydrogen storage applications: Activation energy reduction and hydrophobic benefits

This study focuses on the preparation of Mg-Ni-Ti ternary alloys substituted with varying weight ratios of carbon fiber, synthesized using mechanical alloying for hydrogen storage applications. X-ray diffraction (XRD) analysis confirms the presence of carbon in the ternary alloy at 2θ = 71° along with the ternary alloy characteristic peaks. The substitution of carbon fiber increases the dislocation density from 5.3x10⁻³ nm⁻² to 7.845x10⁻³ nm⁻² and significantly enhances the strain within the samples. Selected area diffraction (SAED) confirms the formation of alloys as well presence of carbon. High-resolution Transmission Electron Microscopy shows carbon encapsulated in metal alloy particles, which helps as a barrier to resist the corrosion of metal alloy. Carbon fiber substitution lowers the activation energy of Mg-Ti-Ni from 79.96 kJ/mol to 65.54 kJ/mol, as estimated by Kissinger's analysis. Cyclic Voltammetry (CV) analysis for the alloy substituted with carbon fiber has unveiled a more substantial reduction peak than the oxidation peak, attributed to the hydrophobic nature of carbon fiber. The oxidation property of carbon fiber also reduces the corrosion rate from 0.146 mgpy to 0.083 mgpy. Hydrogen absorption/desorption studies for carbon fiber substituted ternary alloy have indicated that the ternary alloy with 5 wt% carbon fiber substitution has achieved a maximum higher discharge capacity of 1020 mAhg⁻¹.