Fabrication and characterisation of Ni/Ti/Ni/Ti multilayer thin film systems for hydrogen storage applications

Abstract

This study explores the fabrication and characterisation of Ni/Ti/Ni/Ti multilayers for hydrogen storage. The thin films were fabricated using the e-beam under high vacuum pressure to allow for precise control over the film thickness. Rutherford backscattering spectrometry was used to study the elemental composition of the film stacks, and elastic recoil detection analysis was used for hydrogen profiling. X-ray diffraction (XRD) and atomic force microscopy were used for structural and morphological analysis of the samples. The results revealed that the nickel layer was pure and contained no impurities. The hydrogen absorption was found to be temperature-sensitive, with maximum absorption at 200 (Formula presented.) C with a total hydrogen content of 46.42 at.%. XRD confirmed the formation of titanium hydride (TiH (Formula presented.)), at higher temperatures and the titanium peaks becoming more prominent at 500 (Formula presented.) C. Surface roughness analysis revealed a correlation between the roughness of the samples and hydrogen absorption; the highest roughness was recorded at 200 (Formula presented.) C. The nickel layer acted as a catalyst, enhancing hydrogen dissociation and minimising the negative impacts of oxides. These findings demonstrate the potential for the use of Ni/Ti/Ni/Ti for efficient hydrogen storage, with the optimal temperature being 200 (Formula presented.) C.