Abstract
Herein, we report on a novel method for deposition of Mg nanoparticles at the surface of carbon materials. Through the suspension of carbon nanotubes (CNTs) in an electrolyte containing di-n-butylmagnesium as a precursor, Mg nanoparticles were effectively deposited at the surface of the CNTs as soon as these touched the working electrode. Through this process CNTs supported Mg particles as small as 1 nm were synthesised and the distribution of the nanoparticles was found to be influenced by the concentration of the CNTs in the electrolyte. Hydrogenation of these nanoparticles at 100C was found to lead to low temperature hydrogen release starting at 150C, owing to shorter diffusion paths and higher hydrogen mobility in small Mg particles. However, these hydrogen properties drastically degraded as soon as the hydrogenation temperature exceeded 200C and this may be related to the low melting temperature of ultrasmall Mg particles.
Highlights
Magnesium (Mg) is a promising candidate for hydrogen storage with a high gravimetric capacity of 7.6 mass% H2 and a volumetric density of ~110 kg m−3 H2 (Sun et al, 2017)
Magnesium–carbon nanotubes (CNTs) composites were successfully synthesized through electrochemical deposition with the CNTs suspended in the electrolyte, and this demonstrated for the first time an alternative method to effectively generate ultra-small Mg particles at the surface of carbon materials
The hydrogen release at low temperatures was assigned to the ultra-small Mg particles on CNTs’ surface, while the high temperature hydrogen desorption most likely corresponded to larger Mg particles contained within the composite material
Summary
Magnesium (Mg) is a promising candidate for hydrogen storage with a high gravimetric capacity of 7.6 mass% H2 and a volumetric density of ~110 kg m−3 H2 (Sun et al, 2017). Carbon materials have been widely used to nanoconfine Mg and achieve better hydrogen storage properties especially in terms of kinetics (Yao et al, 2006; Lillo-Ródenas et al, 2008; de Jongh and Adelhelm, 2010; Skripnyuk et al, 2010; Adelhelm and de Jongh, 2011). This includes graphene, carbon nanotubes (CNTs), and carbon aerogels (Liu et al, 2013; Cai et al, 2015; Xia et al, 2015; Shinde et al, 2017).
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