MgH2 nanoparticles confined in reduced graphene oxide pillared with organosilica: a novel type of hydrogen storage material

TL;DR

This paper introduces a novel layered heterostructure scaffold of reduced graphene oxide and organosilica for hosting MgH2 nanoparticles, significantly enhancing hydrogen storage performance and kinetics at lower temperatures.

Contribution

It presents a new layered heterostructure scaffold that effectively confines MgH2 nanoparticles, improving hydrogen storage capacity and kinetics compared to bulk MgH2.

Findings

Hydrogen desorption starts at 50°C and peaks at 348°C.

Reversibility with 1.62 wt.% capacity over four cycles at 200°C.

MgH2 nanoparticles confined in the scaffold show superior storage properties.

Abstract

Hydrogen is a promising energy carrier that can push forward the energy transition because of its high energy density (142 MJ kg-1), variety of potential sources, low weight and low environmental impact, but its storage for automotive applications remains a formidable challenge. MgH2, with its high gravimetric and volumetric density, presents a compelling platform for hydrogen storage; however, its utilization is hindered by the sluggish kinetics of hydrogen uptake/release and high temperature operation. Herein we show that a novel layered heterostructure of reduced graphene oxide and organosilica with high specific surface area and narrow pore size distribution can serve as a scaffold to host MgH2 nanoparticles with a narrow diameter distribution around ~2.5 nm and superior hydrogen storage properties to bulk MgH2. Desorption studies showed that hydrogen release starts at 50 {\deg}C, with a maximum at 348 {\deg}C and kinetics dependent on particle size. Reversibility tests demonstrated that the dehydrogenation kinetics and re-hydrogenation capacity of the system remains stable at 1.62 wt.% over four cycles at 200 {\deg}C. Our results prove that MgH2 confinement in a nanoporous scaffold is an efficient way to constrain the size of the hydride particles, avoid aggregation and improve kinetics for hydrogen release and recharging.