Journal Article

Boosting Hydrogen Storage Performance of MgH2 by Oxygen Vacancy-Rich H-V2O5 Nanosheet as an Excited H-Pump

Li, Yinghui, Zou, Jianxin, Ren, Li, Ding, Wenjiang, Li, Zi, Lu, Chong, Lin, Xi

2024

Overview

HighlightsGraphene-like 2D V2O5 nanosheets rich in oxygen vacancies are designed as multi-functional catalysts to fabricate MgH2-H-V2O5 composites.Hydrogen release starts from 185 °C and capacity retention is as high as 99% after 100 cycles at 275 °C.The composites present rapid kinetics and impressive hydrogen absorption capability at near room temperature.The oxygen vacancies could directly enhance kinetics of MgH2 while indirectly exciting “hydrogen pump” effect of VH2/V.MgH2 is a promising high-capacity solid-state hydrogen storage material, while its application is greatly hindered by the high desorption temperature and sluggish kinetics. Herein, intertwined 2D oxygen vacancy-rich V2O5 nanosheets (H-V2O5) are specifically designed and used as catalysts to improve the hydrogen storage properties of MgH2. The as-prepared MgH2-H-V2O5 composites exhibit low desorption temperatures (Tonset = 185 °C) with a hydrogen capacity of 6.54 wt%, fast kinetics (Ea = 84.55 ± 1.37 kJ mol−1 H2 for desorption), and long cycling stability. Impressively, hydrogen absorption can be achieved at a temperature as low as 30 °C with a capacity of 2.38 wt% within 60 min. Moreover, the composites maintain a capacity retention rate of ~ 99% after 100 cycles at 275 °C. Experimental studies and theoretical calculations demonstrate that the in-situ formed VH2/V catalysts, unique 2D structure of H-V2O5 nanosheets, and abundant oxygen vacancies positively contribute to the improved hydrogen sorption properties. Notably, the existence of oxygen vacancies plays a double role, which could not only directly accelerate the hydrogen ab/de-sorption rate of MgH2, but also indirectly affect the activity of the catalytic phase VH2/V, thereby further boosting the hydrogen storage performance of MgH2. This work highlights an oxygen vacancy excited “hydrogen pump” effect of VH2/V on the hydrogen sorption of Mg/MgH2. The strategy developed here may pave a new way toward the development of oxygen vacancy-rich transition metal oxides catalyzed hydride systems.

• Publisher: Springer Nature B.V
• Subject: Absorption / Catalysts / Composite materials / Desorption / Graphene / Hydrogen / Hydrogen storage / Hydrogen storage materials / Kinetics / Nanosheets / Oxygen / Room temperature / Sorption / Temperature / Transition metal oxides / Vanadium pentoxide