Catalytic mechanism of TiO2 quantum dots on the de/re-hydrogenation characteristics of magnesium hydride. (29th October 2021)

• Record Type: Journal Article
• Authors: Pandey, Sunita Kumari; Bhatnagar, Ashish; Shukla, Vivek; Kesarwani, Rashmi; Deshpandey, Uday; Yadav, Thakur Prasad
• Is Part Of: International journal of hydrogen energy. Volume 46:Number 75(2021)
• Page Start: 37340
• Page End: 37350
• Publication Date: 2021-10-29
• Subjects: TiO2 quantum dots -- MgH2 -- Hydrogen storage -- De/re-hydrogenation stability; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2021.09.006
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: In the present study, the catalyst anatase titanium dioxide (TiO2 ) quantum dots (QDs) of size ∼ (2.50–4.00)nm was successfully synthesized by the hydrothermal method. The formation of TiO2 : QDs has been established by UV–Vis spectroscopy and confirmed by transmission electron microscopy. Here, we report the catalytic action of TiO2 :QDs on de/re-hydrogenation properties of magnesium hydride (MgH2 /Mg). By catalyzing MgH2 through this catalyst, the onset desorption temperature of MgH2 gets reduced significantly from ∼360 °C (for ball-milled MgH2 ) to ∼260 °C. Moreover, the Mg-TiO2 : QDs sample absorbed a significant amount of hydrogen up to ∼6.10 wt% in just 77sec at 280 °C. Improved rehydrogenation kinetics has been found even at lower temperatures by absorbing ∼5.30 wt% in 74 s at 225 °C and ∼5.0 wt% of hydrogen in 30 min at 100 °C. Based on structural, .microstructural, and XPS investigations, a feasible mechanism for improved hydrogen sorption and cyclic stability in MgH2 catalyzed with TiO2 :QDs has been explained and discussed. To our knowledge, no studies have been carried out on the sorption of hydrogen in MgH2 catalyzed by TiO2 :QDs. Highlights: TiO2 quantum dots were synthesized by the hydrothermal method. MgH2 catalyzed with the TiO2 :QDs shows good cyclic stability. Valency change of Ti, leads to improvement of dehydrogenation kinetics.