Catalytic mechanism of TiO2 quantum dots on the de/re-hydrogenation characteristics of magnesium hydride

• Published in: International journal of hydrogen energy 2021-10, Vol.46 (75), p.37340-37350
• Main Authors: Pandey, Sunita Kumari, Bhatnagar, Ashish, Shukla, Vivek, Kesarwani, Rashmi, Deshpandey, Uday, Yadav, Thakur Prasad
• Format: Article
• Language: English
• Subjects: De/re-hydrogenation stability; Hydrogen storage; MgH2; TiO2 quantum dots
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2021.09.006

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. •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.