Enhanced catalysis of Pd single atoms on Sc2O3 nanoparticles for hydrogen storage of MgH2

The controlled preparation of novel catalysts in solid-state hydrogen storage materials has attracted significant scholarly attention. In this study, a catalyst consisting of Pd single atoms supported on Sc2O3 nanoparticles (PdSA@Sc2O3) was synthesized by a simple method. The peak dehydrogenation temperature of MgH2 with the addition of 10 wt% PdSA@Sc2O3 is 310.1 °C, which is 62.5 °C lower than that of pure MgH2, showing a positive catalytic effect. Specifically, the MgH2-10 wt%PdSA@Sc2O3 with a low Pd content of 0.5 wt% can release 5.18 wt% of hydrogen at 300 °C in 15 min, with an initial release rate of 0.43 wt%/min. It can absorb 5.98 wt% of hydrogen at 250 °C in 3 min, and still uptake 5.17 wt% of hydrogen at 150 °C in 1 h. This indicates its ability to absorb hydrogen rapidly at high temperatures and continuously at low temperatures. For the catalytic mechanism, theoretical calculations indicate a significant electronic interaction between Pd and Sc2O3. The Pd single atoms loaded on Sc2O3 have nanoparticles higher hydrogen adsorption energy, which greatly improves the catalytic activity of Pd. Sc0 generated in-situ during dehydrogenation can destabilize the Mg-H bond and promote hydrogen dissociation. The Mg-Pd alloy produced during the hydrogen absorption and desorption process has an efficient hydrogen pumping effect, which contributes greatly to the kinetic properties of MgH2. The synergistic catalytic mechanism of Pd single atoms and Sc2O3 on de/hydriding of Mg/MgH2 was systematically investigated, which provides ideas for the commercial production of new controllable and prepared nanocatalysts.