Electronic Structure Modulation of Nb2O5 by Ru Single Atoms Enabling Efficient Hydrogen Storage of Magnesium Hydrides.

Abstract

Magnesium hydride (MgH2) is a promising solid-state hydrogen storage material due to its high capacity and low cost, but its high dehydrogenation temperature and poor kinetic limits its applications. Although catalytic modification of MgH2 has been extensively studied, existing efforts focus on optimizing hydrogen transfer, with limited exploration of electron transfer and transport. This study investigated the enhancement of electron transfer and transport rates during MgH2 de/hydrogenation by introducing a single-atom catalyst composed of Ru single atoms on a Nb2O5 substrate. The Ru0.028@Nb2O5 single-atom catalyst reduced the peak dehydrogenation temperature of MgH2 from 429 to 214 °C, and the activation energies for de/hydrogenation were reduced by 53.7% and 83.9%, respectively. Furthermore, the 15wt%-Ru0.028@Nb2O5-MgH2 composite maintained 97.4% capacity after 100 cycles. Based on excellent performance and theoretical calculations, it was demonstrated that the electronic structure modulation of Nb2O5 by Ru single atoms enhanced the electron transfer and transport capacities, and the synergistic effects of single-atom Ru (dominant role), multivalent Nb, and oxygen vacancies resulted in remarkable catalytic activity. This study offers a new strategy for improving electron transfer and transport by modulating the electronic structure of catalysts, thereby increasing catalytic activity during the solid-state pyrolysis reaction of hydrogen storage materials.