Hydrogen Splitting using Single Metal Atom Doped Zinc Oxide Nanocage as a Catalyst: A DFT Study

Abstract

Hydrogen dissociation reaction is a key step in sustainable, non-toxic and renewable energy production and single atom catalysts have shown promising catalytic activity in facilitating this reaction. The world is currently facing major challenges related to the environment, including climate change and the depletion of non-renewable energy sources. As a potential solution to these challenges, the use of clean and renewable energy sources, such as hydrogen, has gained increasing attention. Herein we employed DFT calculation on single atom catalyst-based study to investigate the adsorption and dissociation of H2 molecule over TM@ Zn12O12 catalysts. The analysis of the interaction energy reveals the stability of all transition metal doped complexes (Sc-Mn), with the highest interaction energy (-4.27 eV) observed in the Cr@Zn12O12 complex. Furthermore, electronic properties (FMOs, NBO analysis) confirm the electropositive nature of transition metal atoms. QTAIM and IRI analysis are employed to interpret shared or partially covalent interactions in TM@ Zn12O12 complexes. The mechanism of hydrogen dissociation reaction is studied for all the complexes (Sc-Mn), and it is found that Sc@Zn12O12 is the most efficient catalytic agent for the hydrogen dissociation reaction, with the lowest activation barrier (0.09 eV). EDD isosurface and NBO analysis confirm the charge transfer from metal to antibonding orbital of hydrogen which facilitates the hydrogen splitting. The pivotal insights gained from this study enhance our understanding about the stability, electronic properties, and hydrogen dissociation reaction of various transition metal doped Zn12O12complexes.