EUBCE 2026 - Nomcebo MOTSA - DFT Study of Hydrogen Production from Catalytic Decomposition of Ammonia over Ru3 and Ru4 Clusters Catalysts

DFT Study of Hydrogen Production from Catalytic Decomposition of Ammonia over Ru3 and Ru4 Clusters Catalysts

Short Introductive summary

The decomposition of ammonia (NH3) represents a promising route for carbon-free hydrogen production. This study employs density functional theory (DFT) to investigate the decomposition mechanism of NH3 over 3-atom and 4-atom ruthenium clusters (Ru3 and Ru4) supported on a CeO2 surface. Structural optimizations, adsorption energy calculations, transition state searches, and electronic analyses such as density of states and Mulliken population analysis were conducted to assess catalytic performance. The adsorption studies revealed that intermediates bind more strongly on Ru4, with adsorption energies of -5.29 eV for NH2 and -3.93 eV for N2, compared to only -0.19 eV and -0.67 eV, respectively, on Ru3. Transition state calculations showed that Ru4 consistently exhibits lower activation barriers for NH3 dehydrogenation steps, such as 1.91 eV for NH2 NH + H versus 2.03 eV on Ru3, suggesting a more favourable decomposition pathway. The DOS analysis showed that the d-orbitals of the Ru atoms changed noticeably when molecules adsorbed onto the surface, suggesting that these orbitals play an active role in breaking chemical bonds during the reaction.

R. Chiwanga, University of Pretoria, SOUTH AFRICA
N. Motsa, University of Pretoria, SOUTH AFRICA
D. Oduma, University of Pretoria, SOUTH AFRICA
C.N.M. Ouma, African Institute for Mathematical Sciences, Kigali, RWANDA
E. Oko, Newcastle University, UNITED KINGDOM
M. Daramola, University of Pretoria, SOUTH AFRICA