Water dissociation on Pt nanoparticles adsorbed on carbon nanotubes: a DFT study

BELLETTI, GUSTAVO D.; QUAINO, PAOLA M.; NUÑEZ, JOSÉ L.; TIELENS, FREDERIK; TRANCA, IONUT

Bruselas

Conferencia; 19th International Conference on Density Functional Theory and its Applications; 2022

Vrije Universiteit Brussel

In this work, the deposition of Ptn nanoparticles (n = 1, 3, 7) on a (5, 5) carbon nanotube (CNT) support, as well as their role as catalysts in the water dissociacion reaction, were analyzed by means of density functional theory (DFT). Periodic DFT calculations were performed with the VASP code, which included long range (van der Waals) interactions considered within the DFT-D3 approach. For the water dissociation reaction, the nudged elastic band (NEB) method was used to find  minimum energy paths and the corresponding activation energy  barriers. The results of a methodical analysis of platinum nanostructures and insertion sites shows that the hybrid Ptn/CNT systems are  energetically stable (with interaction energies ranging from −1.0 eV to −3.6 eV) and exhibit charge redistribution ?especially on the deposited metal clusters? that affects their reactivity. The nature of the deposited  Pt particles sizes and geometries, along with charge accumulation due to  their interaction with the CNT, led to low activation energy barriers  for the water dissociation reaction, compared to those reported for  Pt(111) surfaces (0.78 eV). Figure 1 shows the initial (left), transition (middle) and final (right) states for a particular reaction path over a Pt3/CNT system, which showed a remarkably low energy barrier (0.30 eV). The DFT methods described above allows us to obtain an atomic-scale insight of the adsorption and dissociation processes, yielding  results that suggest a double benefit in the material performance as an  electrocatalyst: the decrease in the energy barrier for the water  dissociation, and the use of lower amounts of the precious metal on  modern catalysts.