Hydrogen and oxygen recombination reaction on Pt–Ni and Pt–Co based alloys using density functional theory

• Published in: Surface science 2023-10, Vol.736, p.122354, Article 122354
• Main Authors: Botha, LM, Ouma, CNM, Obodo, KO, Bessarabov, D.
• Format: Article
• Language: English
• Subjects: Bimetallic Pt–Ni; Density functional theory; H2/O2 recombination; Hydrogen crossover; Passive autocatalytic recombiners; Pt–Co catalysts
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/j.susc.2023.122354

•The understanding of Pt3Co, Pt3Ni and PtNi3 alloys for the catalytic H2/O2 recombination reaction is limited.•In this manuscript using spin-polarized density functional simulations (DFT), the electronic properties, along with the catalytic activity, of Pt3Ni, Pt3Co and PtNi3 (111) surfaces were investigated.•This was done by determining the surface stability, interaction strength between the surface and reaction intermediates, and the catalytic activity.•The (111) miller index resulted in stable surfaces of the Pt3Co, PtNi3 and Pt3Ni surfaces, while PtNi and PtCo were unstable.•Strong surface adsorption occurred on the Pt3Ni (111) surface while weak surface adsorption occurred on the Pt3Co (111) surface.•The surfaces with weaker adsorption properties (Pt3Co and Pt3Ni) performed better in the slow OH formation step than either the PtNi3 or Pt (111) surfaces.•The performance of the weak surface adsorption surfaces (Pt3Co and Pt3Ni) was lower in the H2O formation step than either the PtNi3 or Pt (111) surfaces.•We concluded that the Pt3Co (111) surface acted as a better catalyst for the H2/O2 recombination reaction compared to Pt3Ni (111) surface, both of which showed better performance than the Pt (111) surface. Density functional theory (DFT) calculations were used to investigate the surface performance of Pt, Ni, Co, and PtxTM1-x (0 ≤ x ≤ 1) alloys, as well as reaction intermediates (O, H, OH, OH + H, H2O) on these surfaces for H2/O2 recombination. The activity of the PtxTM1-x alloys towards H2/O2 recombination reaction was probed using adsorption energies and reaction energies. The Pt3Co, Pt3Ni and PtNi3 alloys were found to be stable along the (111) miller index, with strong surface adsorption occurring on the PtNi3 (111) surface and weaker adsorption on the Pt3Co (111) surface. Enhanced reactivity was observed on the Pt3Ni and Pt3Co (111) surfaces for the (O*  +  H*  →  OH*) reaction step, while the Pt (111) surface was most suited for the (OH*  +  H*  →  H2O) reaction step. The OH* formation reaction step was inhibited on the PtNi3 (111) surface due to the strong surface absorption of the reaction intermediates. Overall, these results suggest that the Pt3Co (111) surface is a promising alternative catalyst for H2/O2 recombination compared to pristine Pt due to its performance in the O + H adsorption and OH* formation steps. [Display omitted]