ИСТИНА

Mono- and bilayer metallic slabs and clusters of precious metals (Au, Pd, Pt) were earlier studied at TiO2, carbides, nitrides, where their formation was more reliably evidenced. A fraction of monolayer clusters can be formed at small metal coverage where 2D slab can be instructive model to clarify the origin of catalytic activity. An accent at the “heterogeneity” of Pd atoms monolayer induced by interaction with a semi-ionic support was not discussed in details therein. Such analysis was undertaken herein for catalytic dissociation of methane, ammonia, and water. The geometry of Pd monolayer was optimized over the (100) and (110) planes of γ-Al2O3 and monoclinic ZrO2(001) at fixed unit cell parameters defined by the oxides. Simulation of deposition of flat Pd(100) monolayer cut from a bulk led to a formation of new distorted Pd monolayers whose favored form depends on the support. The subsequent chemisorption or dissociation of CH4 or H2O at these Pd monolayers can modify them resulting in new hybrid Pd structures containing alternate elements of the (100) and (111) planes. The stability of various hybrid Pd layers is compared to those of low index Pd planes and clusters. The catalytic capabilities of these monolayer structures have been demonstrated for CH4, H2O [1], NH3, and O2 dissociation at hybrid Pd(100)/(111) layer relative to those at pure (bulk) Pd(100) or Pd(111) surfaces. Moreover, moderate exothermic heats of these reactions were calculated instead of endothermic heats at the Pd(100) or Pd(111) surfaces. The relevance of the model of heterogeneous Pd monolayer for explaining the maximum of reaction rate experimentally observed at different Pd coverage is discussed. A transferability of the geometry and the extent of charge inhomogeneity of the hybrid monolayer were also tested at the same supports for other metals (Pt, Rh, and Ag) [1]. 1. A. A. Rybakov, et al. Dalt. Trans. 2021, 50, 8863.