Active Site and Electronic Structure Elucidation of Pt Nanoparticles Supported on Phase-Pure Molybdenum Carbide Nanotubes

The performance of an atomically dispersed oxygen reduction catalyst prepared by γ-CD-MOF integration with FePc

Here, a series of Fe/N/C catalysts with different proportions and pyrolysis temperatures are prepared by co-pyrolysis of melamine with a γ-cyclodextrin metal-organic framework (γ-CD-MOF) containing iron(ii) phthalocyanine (FePc). Due to the restriction effect of the host and guest at the molecular level, γ-CD-MOF can effectively avoid the π-π stacking of FePc and restrain the agglomeration of Fe atoms during pyrolysis. The phases and structures of the catalysts are characterized, which proves that the obtained catalyst has a three-dimensional porous and internal cavity structure with abundant surface area (1055.317 m² g^-1) and Fe is atomically dispersed in nitrogen-doped carbon. The onset potential (0.988 V vs. RHE) and half-wave potential (0.846 V vs. RHE) of FePc@CD/M (1 : 20)-1000 are superior to those of a commercial 20% Pt/C catalyst. FePc@CD/M (1 : 20)-1000 also exhibits an approximately four-electron (3.84) transfer process, good stability and excellent methanol tolerance.

Effect of Platinum, Gold, and Potassium Additives on the Surface Chemistry of CdI2-Antitype Mo2C

Transition metal carbides are versatile materials for diverse industrial applications including catalysis, where their relatively low cost is very attractive. In this work, we present a rather extensive density functional theory study on the energetics of adsorption of a selection of atomic and molecular species on two Mo terminations of the CdI₂ antitype phase of Mo₂C. Moreover, the coadsorption of CO in the presence of preadsorbed metal atoms and its dissociative adsorption in the absence and presence of preadsorbed Pt and K were investigated. By using CO as a probe to understand the structural/electronic effects of the preadsorption of the metal atoms on the Mo₂C(001) surface, we showed that K further enhances CO adsorption/activation on the surface, in contrast to the precious metals considered. Moreover, it was observed that the presence of both Pt and K stabilizes the transition state for the C-O bond dissociation, lowering the activation barrier for the dissociation of the C-O bond by about 0.3 and 0.4 eV, respectively.