The segregation resistance of the Pt_2ML/Os/Pd₃Al sandwich catalyst for oxygen reduction reaction: a density functional theory study

Abstract

Pt/PdAl, which comprises a PdAl core protected by a Pt monolayer, may experience Al dealloying because of the strong affinity of Al toward O. To circumvent this issue, the Pt/Os/PdAl catalyst has been designed to suppress the migration of Al by inserting an Os monolayer at the interface between the PdAl core and two Pt monolayers. On the basis of segregation energies, Al leaching from the core to the 1st layer is determined to be endothermic even under O coverage, indicating an energetic preference for Al to reside in the core structure. The Pt/Os/PdAl catalyst benefits from the energetic disadvantage of the inward movement of Os and the presence of the 2 ML Pt layer. As an ORR electrocatalyst, the relatively weak adsorption ability of Pt/Os/PdAl suggests improved ORR activity. Finally, a representative OOH association mechanism with low reaction barriers of 0.46, 0.31, 0.38 and 0.41 eV for the OOH formation, OOH dissociation, OH formation and HO formation steps suggests that the catalyst can effectively activate the O-O bond and eliminate OH, which can act as a catalytic poison. These findings suggest the design of stable sandwich catalysts as potential candidates for ORR electrocatalysis.

Ultrafine Pt Nanoparticle-Decorated 3D Hybrid Architectures Built from Reduced Graphene Oxide and MXene Nanosheets for Methanol Oxidation

“…Therefore, the Pt4 nanocluster interacts more strongly with Ti 3 C 2 T x than that with the graphene support. Generally, the adsorption ability of transition metals toward molecules could be interpreted in terms of the d-band model, where an upshift of the d-band center (ε d ) to the Fermi energy level causes an upshift of the antibonding orbitals, potentially making them more difficult to fill, which renders a stronger binding interaction between the adsorbed molecules and reactive surfaces. − The strong interaction between Pt4 NP and Ti 3 C 2 T x may result in a downshift of d-band centers relative to the Fermi energy (ε F ) of the Pt NP, which will reduce the overlap between the d-band of the Pt NP and the sp-band of CO and cause the weaker adsorption of the CO molecule. The partial density of states (PDOSs) for Pt4 nanocluster on different substrates are shown in Figure C, where the d-band centers are −1.98 and −1.45 eV for Pt4 on Ti 3 C 2 T x and graphene, respectively, consistent with the XPS results.…”

Electrochemical Energy Conversion on Intermetallic Compounds: A Review

“… The durability is assigned to the strong interaction between Al–Ni and Al–Pt, while the mass-specific activity gain over Pt/C by a factor of 17.1 is assigned to compressive strain in the Pt shell as well as ligand effects. DFT calculations predicted even higher ORR for Pt-coated Pd 3 Al due to decreased oxygen binding energy and a decreased surface Pt leaching, while introducing an Os-interlayer between the Pt skin and the Pd 3 Al bulk hinders Al leaching from the bulk …”

“…DFT calculations predicted even higher ORR for Ptcoated Pd 3 Al due to decreased oxygen binding energy and a decreased surface Pt leaching, 142 while introducing an Osinterlayer between the Pt skin and the Pd 3 Al bulk hinders Al leaching from the bulk. 143 Pt 3 Sc (Cu 3 Au type of crystal structure) was investigated in a systematic study demonstrating its instability in air and ORR conditions, as scandium gets leached not only from the surface but also from the whole volume, leaving behind a Ptskeleton. 144 The initial activity was accounted to an electronic effect, which diminishes with time.…”

How to Boost the Activity of the Monolayer Pt Supported on TiC Catalysts for Oxygen Reduction Reaction: A Density Functional Theory Study

“…The double numerical atomic orbital augmented by a polarization function is chosen as the basis set [30]. Herein, the PBE/DNP combination in Dmol 3 code has been widely employed for the ORR electrocatalysis [7,8,34,35,36]. Furthermore, these parameters have been used for the TiC@Pt or TiN@Pt system [37].…”

“…The core-shell structure with a non-Pt core can significantly improve the Pt utilization, thereby reducing the Pt content and, thus, the cost [7,8]. It as previously revealed that when transition metal (TM) elements acted as the core, such as Pd [9,10], Ru [11], or Ir [12], the ORR activity of the corresponding TM@Pt core-shell was enhanced compared with the commercial Pt/C.…”