Evidence for the Formation of Nitrogen-Rich Platinum and Palladium Nitride Nanoparticles

Abstract

We report evidence for the formation of nitrogen-rich precious metal nanoparticles (Pt, Pd) prepared by reactive sputtering of the pure metal in a N2 plasma. The composition of the nanoparticles varies as a function of particle size and growth conditions. For the smallest particles the nitrogen content appears to be as high as 6.7 N atoms for each Pd atom or 5.9 N atoms for each Pt atom whereas bulk films have nominal compositions of Pt7.3N and Pd2.5N. The unusually large N content in the nanoparticles is balanced with H. The nanoparticles are metastable in air and moisture, slowly decomposing over several years. The catalytic properties of these N-rich nanoparticles were accessed by rotating disk electrode electrochemical studies, the liquid phase oxidation of benzyl alcohol, and gas phase CO oxidation, and support the experimental evidence for the materials composition.

High performance platinum single atom electrocatalyst for oxygen reduction reaction

“…1c ) shows five different bonding configurations of N atoms. Besides the well-known four types of N, pyridine-like (P-N, 398.3 eV, 42.9%), pyrrole-like (Py-N, 399.9 eV, 24.3%), graphitic (G-N, 400.1 eV, 15.7%) and oxidized (O-N, 403.3 eV, 7.3%) nitrogen, interestingly, similar to the formation of Fe-N bonding observed on Fe-N x /C catalysts 19 20 , Pt-N bonding (399.2 eV, 8.1%) was also observed 21 , indicating a strong interaction between single Pt atoms and the neighbouring doped-N due to the anchoring effect of doped-N to individual Pt atoms observed from above HAADF images. As for the Pt 4f XPS data for Pt 1 -N/BP, as shown in Fig.…”

Structural selectivity of supported Pd nanoparticles for catalytic NH3 oxidation resolved using combined operando spectroscopy

“…22 However, the absence of carbon in this system leads us to infer the formation of another type of interstitial structure, palladium nitride. 32 Upon repeating this procedure with a gas feed of 0.5% NH3/He, the same result is obtained ( Supplementary Figure 6), showing that the same structural phase is also formed without the presence of O2. Further evidence of the Pd nitride species was inferred from XPS spectra of the sample after treating with NH3 gas.…”

“…The N1s species located at 400 eV is consistent with NH3 molecular species, whereas the species located at 395 eV is consistent with the formation of a reduced nitrogen as in metal nitrides. 32 Operando Pd K-edge XAFS. The change in electronic structure of the Pd species upon exposure to the reactant NH3/O2/He gas feed is confirmed again by comparison of the Pd K-edge XANES recorded before and after gas switching from inert to NH3/O2/He, as seen in Figure 3a.…”

Tailored Electron Transfer Pathways in Aucore/Ptshell–Graphene Nanocatalysts for Fuel Cells

“…Therefore, the presence of N–graphene bonds is evidenced in the N 1s XPS spectrum of G‐Cys‐Au@Pt (Figure E). Three peaks are centered at 398.2, 400.0, and 402.1 eV, corresponding to metal–nitrogen (MeN) bond, amide, and oxidized N (N ox ), respectively . The MeN peak originates from MES at the Au NP surface, dominating the N spectrum due to significantly larger domains of MES capping than Cys anchors.…”

“…The interconnected structure of G-Cys-Au@Pt and the presence of Cys covalent bonding was studied by XPS, Figure 2D-F. XPS spectra of S 2p, deconvoluted into spin-orbit doublets at 162.2 and 163.1 eV are assigned to SAu interactions. Three peaks are centered at 398.2, 400.0, and 402.1 eV, corresponding to metal-nitrogen (MeN) bond, [29] amide, and oxidized N (N ox ), respectively. Peaks at 163.8 and 165.0 eV are from free thiol (SH) [23,24] and peaks at 166.9 and 168.2 eV from SO 3 −[25] in the MES capping around the NP surface.…”