Photoemission study of electronic structures of disordered Ni-Pt and Cu-Pt alloys

Thermally Robust Porous Bimetallic (NixPt1–x) Alloy Mesocrystals within Carbon Framework: High-Performance Catalysts for Oxygen Reduction and Hydrogenation Reactions

“…This systematic shift of the characteristic Pt peak indicates that the Pt amount is well controlled at different ratios of the Ni x Pt 1– x alloy, in agreement with previously reported results. ,, Overall, the EDS and XPS results show that the elemental ratios of Ni and Pt in the alloy match the precursor ratio well. Such systematic regulation of the compositions of the Ni x Pt 1– x alloys via control of the precursor ratio indicates that the alloy reaction of the constituting precursors has successfully occurred, in agreement with the elemental mapping results obtained using STEM-EDS (Scheme C). ,,, As shown in Figure S1, the carbon framework of the Ni x Pt 1– x alloy was analyzed via XPS (Figure S1a) and Raman spectroscopy (Figure S1b). As shown in Figure S1a, the C1s spectra of the Ni x Pt 1– x alloy contain main peaks around 284 eV, corresponding to the CC bond of sp 2 -hybridized graphitic C and carbonate bonds, indicating the formation of a graphitic carbon shell on the surface of Ni x Pt 1– x alloy. , These XPS results suggest limited particle growth and hindered phase transformation of primary nanocrystalline Ni x Pt 1– x alloy due to carbon formed around them.…”

“…The Pt 4f (4f 7/2 ) peak of Ni 0.83 Pt 0.17 (71.5 eV) shifts to 71.2 eV with the addition of Pt atoms (Ni 0.5 Pt 0.5 ). This systematic shift of the characteristic Pt peak indicates that the Pt amount is well controlled at different ratios of the Ni x Pt 1– x alloy, in agreement with previously reported results. ,, Overall, the EDS and XPS results show that the elemental ratios of Ni and Pt in the alloy match the precursor ratio well. Such systematic regulation of the compositions of the Ni x Pt 1– x alloys via control of the precursor ratio indicates that the alloy reaction of the constituting precursors has successfully occurred, in agreement with the elemental mapping results obtained using STEM-EDS (Scheme C). ,,, As shown in Figure S1, the carbon framework of the Ni x Pt 1– x alloy was analyzed via XPS (Figure S1a) and Raman spectroscopy (Figure S1b).…”

Hydrogen Adsorption on Ordered and Disordered Pt-Ni Alloys

“…13% larger than that of Ni, which would impose a significant effective tensile strain on Ni atoms in a primarily Pt lattice [34,64]. All of these features are consistent with the valence-band photoemission spectra of Pt-Ni disordered alloys obtained by Nahm et al [65]. Overall, there are few distinct qualitative differences between Fig.…”

The quasiparticle band structures of ordered NixPt1-x

“…Recent developments [8] have shown that the non-local coherent potential approximation (NL-CPA) is effective in describing the electronic structure of disordered alloys; however, no re-investigation of the electronic band structure of the disordered Ni-Pt alloy or investigation of the ordered Ni-Pt alloys have been presented. Combined experimental and computational studies [9] have concluded that relativistic and self-consistent effects are required within KKR-CPA calculations in order to explain the weight of Pt states close to the Fermi level which are seen in experimental photoemission studies of the disordered Ni-Pt and Cu-Pt alloys. Later studies [10] concluded that electron correlation was one of the more probable causes of discrepancies between computational and experimental studies of Ni-Pt alloys.…”