The one-pot synthesis of CuNi nanoparticles with a Ni-rich surface for the electrocatalytic methanol oxidation reaction

Abstract

Polyhedral Cu–Ni alloy nanoparticles with a Ni-rich surface were synthesized, and they exhibit very high activity during the methanol oxidation reaction.

Size‐Tunable Ni–Cu Core–Shell Nanoparticles—Structure, Composition, and Catalytic Activity for the Reverse Water–Gas Shift Reaction

“…The XRD pattern of the NP dispersion (black line in Figure 1d) exhibits reflections of crystalline Ni and Cu, indicating that the NPs contain crystalline domains. This finding of non-oxidized Ni and Cu in the XRD pattern is in accordance with Liu et al and An et al [34,36] STEM energy dispersive X-ray spectroscopy (EDX) measurements of these particles indicate the formation of a core-shell structure with Cu in the center surrounded by an Ni layer as evident from the line scan of representative particles (Figure 1e) and in the element mapping (Figure 1f, more detailed in Figure S2b, a less pronounced extend. However, the shoulder at the absorption edge is characteristic to pure Ni.…”

“…The XRD pattern of the NP dispersion (black line in Figure 1d) exhibits reflections of crystalline Ni and Cu, indicating that the NPs contain crystalline domains. This finding of non‐oxidized Ni and Cu in the XRD pattern is in accordance with Liu et al and An et al [ 34,36 ]…”

“…Similar characteristics were found by An et al, who found no signs of oxidation in the XRD pattern, while the XPS measurements indicated the existence of Ni, Cu, O, and C. [ 34 ] The characterization of Ni and NiCu NPs with XRD to ensure the purity [ 36,43 ] seems therefore not to be overall sufficient, but it gains by the combination of different methods, which are not relying on the crystallinity. [ 34,44 ]…”

“…The XRD data suggested non-oxidized NiCu NPs, while additional investigation with XAS, ASAXS, and XPS revealed the formation of an NiO shell in addition to metallic Ni and Cu. Similar characteristics were found by An et al, who found no signs of oxidation in the XRD pattern, while the XPS measurements indicated the existence of Ni, Cu, O, and C. [34] The characterization of Ni and NiCu NPs with XRD to ensure the purity [36,43] seems therefore not to be overall sufficient, but it gains by the combination of different methods, which are not relying on the crystallinity. [34,44] S8, Supporting Information.…”

Interstitial and substitutional light elements in transition metals for heterogeneous catalysis

“…For example, Cu can be alloyed into Ni, leading to the formation of a substitutional alloy. 16 The presence of Cu in the substitutional alloy system is anticipated to fill the d-band vacancies of Ni and suppress the formation of γ-NiOOH, which is a low-activity byproduct formed during electrocatalytic methanol oxidation. In the case of substitutional alloy formation in metal oxides, a small fraction of the metal cations of a host oxide can be substituted by foreign cations, 17 and/or the anions replaced by foreign anions such as halides.…”