Direct Observation of Ni–Mo Bimetallic Catalyst Formation via Thermal Reduction of Nickel Molybdate Nanorods

Abstract

We used in situ environmental transmission electron microscopy to image the formation of a Ni−Mo composite nanocatalyst via thermal reduction of NiMoO 4 nanorods. Two clear structural changes were observed as the temperature was increased from 25 to 500 °C in the presence of H 2 (g): the first involved nucleation of nanoscale Ni-rich particles and the second involved general collapse of the remaining oxide phase along with substantial coarsening of the alloy particles. The activity of the catalyst toward alkaline hydrogen evolution was found to reach a maximum in a narrow range of reduction temperatures from 375 to 425 °C. This resulted in the formation of a mixed-phase product comprising sub-10 nm Ni 0.9 Mo 0.1 particles embedded in a porous Mo-rich oxide matrix. Thus, the most active Ni−Mo catalyst apparently requires intimate contact between the alloy component and the oxide phase, lending support to a catalytic mechanism involving metallic and oxidized surface sites.

Rapid Synthesis of Various Electrocatalysts on Ni Foam Using a Universal and Facile Induction Heating Method for Efficient Water Splitting

“…In addition, X‐ray photoelectron spectroscopic (XPS) measurements were carried out to study the surface elemental composition as well as the oxidation states of NiMoO 4 /NF‐IH and NiFe LDH/NF‐IH, [ 20 ] as shown in Figure S5b,c in the Supporting Information. In Figure 2i, the Ni 2p 1/2 and Ni 2p 3/2 peaks of NiMoO 4 /NF‐IH are situated in 874.4 and 856.5 eV, respectively, accompanied with two satellite peaks.…”

Hydrodesulfurization of 4,6-Dimethyldibenzothiophene and the Diesel Oil Fraction on NiMo Catalysts Supported over Proton-Exchanged AlMCM-41 and TiMCM-41 Extrudates

“…857.7 eV can be also associated with the presence of Ni2O3 over the NiMo/HAlMCM-41 surface [52]. In addition, based on references [53][54][55], the signal at a higher BE (ca. 857 eV) can be assigned to NiMoO4 or NiAl2O4 species.…”

The role of Mo species in Ni–Mo catalysts for dry reforming of methane

“…16,65 Owing to the reaction of DRM taking place at high temperature, NiMoO x or MoO x species may be formed in the Ni-Mo catalysts. 11,23,49 And the presence of nickel could facilitate the reduction of MoO x , 66,67 which may be the reason for the removal of surface carbon due to the easier oxidation of carbon species.…”