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Ni–Fe bimetallic electrocatalysts are expected to replace existing precious metal catalysts for water splitting and achieve industrial applications due to their high intrinsic activity and low cost. However, the mechanism by which Ni and Fe species synergistically enhance catalytic activity remains obscure, which still needs further in‐depth study. In this study, a highly active bi‐functional electrocatalyst of Ni2P/FeP heterostructures is constructed on Fe foam (Ni2P/FeP‐FF), clearly illustrating the effect of Ni on Fe species for oxygen evolution reaction (OER) and revealing the true catalytic active phase for hydrogen evolution reaction (HER). The Ni2P/FeP‐FF only needs overpotentials of 217 and 42 mV to reach 10 mA cm−2 for OER and HER, respectively, exhibiting superior bi‐functional activity for overall water splitting. The Ni can elevate the strength of FeO on Ni2P/FeP‐FF surface and promote the formation of high‐valence FeOOH phase during OER, thus enhancing OER performance. Based on first‐principles calculations and Raman characterizations, the Ni2P/Ni(OH)2 heterojunction evolved from Ni2P/FeP is identified as the real high active phase for HER. This study not only builds a near‐commercial bifunctional electrocatalyst for overall water splitting, but also provides a deep insight for synergistic catalytic mechanism of Ni and Fe species. [ABSTRACT FROM AUTHOR]

In this study, a series of Ni10MoxAl composite metal oxide (Ni10MoxAl, NiO = 10 wt.%, x = 2.5, 5, 10, 15, 20 wt.%) catalysts with different Mo content were prepared by a solvothermal method using a water—ethanol system. By employing various characterization technologies, it was confirmed that the suitable amount of the Mo element can not only promote the dispersion of the Ni species but also inhibit the formation of the inactive NiAl2O4 phase. Consequently, the hydrogenation activity of the Ni10MoxAl catalysts was affected by the particle size of the active components and the amount of the NiAl2O4 phase. As a result, the Ni10Mo10Al catalyst showed the best catalytic performance on methyl acrylate hydrogenation, and the yield of methyl propionate can be increased from 53.7% to 89.5% at 100 °C and 1 MP H2, compared with the Ni10Mo10/γ–Al2O3 catalyst prepared by a traditional impregnation method. The stability of the Ni10Mo10Al catalyst was also investigated, and the catalyst can run stably for 23 h. The novel strategy adopted in this article provides a new direction for the preparation of high activity Ni–Mo catalysts. [ABSTRACT FROM AUTHOR]

In this study, a series of Ni10MoxAl composite metal oxide (Ni10MoxAl, NiO = 10 wt.%, x = 2.5, 5, 10, 15, 20 wt.%) catalysts with different Mo content were prepared by a solvothermal method using a water—ethanol system. By employing various characterization technologies, it was confirmed that the suitable amount of the Mo element can not only promote the dispersion of the Ni species but also inhibit the formation of the inactive NiAl2O4 phase. Consequently, the hydrogenation activity of the Ni10MoxAl catalysts was affected by the particle size of the active components and the amount of the NiAl2O4 phase. As a result, the Ni10Mo10Al catalyst showed the best catalytic performance on methyl acrylate hydrogenation, and the yield of methyl propionate can be increased from 53.7% to 89.5% at 100 °C and 1 MP H2, compared with the Ni10Mo10/γ–Al2O3 catalyst prepared by a traditional impregnation method. The stability of the Ni10Mo10Al catalyst was also investigated, and the catalyst can run stably for 23 h. The novel strategy adopted in this article provides a new direction for the preparation of high activity Ni–Mo catalysts.

Abstract: The deoxygenation of rapeseed oil has been studied over sulfided NiMo-alumina catalysts (NiMoS-alumina). The main focus has been on the preparation of catalyst precursors (oxide form of sulfided NiMo-alumina catalysts – NiMoO-alumina) with a different distribution of Ni species in order to contribute to the understanding of the effect of catalyst preparation on the activity/selectivity of NiMoS-alumina catalysts in the deoxygenation of rapeseed oil. To analyze the state of Ni species the NiMoO-alumina catalysts have been characterized by UV–vis diffuse reflectance spectrometry (DRS), X-ray diffraction (XRD) and XPS. It has been found out that the NiMoO-alumina catalysts with higher population of octahedral nickel species resulted in more active NiMoS-alumina catalysts than those containing higher population of tetrahedral nickel species. [Copyright &y& Elsevier]

Two mesoporous material Ni/ γ-Al2O3 catalysts were prepared and characterized by ICP-AES, XRD, and TPR. The differences in reaction activity between Ni-in-Al2O3 and Ni-on-Al2O3 were investigated for hydrotreating of crude 2-ethylhexanol. The results show that the Ni species (Ni-on-Al2O3) exhibit excellent hydrogenation activities at a wide range of H2 pressure and space velocity, while the Ni species (Ni-in-Al2O3) exhibit similar activities with those of Ni-on-Al2O3 only at higher H2 pressure and lower space velocity. Due to the presence of extensively exposed Ni species on the Ni-on-Al2O3 catalyst, its hydrogenation performance was increased significantly because of the low interphase mass transfer resistance. [ABSTRACT FROM AUTHOR]

Abstract: A series of supported Ni/γ-Al2O3 samples were prepared and then used to identify the surface Ni species. The samples were characterized by ICP-AES, XRD, TPR, and XPS. The results indicated that two types of Ni species occurred on the samples with Ni loading<9.1wt%, while four types of Ni species occurred on the samples with Ni loading>9.1wt%. The reduction temperatures around 350, 500–520, 620–650, and 750–800°C corresponding to Ni species were related to amorphous NiO, crystal NiO, NiAl2O4, and NiAl x O y (x >2), respectively. A correlation was made between the catalytic activities and the surface Ni species. For the catalysts that were difficult to reduce (Ni loading<9.1wt%), the activities were very poor at low reduction temperatures; for the easily reducible catalysts (Ni loading>9.1wt%), the activities were excellent in a wider reduction temperature range from 400 to 800°C. [Copyright &y& Elsevier]