Highly dispersed nickel catalysts via a facile pyrolysis generated protective carbon layer

Abstract

In situ generated protective carbon layers from metal precursor pyrolysis produce a highly dispersed Ni catalyst by restricting the metal mobility and agglomeration.

Controlled colloidal metal nanoparticles and nanoclusters: recent applications as cocatalysts for improving photocatalytic water-splitting activity

“…5A). 175 Also, it is not possible to apply methods such as size separation and size convergence to these loaded metal NPs/NCs, unlike metal NPs/NCs dispersed in a solution. Therefore, it is difficult to load cocatalysts with a uniform size on photocatalysts using these conventional methods.…”

The Relationship between Reaction Temperature and Carbon Deposition on Nickel Catalysts Based on Al2O3, ZrO2 or SiO2 Supports during the Biogas Dry Reforming Reaction

“…Surprisingly, for both Ni/Si and Ni/Zr, the mean Ni particle size of the spent catalysts is smaller than the reduced ones. A possible explanation is the melting and confining of Ni particles inside the carbon fibers, which then acts as a protective coating preventing them from sintering [57].…”

“…As mentioned previously, the mean particle size of the reduced catalysts was calculated at 5.3 nm (± 1.3 nm), 48.2 nm (± 16.6 nm) and 56.2 nm (± 21.1 nm) for the Ni/Al, Ni/Zr and Ni/Si, respectively. The relatively large particle size of the latter catalysts can be attributed to the high Ni surface loading observed for these samples (XPS measurements) and the ease of Ni sintering during the calcination and reduction steps [57]. for the Ni/Zr catalyst after the reaction at 800 °C (d-e) Particle size distribution histograms after the reaction at 600 °C and 800 °C.…”

“…This conclusion (melting) is also supported by a change in the shape of the Ni particles, from mainly pseudo-spherical to a mixture of pseudo-spherical and rod shaped ( Figure 5). Das et al [57] has suggested that the carbon coating the nanoparticles has the ability to then prevent further sintering from taking place. Moreover, the carbon formed on to the Ni/Zr surface is less graphitic and more defective in comparison to the Ni/Al, possibly due to the increased bacisity of this material.…”

Hidróxidos duplos lamelares como precursores de nanopartículas metálicas e nanoestruturas de carbono

“…Assim sendo, para materiais obtidos em temperaturas menores que 1000 °C, a camada grafítica que envolve as Ni-NPs atua no controle do seu tamanho, como uma barreira difusional adicional para a sua coalescência. Resultado semelhante já foi reportado para partículas de níquel, 167 ouro 168 e prata 169 . Por outro lado, as nanopartículas metálicas favorecem a grafitização da matriz carbonácea, além da obtenção de estruturas com diferentes morfologias (fitas e esferas), como as nanoonions de carbono evidenciadas na Figura 41c.…”