Enhanced Activity of Supported Ni Catalysts Promoted by Pt for Rapid Reduction of Aromatic Nitro Compounds

Abstract

To improve the activities of non-noble metal catalysts is highly desirable and valuable to the reduced use of noble metal resources. In this work, the supported nickel (Ni) and nickel-platinum (NiPt) nanocatalysts were derived from a layered double hydroxide/carbon composite precursor. The catalysts were characterized and the role of Pt was analysed using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDS) mapping, and X-ray photoelectron spectroscopy (XPS) techniques. The Ni2+ was reduced to metallic Ni0 via a self-reduction way utilizing the carbon as a reducing agent. The average sizes of the Ni particles in the NiPt catalysts were smaller than that in the supported Ni catalyst. The electronic structure of Ni was affected by the incorporation of Pt. The optimal NiPt catalysts exhibited remarkably improved activity toward the reduction of nitrophenol, which has an apparent rate constant (Ka) of 18.82 × 10−3 s−1, 6.2 times larger than that of Ni catalyst and also larger than most of the reported values of noble-metal and bimetallic catalysts. The enhanced activity could be ascribed to the modification to the electronic structure of Ni by Pt and the effect of exposed crystal planes.

Catalytic Hydrogenation of Nitrophenols by Cubic and Hexagonal Phase Unsupported Ni Nanocrystals

“…During the reduction of NP, the positively charged nitrogen in nitro group can be easily attacked by the negatively charged active H atoms in metal‐H bonds, leading to the reduction of nitro group to nitroso group. The nitroso group can be further attacked by the negatively charged active H atoms to form hydroxylamine, and finally to obtain objective amino product . Combined previous reports with our experiment results, we conjecture that the active H atoms attached on fcc and hcp Ni NCs catalyst surface to form Ni−H bonds is the speed‐limiting steps for hydrogenation of 4(3, 2)‐NP to 4(3, 2)‐AP with NaBH 4 , and the plausible catalytic reaction mechanism or pathway are suggested.…”

“…According to previous reports,, the reaction of NaBH 4 with H 2 O can generate H 2 and NaBO 2 . In the presence of metal catalysts, the H−H bond in H 2 molecules can be cleaved to produce active H atoms, which will attach to the metal catalyst surface and form the desired metal‐H bonds ,,. In metal‐H structure, the active H atom bears a negative charge.…”

Comprehensive study of a versatile polyol synthesis approach for cathode materials for Li-ion batteries

“…Nanoparticles with only Ni or Co were not observed in other HAADF-STEM images as well (Figure S9). The closely magnified bright-field image and the corresponding FFT verified that Ni-Co alloy nanoparticles are well-crystalline with the observed d spacing of 0.20 nm and 0.17 nm between adjacent fringes, corresponding to the (111) and (200) crystal planes of face-centered cubic (fcc) structured Ni-Co alloy [51][52][53][54][55][56]. The crystal structure of the precipitate was further analyzed by XRD.…”

Design and Electrochemical Study of Platinum-Based Nanomaterials for Sensitive Detection of Nitric Oxide in Biomedical Applications

“…This was accomplished by controlling the charge transfer between different metals, the local coordination environment, lattice strain, and surface element distribution, particularly toward enhancing their sensitivity and selectivity in contrast to their monometallic analogues, which is often referred to as synergistic effects between the two metals [61,62,63]. The fabrication of metal nanoparticles with graphene enables excellent electrocatalytic properties that lead to high NO sensitivity [23,40,41,64].…”