Fabrication of Highly Stable Metal Oxide Hollow Nanospheres and Their Catalytic Activity toward 4-Nitrophenol Reduction

Abstract

In this paper, hollow nanospheres (HNSs) of metal oxides (NiO, CuO, and NiO/CuO) coated with a porous carbon shell (HNSs@C) with good structural stability were successfully prepared on the basis of the nanoscale Kirkendall effect. The formation process was based on a template-free method, and the as-prepared HNSs@C are very clean compared with products of the template process. In addition, the results of N adsorption-desorption noted that both the metal oxide HNSs and the coated carbon were mesoporous structures. Therefore, small molecules can access the inner space of the whole HNSs@C, which was expected to increase the active site area and to show better performances in applied fields, such as catalysts and sensors. As an example of the functional properties, the obtained HNSs@C were investigated as the catalyst for the hydrogenation of 4-nitrophenol (4-NP) and manifested highly catalytic activity and excellent stability. This work has opened up a novel route for the development of metal oxide HNSs nanocatalysts. This straightforward method is of significance for development of clean metal oxide HNSs with high stability and multiplied applications.

Functionalization of Hollow Nanomaterials for Catalytic Applications: Nanoreactor Construction

“…Owing to accessible highly active sites at both interior and exterior surfaces, the as‐obtained bimetallic dendritic nanocages showed 5.3 times higher activity than Pt black for anodic methanol oxidation reaction (MOR) of the direct methanol fuel cells. For mixed metal oxides, enhanced catalytic activity and stability for the hydrogenation of 4‑nitrophenol reduction were observed on NiO/CuO hollow nanospheres within porous carbon shell, as reported by Wu et al In terms of a generalized concept, cross‐connection of tortuous 1D nanowires to construct robust 3D porous nanomaterials provides hollow nanocatalysts with another effective structural functionalization strategy. Noble metal based nanoframeworks and spongy nanoporous are the representative examples, especially as high‐performance electrochemical nanocatalysts.…”

Facile Fabrication of Highly Active Magnetic Aminoclay Supported Palladium Nanoparticles for the Room Temperature Catalytic Reduction of Nitrophenol and Nitroanilines

“…To start with, 4-NP was added into deionized water; after sonication for about 15 min, the color of solution was light yellow and the UV−vis spectrum showed an absorption peak centered at 318 nm. After the addition of excess NaBH 4 (1.2 M, 0.25 mL), the color of the above mixed solution changed from light yellow to dark yellow and the UV-vis absorption spectrum of the 4-nitrophenolate salt exhibited a characteristic peak produced by the nitro compound at about 400 nm ( Figure 5 a) [ 32 , 33 ].…”

Enhancing the catalytic activity of recyclable nanocrystalline NiFe2O4 by replacing Ni by Cu

“…In this direction, constant research efforts are in progress to develop a most capable catalyst for the conversion from the toxic nitrophenols to value added aminophenols under mild reaction conditions. So far, wide range of catalysts such as metal oxides [5], highly expensive metal nanoparticles such as Pd, Ag, Au, Pt [6][7][8][9] and composite materials [10,11] have been developed for the reduction or degradation of nitrophenols. In recent times, magnetic nanomaterials, particularly spinel-type ferrite systems, are being studied as suitable alternative catalysts to drive the reduction of 4-nitrophenol to 4-aminophenol in aqueous medium [12][13][14][15].…”