Magnetic N-doped Co–carbon composites derived from metal organic frameworks as highly efficient catalysts for p-nitrophenol reduction reaction

Abstract

Magnetic nitrogenous cobalt-carbon composites were synthesized via calcination of N-ZIF-67, where metal and N atoms were introduced into the conductive carbon matrix formed during carbonization of N-ZIF-67, and were applied, as catalysts, in the reduction reaction of p-nitrophenol, assisted by NaBH. Characterization of the prepared composites was carefully performed using SEM, TEM, XRD, SQUID magnetometric analysis, XPS and nitrogen adsorption/desorption measurements. Compared to Co@C, which was similarly prepared, the N-Co@C catalyst exhibits much better catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol. The pseudo-first-order rate constant for the N-Co@C catalyst is 4.47 times greater than that for the Co@C catalyst, and its stability shows little change after five reaction cycles. The superior catalytic properties of the N-Co@C catalyst are due to the presence of N moieties. Leaching out the cobalt cores was induced using FeCl and HCl to see what the active centers were. The results show that the majority of the catalytic activity is associated with the metal cores.

Hollow N‐ZIFs@NiCo‐LDH as highly efficient catalysts for 4‐nitrophenol and dyes

“…On the other hand, graphitic N can also increase the electronic density of carbon atoms and the electronic transmission ability of catalysts was improved, increasing the catalytic activity of samples. [4,20,36] Therefore, the results indicate the importance of the graphitic N concentration of the three catalysts in the comparison of the rate of the catalytic reaction which matched well with the XPS results. A comparison of the catalytic activity between the N-ZIFs@NiCo-LDH composites and various previously reported catalysts in the reduction of 4-NP is presented in Table 1.…”

“…Besides, exposure to 4-NP can cause harm to the nervous system, viscera and blood of humans and animals, which makes it is meaningful and urgent to treat 4-NP in industrial and agricultural wastewater. [4] There are many methods that have been used to deal with 4-NP, such as Fenton oxidation reaction adsorption, [5] chemical oxidation, [6] microbial degradation [7] and photocatalysis. [8] However, the high operation cost, low production efficiency and long operation time prevent these methods from being applied in practical applications.…”

Synthesis of a Magnetic 2D Co@NC-600 Material by Designing a MOF Precursor for Efficient Catalytic Reduction of Water Pollutants

“…Among them, 4-NP is the most difficult organic pollutant to treat. − Conventional water purification treatment cannot effectively remove it because of it is highly water soluble. 4NP has a strong irritating effect on the skin, which can inhibit the central nervous system or damage liver and kidney functions on entering the body. − At present, a large number of physical and chemical methods are used to remove pollutants in wastewater, such as electrochemical degradation, photolysis, adsorption, and catalysis. − Reducing 4-NP to 4-AP is a good way to deal with the pollution because 4-AP is a precursor material for many industrial syntheses, such as picture developers used in the dye industry, corrosion inhibitors, and the manufacture of antipyretics and analgesics. − With the assistance of a catalyst, the reduction of 4-NP hydrogenation directly to 4-AP through NaBH 4 has received widespread attention. − Precious-metal catalysts which have excellent catalytic effects such as Au, Ag, and Pd have been widely reported for treating water pollutants, but they are extremely rare and expensive, which have limited their applications in real life. − In the catalytic reduction of 4-NP, the most important aspect is to find a non-precious-metal catalyst which has high activity and recyclability. Transition metals, for instance Fe, Co, and Ni, have been widely used in catalysis and many other fields in recent years due to their low price and good physicochemical properties. , However, the transition-metal particles can easily aggregate due to their high surface energy, which reduces their activity.…”

Hollow S‐ZIF‐(1:2.5)@NixSy as Highly Efficient Catalyst for 4‐Nitrophenol and Dye Reduction

“…Nevertheless, the time required for the degradation of 4‐NP is gradually extended, which may be attributed to the loss of some catalysts and the occupation of some active sites by‐products during the separation process. The experimental results illustrate that the prepared S‐ZIF‐(1:2.5)@Ni x S y catalyst is capable of excellent catalytic stability and recyclability …”