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Spinel oxides, e.g., NiCo 2 O 4 , is a promising catalyst for the catalytic oxidation of toluene. Understanding and designing versatile NiCo 2 O 4 spinel is important for low-temperature toluene oxidation. Here, we investigated the surface-characteristic-dependent degradation activity of NiCo 2 O 4 crystals through experiment and characterization. NiCo 2 O 4 nanosheet using ethanol as solvent (named E--NiCo 2 O 4 ) exposing {110} crystal planes exhibited the lowest temperature toluene oxidation. The T 99 of toluene conversion was 256 °C, which is much lower than that of NiCo 2 O 4 nanosheet using ethylene glycol as solvent (named EG--NiCo 2 O 4 ), NiCo 2 O 4 octahedron (named O--NiCo 2 O 4 ) and NiCo 2 O 4 truncated octahedron (named TO--NiCo 2 O 4 ). Characterization using various techniques such as XRD, TEM, BET, XPS, H 2 -TPR and CO 2 -TPD showed that Co 3+ and surface adsorbed oxygen (O sur ) enriched surface, excellent redox properties and effective diffusion of the reaction product reasonably explain the enhancement in catalytic activity over the E--NiCo 2 O 4 . The research reveals that the effect of specific crystal planes and solvent was the key factor to govern the activity of low-temperature toluene oxidation., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

In order to study their synergistic catalytic effects in toluene degradation, CuMn 2 O 4 /HTS-1 (HTS-1 was a titanium silicon molecular sieve), Cu 0.7 Mn 2 Y 0.3 O x /HTS-1 and Cu 0.7 Mn 2 Ce 0.3 O x /HTS-1 catalysts were prepared by the impregnation method. The textural properties, redox properties and acidity of the catalysts were characterized by X-ray diffractometer (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), H 2 temperature-programmed reduction (H 2 -TPR), X-ray photoelectron spectroscopy (XPS), frustrated total internal reflection (FT-IR), ammonium temperature-programmed desorption (NH 3 -TPD) and pyridine adsorption internal reflection (Py-IR) measurements. The potential roles of Lewis acid sites (activating dioxygen) were discussed, and the experimental results indicated that the most efficient route for toluene degradation over Cu 0.7 Mn 2 Ce 0.3 O x /HTS-1 (toluene conversion rate of 90% (T 99 )=295°C) was ascribed to regulation of the synergistic effects of redox properties (activating molecular toluene) and Lewis acid sites (activating dioxygen). The Mars-Van-Krevelen (MVK) model was adopted to describe the reaction process of toluene oxidation, which gave an in-depth view into the toluene degradation over CuMn 2 O 4 /HTS-1, Cu 0.7 Mn 2 Y 0.3 O x /HTS-1 and Cu 0.7 Mn 2 Ce 0.3 O x /HTS-1. In addition, the synergistic effects between redox properties and Lewis acid sites were studied in detail., (Copyright © 2019. Published by Elsevier B.V.)

Abstract: A simple and novel method to fill carbon nanotubes (CNTs) with Ni–Fe alloys by methylbenzene-oriented constant current electrodeposition is demonstrated. The method is based on the difference in the surface conductivity of CNTs inside and outside in electrodeposition process owing to the covering of methylbenzene. The Ni–Fe alloys filled multiwalled carbon nanotubes (MWCNTs) were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and atomic absorption spectroscopy (AAS), respectively. Then the Ni–Fe alloys filled MWCNTs were used as hydrazine oxidation electrocatalysts in direct hydrazine (N2H4)-air fuel cells. Cyclic voltammograms (CVs) indicated that Ni85Fe15-filled MWCNTs had superior electrocatalytic activity for hydrazine electrocatalysis than catalysts with other compositions. [Copyright &y& Elsevier]