Mo-V-O Based Electrocatalysts for Low Temperature Alcohol Oxidation

Abstract

There is a growing interest in alcohol oxidation electrochemistry due to its role in renewable energy technologies. The goal of this work was to develop active non-precious metal electrocatalysts based on the Mo-V-(M)-O (M is Nb, Te) lattice. Selective gaseous alkane oxidation had been previously observed on these catalysts at elevated temperatures above 300°C. In this study, the activity of the catalysts at lower temperatures, 25−60°C, was investigated. Hydrothermal conditions were used to synthesize the Mo-V-(M)-O mixed oxides. Physical characterization of the catalysts were obtained by powder X-ray diffraction (XRD), scanning electron micrography (SEM) equipped with energy dispersive X-ray (EDX), transmission electron micrography (TEM), and X-ray photoelectron spectroscopy (XPS). The catalytic activity for the oxidation of cyclohexanol was studied electrochemically. Chronoamperometric studies were used to evaluate the long-term performance of the catalysts. The onset of alcohol oxidative current was observed between 0.2 and 0.6 V versus Ag/AgCl. Gas chromatography−mass spectrometry analysis was used to determine the nature of the oxidative products. The mild oxidation products, cyclohexanone and cyclohexene, were observed after oxidation at 60°C. The catalytic activity increased in the order Mo-V-O < Mo-V-Te-O < Mo-V-Te-Nb-O. Mo-V-(Te,Nb)-O based electrocatalysts efficiently catalyzed the oxidation of alcohols at low temperatures.

Facile sub-/supercritical water synthesis of nanoflake MoVTeNbOx-mixed metal oxides without post-heat treatment and their catalytic performance

“…[3][4][5][6][7] Among them, slurry and hydrothermal methods are the most common options; however, both of the processes need long reaction times that can take dozens of hours. [8][9][10] Furthermore, in order to improve the crystallinity and stability of products, a necessary post-heat treatment at 550-600 C under a given atmosphere, lasting for several hours, is also involved in current routes. For instance, Ueda et al 5 synthesized three Mo-V-O based oxides with single crystals by using a hydrothermal method at 175 C for 48 h followed by calcination under nitrogen atmosphere for 2 h at 600 C. Mazloom et al prepared MoVTeNbO x using a slurry method, in which continuous evaporation at 60 C was needed, rstly to remove the water in the precursor solution and a subsequent calcination at 600 C for 2 h under nitrogen atmosphere was then carried out.…”