MnCo₂O₄ Preparation by Microwave-Assisted Route Synthesis (MARS) and the Effect of Carbon Admixture

Abstract

Catalyst spinel MnCo 2 O 4 with particle size <30 nm was prepared by a novel microwaveassisted route. To determine the optimal amount of carbon needed as a microwave susceptor, varying amounts of amorphous carbon powder (7-26 wt %) were mixed with the aqueous solutions of Mn-and Co-nitrates. After heat treatment at 200°C in a conventional oven, the mixtures were heat-treated in a microwave oven (2.45 GHz) at a power of 350 W. The effect of the carbon amount on the formation and properties of the catalysts was studied. In this production method, 13 wt % of carbon was found to be the minimum needed for spinel MnCo 2 O 4 formation. Most of the carbon was oxidized during the microwave treatment. When the carbon content in the nitrate-carbon mixture was increased beyond 13 wt %, the carbon content and the specific surface area of the final catalyst started to decrease. However, the carbon amount of 18 wt % in the initial nitrate-carbon mixture was found to be the most preferable when considering the catalytic activity of the spinel toward oxygen reduction reaction in alkaline electrolyte.

Nanostructured WCx/CNTs as highly efficient support of electrocatalysts with low Pt loading for oxygen reduction reaction

“…1,2 The oxygen reduction reaction (ORR) is an important electrochemical reaction involved in proton exchange membrane fuel cells. 3,4 However, the low reaction rate of the ORR and the prohibitive production cost in Pt-based electrocatalysts are the main problems. [5][6][7] Moreover, methanol crossover from the anode to the cathode leads to an extra loss in the overall efficiency of direct methanol fuel cells.…”

Temperature-controlled microwave solid-state synthesis of Li3V2(PO4)3 as cathode materials for lithium batteries

“…Microwave solid-state synthesis method has already been applied to synthesize a number of inorganic materials, such as carbides, nitrides, complex oxides, silicides, and zeolites, etc. [12][13][14][15][16][17][18][19]. Microwave solid-state synthesis method as a novel method has been developed to prepare cathode materials for lithium batteries [12][13][14][15]19].…”

The beneficial effect of the addition of tungsten carbides to Pt catalysts on the oxygen electroreduction

“…[1][2][3][4] From the catalytic point of view, the reaction mechanism on a Pt catalyst has attracted most attention because Pt and Pt-alloys are still the best catalysts for low-temperature fuel cells. 5,6 In contrast to hydrogen oxidation on Pt, which is a very fast reaction, oxygen reduction on Pt exhibits a slow and complicated kinetic behavior. The standard reversible potential for O 2 reduction is 1.23 V, but kinetic limitations for the oxygen reduction reaction (ORR) lead to cell voltage losses of at least 0.3 to 0.4 V under typical operating conditions, which is about 10 times larger than that for H 2 oxidation at an anode.…”