Temperature Effect on the Topotatic Synthesis of Spinel MnCoO Nanoparticles for Efficient Oxygen Reduction Electrocatalyst

Abstract

In this study, we demonstrated the temperature effect of our previously developed topotatic catalysis for the formation of Mn 0.005 Co 2.995 O 4 (MnCoO) spinel nanoparticles. Topotatic catalysis induces spinel MnCoO nanoparticles through the redox reaction of the metal cation (Co 2+ and Mn 2+ ) on the Co(OH) 2 nanosheet surface, acting as a growth template. This study particularly elucidates the temperature effect on spinel MnCoO nanoparticles' size, morphology, and crystallinity based on their electrocatalytic performance in an oxygen reduction reaction (ORR). We found that lower temperature produces an amorphous phase, whereas higher temperature induces a large aggregate. We obtained the monodispersed MnCoO nanocubes at approximately 90 C, exhibiting the best ORR performance with an electron-transfer number of 3.86.

Porous spinel-type transition metal oxide nanostructures as emergent electrocatalysts for oxygen reduction reactions

“…102 The effect of temperature (70, 90, 120 and 150 °C) on the sizes and morphology of MnCoO was investigated for the ORR. 103 MnCoO-90 NCs possessed superior ORR kinetics compared with E onset , E 1/2 and J L (−0.18 V; −0.25 V vs. Ag/AgCl; 5.3 mA cm −2 ), while MnCoO-70, MnCoO-120 and MnCoO-150 had an E onset in the range −0.20 to −0.22 V vs. Ag/ AgCl, and an E 1/2 of −0.28 to −0.29 V vs. Ag/AgCl. The ideal particle sizes and high ECSA bequeathed the MnCoO-90 NCs with a superior ORR.…”

Excess dopant effect in platinum‐based alloys toward the oxygen electroreduction reaction

“…Among many ORR catalysts, Pt has been known as the best catalyst which can withstand the harsh conditions of ORR 13–16 . However, the scarcity and the high price of Pt are the main obstacles to PEMFC commercialization 17,18 . Pt‐based bimetallic alloys have been proposed as the solution to this concern by enhancing the activity while decreasing the Pt mass loading in the catalyst 19–22 .…”

“…[13][14][15][16] However, the scarcity and the high price of Pt are the main obstacles to PEMFC commercialization. 17,18 Pt-based bimetallic alloys have been proposed as the solution to this concern by enhancing the activity while decreasing the Pt mass loading in the catalyst. [19][20][21][22] Among various Pt bimetallic alloys, PtNi exhibited superior ORR performances.…”

Recent advances in the synthesis of layered double hydroxides nanosheets

“…13 In order to take the most advantage of nanolayer nature of LDH and to facilitate film fabrication, it is strongly required to obtain nanosheets of LDHs. In fact, various kinds of two-dimensional materials, including titanate, 14 metal oxide, [15][16][17] and metal chalcogenides [18][19][20] have been subjected to exfoliation for the easy materials process. However, the methods applied to materials mentioned above are not directly applied to LDH.…”