Rapid room-temperature synthesis of nanocrystalline spinels as oxygen reduction and evolution electrocatalysts

Abstract

Spinels can serve as alternative low-cost bifunctional electrocatalysts for oxygen reduction/evolution reactions (ORR/OER), which are the key barriers in various electrochemical devices such as metal-air batteries, fuel cells and electrolysers. However, conventional ceramic synthesis of crystalline spinels requires an elevated temperature, complicated procedures and prolonged heating time, and the resulting product exhibits limited electrocatalytic performance. It has been challenging to develop energy-saving, facile and rapid synthetic methodologies for highly active spinels. In this Article, we report the synthesis of nanocrystalline M(x)Mn(3-x)O(4) (M = divalent metals) spinels under ambient conditions and their electrocatalytic application. We show rapid and selective formation of tetragonal or cubic M(x)Mn(3-x)O(4) from the reduction of amorphous MnO(2) in aqueous M(2+) solution. The prepared Co(x)Mn(3-x)O(4) nanoparticles manifest considerable catalytic activity towards the ORR/OER as a result of their high surface areas and abundant defects. The newly discovered phase-dependent electrocatalytic ORR/OER characteristics of Co-Mn-O spinels are also interpreted by experiment and first-principle theoretical studies.

Recent Progress on Layered Double Hydroxides and Their Derivatives for Electrocatalytic Water Splitting

“…Electrocatalytic splitting water is regarded as one of the most convenient and promising strategies to produce hydrogen 13. Hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are two important half reactions of splitting water, which are both vital for its overall efficiency 14, 15.…”

Mn3O4@CoMn2O4–CoxOyNanoparticles: Partial Cation Exchange Synthesis and Electrocatalytic Properties toward the Oxygen Reduction and Evolution Reactions

“…(7)(8)(9)(10)(11)(12)(13)(14) Among transition metal oxides, Mn-based oxides and particularly spinels have shown outstanding performance for ORR and, to a minor extent, for OER. (7,(15)(16)(17)(18)(19)(20)(21) Besides, Co-based oxides are excellent electrocatalysts for OER, (22)(23)(24)(25) However, the multiple valence and related structural variability of transition metal oxides, which is at the origin of their exceptional electrocatalytic performance, is also behind the difficulty to produce these compounds in a reproducible and controlled manner.…”

Porous nanoarchitectures of spinel-type transition metal oxides for electrochemical energy storage systems

“…In these circumstances, the electrochemical energy storage systems (ESSs), such as lithium-ion batteries, [6][7][8][9][10] metal-air batteries, [11][12][13][14][15] electrochemical capacitors, [16][17][18][19][20] and redox flow batteries, [21][22][23][24][25] have attracted worldwide attention due to their promising energy storage capabilities (Fig. 1).…”