Synthesis of δ–MnO₂/Reduced Graphene Oxide Hybrid In Situ and Application in Mg–Air Battery

Abstract

Different forms of δ–MnO2 were constructed with their reduction sites anchored on non-support or other supports. Morphology, composition, and electrochemical properties of MnO2 and its hybrids were analyzed. Results revealed that MnO2/reduced graphene oxide (rGO) layered hybrid showed a higher BET surface area due to the synergistic effect on the introduction of rGO and the morphologic transformation of anchored MnO2. MnO2/rGO–2 exhibits a higher ratio of Mn3+: Mn4+ content, a better adsorption performance for O2, and a lower charge-transfer resistance when respect to pristine δ–MnO2. Compared with other MnO2/rGO hybrids, porous MnO2/rGO-2 layered hybrid exhibits the best electrochemical property: a closer four-electron process (3.95), a more positive E onset (0.92 V vs RHE), and superior long-term durability (98.5% after 25,000 s). Especially, a mechanically reusable Mg–air battery with MnO2/rGO–2 cathode catalyst only exhibits a 5% decay for 264 h.

Approaches to construct high-performance Mg–air batteries: from mechanism to materials design

“…And the MnO 2 /rGO cathode exhibited excellent electrochemical performance: quasi-four electron process (3.95), positive onset potential (0.92 V vs. RHE), and excellent long-term durability (98.5% retention after 25000 s). 165…”

“…And the MnO 2 /rGO cathode exhibited excellent electrochemical performance: quasi-four electron process (3.95), positive onset potential (0.92 V vs. RHE), and excellent long-term durability (98.5% retention aer 25000 s). 165 Co-based materials are also another important type of cathode catalysts. 132,166,167 The hybrid of Co 3 O 4 and graphene This journal is © The Royal Society of Chemistry 2023 oxide (GO) exhibited surprisingly high activity for the ORR, even far exceeding Pt/C catalysts, even though these two ingredients showed minimal catalytic activity individually.…”

Layered Materials in the Magnesium Ion Batteries: Development History, Materials Structure, and Energy Storage Mechanism

“…Since then, more and more types of LMS have been used in MIBs. In 2013, the first application of WSe 2 as the Mg 2+ storage cathode was carried out by Shen et al [120] Following this, Taniguchi et al [121] and Mai et al [122] applied TiSe 2 and NbSe 2 as cathodes for MIBs, respectively. Up to now, there has been more literature on the application of LMS to MIBs, and many of them give interesting design optimization strategies for LMS electrode (Figure 5a).…”

“…In 2013, the first application of WSe 2 as the Mg 2+ storage cathode was carried out by Shen et al. [ 120 ] Following this, Taniguchi et al. [ 121 ] and Mai et al.…”

Heme-Based Composites as Cathode Catalysts for Lithium-Oxygen Batteries and Analysis of the Reaction Mechanism

“…24 The exploration of cathode materials that can successfully host heme catalysts is a must. Graphene, as a Sp2 carbon material, can provide a large specific surface area for the reaction on the one hand, 25 and on the other hand possesses a large number of free-flowing π electrons, which makes them potential catalysts for electron-demand reactions. However, these π-electrons are too inert to be used directly in ORR.…”