Achieving highly practical capacitance of MnO₂ by using chain-like CoB alloy as support

Abstract

The practical performance of MnO2 as a capacitor material is limited mainly by its poor electronic conductivity. Arranging MnO2 on the conductive backbone to form a unique hierarchical nanostructure is an efficient way to enhance its capacitor performance. Herein, a hierarchically core-shell structure, in which thin γ-MnO2 sheets are grown on amorphous CoB alloy nano-chains (CoB@MnO2), is produced via a simple and scalable solution-phase procedure at room temperature. A specific capacitance of 612.0 F g-1 is obtained for the CoB@MnO2 capacitor electrode at a discharge current density of 0.5 A g-1, a value higher than those obtained for other conductive materials supported MnO2 electrodes reported in the literature. A rate retention value of 60.9% of its initial capacitance is obtained when the discharge current density increased by 12-fold. It is found that after 6000 charge-discharge cycles at 2 A g-1, the specific performance of CoB@MnO2 is 86.5%. The excellent capacitor performance of CoB@MnO2 is explained to be due to the hierarchical core-shell structure, in which the CoB alloy nano-chain backbone provides a transport pathway for the electron, and the porous MnO2 outer layers provide the channel for mass transfer, hence allowing further exposure to active sites. The combination of high capacitor performance and low-cost synthesis makes the core-shell CoB@MnO2 a promising cathode material for alkaline electrolyte supercapacitors.

Au Nanoparticles Anchored on Cobalt Boride Nanowire Arrays for the Electrochemical Determination of Prostate-Specific Antigen

“…of B 0 moves to a more positive direction, which is due to the electron-donating effects of B 0 ⃗ Co. The result is consistent with a previous report . The SEM image of AuNPs/CoB NWAs is shown in Figure I.…”

Interfacial Engineering in Crystalline Cobalt Tungstate/Amorphous Cobalt Boride Heterogeneous Nanostructures for Enhanced Electrochemical Performances

“…The Co−B state in B 1s XPS of B2 disappears apparently, which may be due to the inhibitory effect of the CoWO 4 signal on Co−B. 24 From Figure 1d, the core level spectrum of Co 2p outlines the Co 2p 3/2 and Co 2p 1/2 peaks at the bound energies of 779.3 (778.8) and 794.2 (795.09) eV, respectively. There are also two satellite peaks located at 782.84 (783.2) and 800.1 (801.2) eV, but the corresponding position of the three peaks of B2 sample shifted to higher binding energy compared with Co−B, which may indicate that the introduction of WO 4 2− increased the electropositivity of Co, accompanied by a redistribution of electron density.…”

“…23 Yan et al grew γ-MnO 2 flakes on the Co−B alloy nanochains via an extensible solution-phase process, where the Co−B alloy nanochains provided a transmission path for electrons. 24 The specific capacitance of the synthetic Co−B@MnO 2 electrode at 0.5 A g −1 was 612.0 F g −1 . Based on these references, transition metal borides can activate fast redox reactions to realize electronic tuning which may inspire the development of their derivatives of energy storage devices.…”

Crystalline Co2V3O8@Amorphous Co−B Core‐Shell Nano‐Microsphere: Tunable Shell Layer Thickness, Faradaic Pseudocapacitive Mechanism, and Electrochemical Capacitor Applications

“…For Co 3 V 2 O 8 @Co−B‐2, the B 1s spectrum consists of a peak at 192.6 eV. The obvious fading of the Co−B bond peak is possibly due to the inhibitory effect of the Co 3 V 2 O 8 signal on Co−B [45] …”