Silver Doped Amorphous MnO₂ as Electrocatalysts for Oxygen Reduction Reaction in Al-Air Battery

Abstract

Manganese dioxide is a low-cost catalyst for oxygen reduction reaction (ORR) in alkaline media. In this paper, the amorphous MnO2 (AMO) was prepared, its characteristics and the effects of mixed with carbon nanotubes (CNTs), doped with silver nanoparticles on catalytic performance were investigated. The experimental results show that the performance of the AMO is slightly worse than that of the β-MnO2, which is possibly caused by the absence of the high catalytic activity (110) surface in the amorphous state. However, the addition of carbon nanotubes significantly improves the catalytic properties of AMO. Furthermore, the nanoscale silver particles doped AMO was prepared and characterized, and it is shown that the AMO/CNTs catalyst with 10 wt% Ag nanoparticles owns the best catalytic performance. Quantum chemical calculation on the ligand effect by electron structure shows that the interaction between Ag and Mn can shift the d-band center of Ag and lower the activation barrier of the O–O bond fracture, while Ag can low the adsorption of O2 for Mn. However, when the Ag content in MnO2 up to 20%, the adsorption will be weakened and the break kinetics of O–O bond will be reduced, which leads to the catalytic effect reduced.

Highly efficient Ag doped δ-MnO2 decorated graphene: Comparison and application in electrochemical detection of H2O2

“…It is notable that aggregation of Ag NPs was decreased in Ag@δ-MnO 2 /G than Ag/G. Furthermore, particle size of Ag NPs was smaller in Ag@δ-MnO 2 /G than Ag/G, which suggests the doping of Ag on δ-MnO 2 /G surface [34] . For the confirmation of doping of Ag on δ-MnO 2 /G surface, magnified HRTEM images were analyzed also.…”

“…The δ-MnO 2 /G surface could play a synergistic effect for the uniform distribution and effective size and shape of Ag NPs [31] . According to quantum chemical calculation, Mn doped can weaken the O–O bond and improve Ag catalysis performance, and Ag doped can enhance the adsorption of O 2 by MnO 2 [34] .…”

Construction of MWNT supported ultra-small Ag@MnO2 nanoparticles for the ORR and Al–air batteries

“…At the same time, Mn can improve the D-band center of Ag and enhance the O-O bond fracture kinetics, and Ag can improve the adsorption of O 2 on Mn, resulting in excellent catalytic performance, rate performance, and stability of the catalyst. 25 Meanwhile, the ORR properties of 20 wt% Pt/C, Ag/MWNTs, Ag@MnO 2 /MWNTs and MnO 2 /MWNTs were investigated by RDE experiments in O 2 saturated 0.1 M KOH solution. The catalytic activity of the ORR was characterized by the onset potential (E on-set ) and half-wave potential (E 1/2 ), dened as the potential at 5% and 50% of the diffusion-limiting current density, respectively.…”

Electrochemical Synthesis of an Organometallic Material Based on Polypyrrole/MnO2 as High-Performance Cathode

“…As an example, efficient MnO2-based electrocatalysts have been synthesized for ORR, such as multi-walled MnO2/PPy/MnO2 nanotubes [39], or α-MnO2 nanowires prepared in the presence of an ionic liquid as structure-directing agent [73], able to generate current densities closed to 7 mA.cm -2 . The introduction of nanoparticles into MnO2 materials has enable ORR to be boosted with delivered current densities close to 6 mA.cm -2 , such as example with Ag in amorphous MnO2 mixed with carbon nanotubes [74], or with Co3O4 attached to the surface of MnO2 nanorods [75].…”