Micro-sized ZIF-67 crystals were prepared and used as the reinforcing material to design novel paraffin-based composite phase change materials with a polymethyl methacrylate shell.
The
discovery of affordable and high-activity air electrodes for
the oxygen reduction reaction (ORR) in a Zn–air battery is
a key step toward its widespread application. Herein, we report cerium
doped lanthanum manganese perovskite La1–x
Ce
x
MnO3 (LCMx, x = 0, 0.05, 0.10, and 0.15) as an ORR
electrocatalyst of a Zn–air battery. The phase structure, morphology,
valence state, and oxygen desorption capability of synthesized LCMx were systematically investigated. The electrocatalytic
activities toward the ORR were studied using the rotating disk electrode
test and Zn–air battery technique. The results proved that
the proper substitution of La with Ce could efficaciously enhance
the ORR performance of LaMnO3 perovskite. La0.9Ce0.1MnO3 exhibited the most excellent activity
toward the ORR with a favorable current density of 5.94 mA cm–2, which could be ascribed to the regulation of Mn
valence states, abundant surface oxygen species, and high oxygen adsorption
capability. With La0.9Ce0.1MnO3 as
the air electrode catalyst, the Zn–air battery delivered a
peak power density of 124.48 mW cm–2 at 0.65 V.
This work reveals that cerium doping into the A-site of LaMnO3 perovskite is a feasible way to ameliorate its ORR catalytic
activity in a Zn–air battery.
For an ideal electrocatalyst for Zn-air batteries (ZABs) air electrode, it should possess efficient dual-functional catalytic activity for both oxygen reduction and oxygen evolution reactions in an alkaline electrolyte. Although LaMnO 3 perovskite oxide presents excellent ORR catalytic activity, its OER activity is inadequate to serve as a dual-functional catalyst for ZABs. To enhance the OER activity of LaMnO 3 perovskite, this work used a simple and easy-to-operate ultrasonic mixing technique to prepare the LaMnO 3 −CoO composite. The enhancement of OER and ORR catalytic activity of LaMnO 3 perovskite by CoO was investigated. Meanwhile, the cycling stability and polarization behavior of the assembled ZABs using LaMnO 3 −CoO composite as an air electrode were further evaluated. The battery delivered a maximum power density of 101.48 mW cm −2 and a high energy efficiency of up to 58.6% after 150 cycles. The LaMnO 3 −CoO composite exhibited better cycling stability than commercial Pt/C catalyst, which indicates that the LaMnO 3 −CoO composite is a promising dual-functional catalyst and can be applied in commercial Zn-air battery with an effective electrocatalytic activity.
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