Interfacing Manganese Oxide and Cobalt in Porous Graphitic Carbon Polyhedrons Boosts Oxygen Electrocatalysis for Zn–Air Batteries

Abstract

Rational design and synthesis of highly active and robust bifunctional non‐noble electrocatalysts for both oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are urgently required for efficient rechargeable metal–air batteries. Herein, abundant MnO/Co heterointerfaces are engineered in porous graphitic carbon (MnO/Co/PGC) polyhedrons via a facile hydrothermal‐calcination route with a bimetal–organic framework as the precursor. The in situ generated Co nanocrystals not only create well‐defined heterointerfaces with high conductivity to overcome the poor OER activity but also promote the formation of robust graphitic carbon. Owing to the desired composition and formation of the heterostructures, the resulting MnO/Co/PGC exhibits superior activity and stability toward both OER and ORR, which makes it an efficient air cathode for the rechargeable Zn–air battery. Importantly, the homemade Zn–air battery is able to deliver excellent performance including a peak power density of 172 mW cm−2 and a specific capacity of 872 mAh g−1, as well as excellent cycling stability (350 cycles), outperforming commercial mixed Pt/C||RuO2 catalysts. This work highlights the synergy from heterointerfaces in oxygen electrocatalysis, thus providing a promising approach for advanced metal–air cathode materials.

Metal–Organic Frameworks Based Electrocatalysts for the Oxygen Reduction Reaction

“…For example, uniformly tunable pores in MOFs and mesoporous carbon wall in MOF derivatives can provide effective selectivity towards oxygen molecules but largely prevent crossover by contaminants . For long‐life rechargeable metal–air batteries, robust and bifunctional electrocatalysts should be aimed, which can be prepared by integrating the OER active sites and the ORR active sites in a single catalyst . Equally important, considerable efforts should be devoted to the fabrication of devices with different electrolytes for practical applications in the future …”

“…K) LSV curves for ORR of different samples recorded in O 2 ‐saturated 0.1 m KOH solution. L) Discharge polarization and power density curves and M) long‐term cycling performance of the home‐made ZAB (Inset is the photograph of a blue LED screen powered by two ZABs in series with MnO/Co/PGC as the air‐cathode) . Copyright 2019, Wiley‐VCH.…”

“…Most recently, Lu et al. engineered abundant MnO/Co heterointerfaces in porous graphitic carbon (MnO/Co/PGC) polyhedrons via one‐step pyrolysis of a bimetal–organic framework (Figure H) . After calcination, the MnO/Co/PGC polyhedrons possess a rough surface with a distinct graininess (Figure I).…”

“…engineered abundant MnO/Co heterointerfaces in porous graphitic carbon (MnO/Co/PGC) polyhedrons via one-step pyrolysis of ab imetal-organic framework ( Figure 9H). [117] After calcination, the MnO/Co/ PGC polyhedrons possess ar ough surface with ad istinct graininess ( Figure 9I). Theinsitu generated Co nanocrystals are uniformly distributed within porous graphitic carbon polyhedrons ( Figure 9J), creating well-defined heterointerfaces.O wing to the desired composition and formation of the heterostructures,t he resulting MnO/Co/PGC exhibits superior activity and stability towards ORR ( Figure 9K).…”

“…[122] Unlike this work using NaH 2 PO 2 as the phosphorus source,W ang et al selected aC u-based MOF containing phosphorus atoms and nitrogen atoms in the ligands as the single precursor and template to prepare novel Cu 3 PNPs coated by aN,P-codoped carbon shell. [126] Recently, Guan et al synthesized unique hybrid cobalt/cobalt nitride [117] Copyright2 019, Wiley-VCH. N) Schematic illustrationo fthe formation process, O) FESEM, and P) TEM images of Co-C@Co 9 S 8 DSNCs.…”