Co@Co₃O₄@PPD Core@bishell Nanoparticle‐Based Composite as an Efficient Electrocatalyst for Oxygen Reduction Reaction

Abstract

Durable electrocatalysts with high catalytic activity toward oxygen reduction reaction (ORR) are crucial to high-performance primary zinc-air batteries (ZnABs) and direct methanol fuel cells (DMFCs). An efficient composite electrocatalyst, Co@Co3 O4 core@shell nanoparticles (NPs) embedded in pyrolyzed polydopamine (PPD) is reported, i.e., in Co@Co3 O4 @PPD core@bishell structure, obtained via a three-step sequential process involving hydrothermal synthesis, high temperature calcination under nitrogen atmosphere, and gentle heating in air. With Co@Co3 O4 NPs encapsulated by ultrathin highly graphitized N-doped carbon, the catalyst exhibits excellent stability in aqueous alkaline solution over extended period and good tolerance to methanol crossover effect. The integration of N-doped graphitic carbon outer shell and ultrathin nanocrystalline Co3 O4 inner shell enable high ORR activity of the core@bishell NPs, as evidenced by ZnABs using catalyst of Co@Co3 O4 @PPD in air-cathode which delivers a stable voltage profile over 40 h at a discharge current density of as high as 20 mA cm(-2) .

Atomically Thin Mesoporous Co3O4 Layers Strongly Coupled with N‐rGO Nanosheets as High‐Performance Bifunctional Catalysts for 1D Knittable Zinc–Air Batteries

“…With d ‐spacing values of 0.243 and 0.285 nm, the lattice matches well with the (311) and the (220) planes of Co 3 O 4 , respectively. [11a,15a,17] This is further evidenced by the X‐ray diffraction (XRD) pattern in Figure S4 (Supporting Information). The TEM elemental mapping (Figure c) clearly shows uniform distribution of C, N, O, and Co throughout the hybrid nanosheets, indicating successful N‐doping and homogeneous distribution of Co 3 O 4 on the N‐rGO substrate.…”

“…This phenomenon has also been reported for other ultrathin inorganic materials and is attributed to the phonon confinement effect. [11c,20] Additionally, peaks at ≈1355 and ≈1595 cm −1 are identified for both N‐rGO and the hybrid nanosheets, corresponding to the D and G bands of carbonaceous material,[17a,19b] further demonstrating the coexistence of N‐rGO in the hybrid nanosheets illustrated by the TEM images. The content of Co 3 O 4 in the hybrid nanosheets is determined to be ≈63 wt% (Figure S7, Supporting Information) by thermal gravimetric analysis (TGA).…”

Tuning the Electronic Bandgap: An Efficient Way To Improve the Electrocatalytic Activity of Carbon‐Supported Co3O4 Nanocrystals for Oxygen Reduction Reactions

“…The oxygen reduction reaction (ORR) has attracted extensive attention in recent decades because it belongs to one of the most key reactions in renewable and clean‐energy technologies . However, owing to the sluggish kinetics and high overpotential in the ORR, the use of efficient electrocatalysts is required for its practical application in the above‐mentioned fields . Until now, of the published electrocatalysts available for ORR, spinel transition‐metal oxides, such as Co 3 O 4 , Mn 3 O 4 , and Fe 3 O 4 , have been regarded as promising alternatives to Pt catalysts because of their relatively high electrocatalytic activity, low cost, high earth abundance, and good durability .…”

“…[1][2][3][4] However,o wing to the sluggish kinetics and high overpotential in the ORR, the use of efficient electrocatalysts is required for its practical application in the above-mentioned fields. [5,6] Until now,o ft he published electrocatalysts available for ORR, spinel transition-metal oxides, such as Co 3 O 4 , [7,8] Mn 3 O 4 , [9,10] andF e 3 O 4 , [11,12] have been regarded as promising alternatives to Pt catalysts because of their relatively high electrocatalytic activity,l ow cost, high earth abundance, and good durability. [13][14][15][16] However,t he practical application of these spinel oxides as electrocatalystsf or the ORR has been hindered by their poor conductivity and low mass-specific activity.T oenhance their activity further, various approaches have been adopted to fabricate morphology-controlleds pinel oxidesw ith differento rientationsb ecause these preferred orientations can enhancethe electrochemical properties.…”

General and Scalable Fabrication of Core–Shell Metal Sulfides@C Anchored on 3D N‐Doped Foam toward Flexible Sodium Ion Batteries

“…Therefore, the deconvoluted peak appeared at 285.7 eV in the C 1s spectrum (Figure d) is assigned to SC bond. The N 1s spectrum (Figure e) can be divided into four characteristic peaks at BEs of 398.5 (pyridinic N, 54.9 at.%), 399.8 (pyrrolic N, 19.3 at.%), 400.9 (graphitic N, 17.6 at.%), and 402.5 (oxidized N, 8.2 at.%) eV . The first two kinds of N are usually regarded as metal‐coordination sites because of their lone‐pair electrons, and therefore the predominance of the two kinds of N can to a certain extent indirectly demonstrate the formation of CoN bonds .…”