Zn, Co, and Fe Tridoped N–C Core–Shell Nanocages as the High-Efficiency Oxygen Reduction Reaction Electrocatalyst in Zinc–Air Batteries

Abstract

Transition metal–nitrogen–carbon (TM–N–C) nanomaterials are promising platinum-based substitutes for the oxygen reduction reaction (ORR). However, large-scale commercial production of high-efficiency, durable TM–N–C catalysts remains a formidable challenge. In this work, a facile ″ZIF-on-ZIF″ strategy is first adopted to design ZIF-8@ZIF-67 core–shell polyhedral nanocages, and then, ferrocene (Fc) is added to form ZIF-8@ZIF-67@Fc double-layer encapsulating polyhedral nanocages. Finally, Zn, Co, and Fe tridoped N–C nanocages (ZnCoFe–N–C) as the high-efficiency ORR electrocatalyst are prepared through high-temperature annealing. Benefiting from the trimetal, nitrogen and carbon species bond to each other to form highly efficient active sites, and the material exhibits outstanding performance in 0.1 M KOH, onset potential and half-wave potential of up to 0.95 and 0.878 V (vs RHE), respectively, and long-term durability and methanol tolerance. Furthermore, when utilizing as a zinc–air battery (ZAB) air electrode, it exhibits wonderful indicators, reflected in an open circuit voltage of 1.525 V, power density of 350.2 mW cm–2, and specific capacity of 794.7 mAh gzn –1, which outperforms the benchmark Pt/C catalyst. This work provides a facile and effective strategy to obtain a highly efficient and stable TM–N–C electrocatalyst for the ORR in ZABs.

Design and Facile Synthesis of Highly Efficient and Durable Bifunctional Oxygen Electrocatalyst Fe–Nx/C Nanocages for Rechargeable Zinc-Air Batteries

“…26 The HRTEM image of Fe−N x /C showed two types of lattice plane distances coexist, corresponding to the 0.206 and 0.17 nm lattice distances of metallic FeC x and Fe, respectively (Figure 2d). 27,28 Simultaneously, the 0.34 nm lattice spacing both exhibited in the outer and inner shell, which is attributed to the graphitized carbon (002) in Figure 2e. The HAADF-TEM image and corresponding C, N, and Fe element mapping images in Figure 2f−i showed that the distribution of these three elements were relatively uniform.…”

Hollow Carbon Sphere and Polyhedral Carbon Composites Supported Iron Nanoparticles as Excellent Bifunctional Electrocatalysts of Zn–Air Battery

“…The magnified areas in Figure 3 show that the Fe particles are wrapped by graphitic carbon and present distinct dotted stripes with the fringe spacing of 0.18 nm, corresponding to the (110) plane of Fe (Figure 3e). [ 50 ] To further explore the porosity structure of the samples, nitrogen adsorption isotherm data of Fe‐NC, NHCS@Fe, and Fe‐NC@NHCS‐600 were measured, as illustrated in Figure 4 . All three samples exhibit the type IV isotherm curves with obvious hysteresis loops, indicating their typical mesoporous structures, which is also consistent with the result of Figure 4b.…”

Defect‐Engineered Co3O4@Nitrogen‐Deficient Graphitic Carbon Nitride as an Efficient Bifunctional Electrocatalyst for High‐Performance Metal‐Air Batteries

“…[8] Metal-organic-frameworks (MOFs) [9] comprising metal ions and multi-element organic ligands represent one of the ideal precursors for the synthesis of T-N-C because of their inherent large specific surface area, ordered structure, and abundant contents of metal, carbon, and nitrogen. [10] For instance, Wang et al [11] developed a facile "ZIF-on-ZIF" strategy to craft Zn, Co, and Fe tri-doped N-C nanocage (ZnCoFe-N-C) catalysts through…”

“…[ 10 ] For instance, Wang et al. [ 11 ] developed a facile “ZIF‐on‐ZIF” strategy to craft Zn, Co, and Fe tri‐doped N–C nanocage (ZnCoFe‐N‐C) catalysts through high‐temperature annealing. The polyhedral porous structure, synergetic interaction of three metal components, and the coordination between the metals and nitrogen (TM–N x ) facilitated the overall catalytic performance.…”