3D Hollow Hierarchical Porous Carbon with Fe‐N₄‐OH Single‐Atom Sites for High‐Performance Zn‐Air Batteries

Abstract

The development of innovative and efficient Fe‐N‐C catalysts is crucial for the widespread application of zinc‐air batteries (ZABs), where the inherent oxygen reduction reaction (ORR) activity of Fe single‐atom sites needs to be optimized to meet the practical application. Herein, a three‐dimensional (3D) hollow hierarchical porous electrocatalyst (ZIF8@FePMPDA‐920) rich in asymmetric Fe‐N4‐OH moieties as the single atomic sites is reported. The Fe center is in a penta‐coordinated geometry with four N atoms and one O atom to form Fe‐N4‐OH configuration. Compared to conventional Fe‐N4 configuration, this unique structure can weaken the adsorption of intermediates by reducing the electron density of the Fe center for oxygen binding, which decreases the energy barrier of the rate‐determining steps (RDS) to accelerate the ORR and oxygen evolution reaction (OER) processes for ZABs. The rechargeable liquid ZABs (LZABs) equipped with ZIF8@FePMPDA‐920 display a high power density of 123.11 mW cm−2 and a long cycle life (300 h). The relevant flexible all‐solid‐state ZABs (FASSZABs) also display outstanding foldability and cyclical stability. This work provides a new perspective for the structural design of single‐atom catalysts in the energy conversion and storage areas.

Atomically Dispersed Dual-Metal ORR Catalyst with Hierarchical Porous Structure for Zn–Air Batteries

“…It can be concluded that the bimetal doped method can increase the defect degree of the catalyst, which can help adsorb oxygen and promote ORR. 40 BET test is usually used to analyze the pore structure of the catalyst. Figure 2c,d shows the nitrogen adsorption−desorption curves and pore size distributions of the three catalysts, respectively.…”

“…By comparing the I D / I G values of the three samples, FeNi-NPC-1000 (1.11) has the highest defect degree compared to those of Fe-NPC-1000 (1.09) and Ni-NPC-1000 (0.995). It can be concluded that the bimetal doped method can increase the defect degree of the catalyst, which can help adsorb oxygen and promote ORR . BET test is usually used to analyze the pore structure of the catalyst.…”

Regulating the Local Microenvironment of an Fe−N4 Single-Atom Catalyst for Enhanced Oxygen Reduction Reaction

“…Notably, ORR and ZAB performances of Fe-SA/NSC also approach the best levels observed in these reported Fe-based catalysts (Figure f and Table S5). ,,− …”

FeN3S1─OH Single‐Atom Sites Anchored on Hollow Porous Carbon for Highly Efficient pH‐Universal Oxygen Reduction Reaction

“…[12] The electronic structure of the central metal atom is adjusted by the axial coordination of the OH groups, which could optimize the adsorption-free energy of the Fe center, reducing the H 2 O 2 yield of ORR, and thereby improving the stability of the Fe-N-C catalyst. [13] However, it is difficult to achieve an outstanding improvement in ORR performance by introducing solely oxygen-containing functional groups. In addition, a new asymmetric planar tetra-coordinated configuration is also rebuilt by extra heteroatoms (B, S, P, etc.)…”