Axial Chlorine Induced Electron Delocalization in Atomically Dispersed FeN4 Electrocatalyst for Oxygen Reduction Reaction with Improved Hydrogen Peroxide Tolerance

Highly efficient Fe-Cu dual-site nanoparticles supported on black pearls 2000 (carbon black) as oxygen reduction reaction catalysts for Al-air batteries

Acquiring cost-effective, high-performance, non-precious metal catalysts is crucial for substituting precious metal catalysts in the oxygen reduction reaction (ORR) to ensure sustainable energy conversion. Herein, we present a preparation strategy for a high-performance Cu-Fe-CN-3 electrocatalyst characterized via X-ray diffraction (XRD), Raman spectroscopy, Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) analyses. The results demonstrated that the incorporation of Cu and Fe into Black Pearls' carbon black (BP2000) and the strong synergistic effect between Fe and Cu contributed to the enhancement of active sites for the ORR. Electrochemical characterization revealed that the Cu-Fe-CN-3 catalyst synthesized by mixing Cu and Fe in a molar ratio of 3 : 1 exhibits superior catalytic activity for the ORR. The ORR performance of the Cu-Fe-CN-3 catalyst in an alkaline electrolyte (E1/2 0.867 V vs. RHE) surpassed that of Pt/C (E1/2 0.841 V vs. RHE), and the assembled aluminum-air battery demonstrated superior voltage stability compared to Pt/C under the same current density. After 2000 cycles, the E1/2 of the Cu-Fe-CN-3 catalyst exhibited a slight negative shift by 5 mV, which was better than the activity loss of the Pt/C catalyst (12 mV). At the same current density, the average discharge platform of Al-air batteries with the Cu-Fe-CN-3 catalyst was better than that of the commercial Pt/C catalyst. Therefore, the prepared Cu-Fe-CN-3 electrocatalyst exhibits great potential as an efficient ORR catalyst in fuel cells.

Non-noble metal single-atoms for oxygen electrocatalysis in rechargeable zinc-air batteries: recent developments and future perspectives

Ever-growing demands for zinc-air batteries (ZABs) call for the development of advanced electrocatalysts. Single-atom catalysts (SACs), particularly those for isolating non-noble metals (NBMs), are attracting great interest due to their merits of low cost, high atom utilization efficiency, structural tunability, and extraordinary activity. Rational design of advanced NBM SACs relies heavily on an in-depth understanding of reaction mechanisms. To gain a better understanding of the reaction mechanisms of oxygen electrocatalysis in ZABs and guide the design and optimization of more efficient NBM SACs, we herein organize a comprehensive review by summarizing the fundamental concepts in the field of ZABs and the recent advances in the reported NBM SACs. Moreover, the selection of NBM elements and supports of SACs and some effective strategies for enhancing the electrochemical performance of ZABs are illustrated in detail. Finally, the challenges and future direction in this field of ZABs are also discussed.

Synergistic Electronic Interaction of Nitrogen Coordinated Fe-Sn Double-Atom Sites: An Efficient Electrocatalyst for Oxygen Reduction Reaction

Double-atom site catalysts (DASs) have emerged as a recent trend in the oxygen reduction reaction (ORR), thereby modifying the intermediate adsorption energies and increasing the activity. However, the lack of an efficient dual atom site to improve activity and durability has limited these catalysts from widespread application. Herein, the nitrogen-coordinated iron and tin-based DASs (Fe-Sn-N/C) catalyst are synthesized for ORR. This catalyst has a high activity with ORR half-wave potentials (E1/2 ) of 0.92 V in alkaline, which is higher than those of the state-of-the-art Pt/C (E1/2  = 0.83 V), Fe-N/C (E1/2  = 0.83 V), and Sn-N/C (E1/2  = 0.77 V). Scanning electron transmission microscopy analysis confirmed the atomically distributed Fe and Sn sites on the N-doped carbon network. X-ray absorption spectroscopy analysis revealed the charge transfer between Fe and Sn. Both experimental and theoretical results indicate that the Sn with Fe-NC (Fe-Sn-N/C) induces charge redistribution, weakening the binding strength of oxygenated intermediates and leading to improved ORR activity. This study provides the synergistic effects of DASs catalysts and addresses the impacts of P-block elements on d-block transition metals in ORR.