Key Takeaways & Executive Findings
- •• An alloying-degree control strategy successfully fabricates Co/Co7Fe3 heterojunctions on nitrogen-doped carbon spheres (CoFe@NCS), enabling tunable phase composition. • The optimal CoFe0.08@NCS catalyst exhibits excellent bifunctional activity: half-wave potential of 0.80 V for ORR and overpotential of 283 mV at 10 mA·cm−2 for OER. • In liquid-state zinc-air batteries, CoFe0.08@NCS achieves a high peak power density of 157 mW·cm−2 and stable voltage gap over 150 h, surpassing Pt/C+RuO2 benchmarks. • Solid-state flexible ZABs with CoFe0.08@NCS show reliable performance under various bending conditions, highlighting practical flexibility.
Abstract
Exploring efficient and nonprecious metal electrocatalysts of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is crucial for developing rechargeable zinc–air batteries (ZABs). Herein, an alloying-degree control strategy was employed to fabricate nitrogen-doped carbon sphere (NCS) decorated with dual-phase Co/Co7Fe3 heterojunctions (CoFe@NCS). The phase composition of materials has been adjusted by controlling the alloying degree. The optimal CoFe0.08@NCS electrocatalyst displays a half-wave potential of 0.80 V for ORR and an overpotential of 283 mV at 10 mA·cm−2 for OER in an alkaline electrolyte. The intriguing bifunctional electrocatalytic activity and durability is attributed to the hierarchically porous structure and interfacial electron coupling of highly-active Co7Fe3 alloy and metallic Co species. When the CoFe0.08@NCS material is used as air–cathode catalyst of rechargeable liquid-state zinc–air battery (ZAB), the device shows a high peak power-density (157 mW·cm−2) and maintains a stable voltage gap over 150 h, outperforming those of the benchmark (Pt/C+RuO2)-based device. In particular, the as-fabricated solid-state flexible ZAB delivers a reliable compatibility under different bending conditions. Our work provides a promising strategy to develop metal/alloy-based electrocatalysts for the application in renewable energy conversion technologies.
1. Introduction
Rechargeable Zn–air batteries (ZABs) have attracted much attention recently, owing to the highly theoretical energy density, environmental friendliness, and abundant manufacturing resources [1–2]. Nevertheless, the intrinsically sluggish kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) occurring on air cathode severely hinder the practical application of ZABs. Nowadays, precious metals (Pt- and Ru/Ir-based materials) are regarded as the state-of-the-art electrocatalysts for ORR and OER. However, the widespread and industrial application are limited by the prohibitive cost, scarcity, and inferior durability [3]. Thus, extensive research efforts have been focused on exploring highly-stable and cost-effective materials through engineering bifunctional oxygen functionalities on single electrocatalyst [4–5].
Transition-metal nanoparticles embedded nanocarbons have demonstrated superior electrocatalytic performances because of intriguing catalytic activity and inexpensiveness [6–7]. Unfortunately, single metals are not directly recognized as efficient electrocatalysts because of unsuitable adsorption energy for oxygen/intermediates [8]. Notably, alloys can precisely adjust the lattice size of transition metals [9], and meanwhile the formation of reasonable structure via alloying can regulate the d-band center, thereby optimizing the adsorption energy of reactants to promote the electrocatalytic activity [10]. Encouraging work has demonstrated that the inherently electrocatalytic activity could been further promoted by constructing single-metal/alloy heterointerfaces since the electronic coupling at interfaces is proficient in constructing catalytic surface favorable for reactants [11]. To date, the most used method for fabricating carbon supported metallic heterojunctions is a direct pyrolysis of mixtures including metal-containing compounds and carbon source [12]. However, it remains a challenge to optimize the morphology and structure of these systems.
In this study, an alloying-degree control strategy was employed to fabricate the sphere-like hybrids consisting of N-doped carbon spheres implanted with Co/Co7Fe3 heterojunctions (CoFe@NCS) (Fig. 1). Specifically, the polydopamine (PDA) spheres are used to functionalize Fe-incorporated Co-ZIFs and fabricate a series of CoFe-ZIF@PDA precursors. Being rich in catechol and amine groups, the binding of PDA to metal ions can promote the nucleation and in-situ growth of ZIFs nanocrystals [13]. Then, the CoFe@NCS nanocatalysts are obtained after pyrolyzing the CoFe-ZIF@PDA precursors. In the structure, the Co–Co7Fe3 interfaces are generated by incomplete alloying degree in the process of calcination via tuning the amount of Fe doping. The optimal CoFe0.08@NCS exhibits an intriguing bifunctional electrocatalytic activity and durability towards both OER and ORR, by virtue of interfacial coupling and hierarchical pore structure. Meanwhile, the as-assembled rechargeable zinc-air battery demonstrates superior performance.
Loading authentic research manuscript (Pages 1–5)...
Junkang Chen, Yongyue Zhuang, Yanxin Qiao, Yu Zhang, Aihua Yuan, Hu Zhou (2025). Co/Co7Fe3 heterostructures with controllable alloying degree on carbon spheres as bifunctional electrocatalyst for rechargeable zinc–air batteries. Int. Journal of Minerals, Metallurgy and Materials (矿物冶金与材料学报). https://doi.org/10.1007/s12613-024-2958-9
Research & Educational Purpose Only:The translations, structured abstracts, analytical annotations, and data reports provided by SinoTechIntel are intended exclusively for academic research, internal corporate R&D, and educational benchmarking. They do not constitute formal engineering, chemical safety, legal, or professional advice.
Copyright & Intellectual Property Notice: Original copyright of the underlying source articles and experimental data remains with the respective authors, institutions, and original publishing journals. SinoTechIntel claims intellectual property only over its proprietary translations, analytical syntheses, and AEO structured enhancements in accordance with international fair use and academic citation principles.
Frequently Asked Questions
What is the main innovation of this study?
The study introduces an alloying-degree control strategy to fabricate Co/Co7Fe3 heterojunctions on nitrogen-doped carbon spheres, enabling tunable phase composition and enhanced bifunctional electrocatalytic activity for oxygen reduction and evolution reactions.
What are the key performance metrics of the optimal CoFe0.08@NCS catalyst?
The optimal CoFe0.08@NCS catalyst exhibits a half-wave potential of 0.80 V for ORR and an overpotential of 283 mV at 10 mA·cm−2 for OER in alkaline electrolyte.
How does the CoFe0.08@NCS catalyst perform in zinc-air batteries?
In liquid-state zinc-air batteries, it achieves a high peak power density of 157 mW·cm−2 and maintains a stable voltage gap over 150 hours, outperforming the benchmark Pt/C+RuO2-based device. Solid-state flexible ZABs also show reliable performance under bending.
What is the significance of the alloying degree control?
Controlling the alloying degree allows precise adjustment of the phase composition, creating Co/Co7Fe3 heterojunctions that optimize interfacial electron coupling and catalytic activity, which is crucial for bifunctional performance.
What are the potential applications of this research?
The developed CoFe@NCS electrocatalysts are promising for renewable energy conversion technologies, particularly in rechargeable zinc-air batteries for both liquid and flexible solid-state devices.
Related Technical Papers & Translations
Direct Repair of the Crystal Structure and Coating Surface of Spent LiFePO4 Materials Enables Superfast Li-Ion Migration
The rapid accumulation of spent LiFePO4 (LFP) cathodes from retired lithium-ion batteries necessitates the development of effective and environmental-friendly recycling strategies. In this context, direct regeneration has emerged as a promising approach for reclaiming LFP cathode materials, offering a streamlined pathway to restore their electrochemical functionality. We report an integrated regeneration protocol that simultaneously repairs the degraded crystal structure and reconstructs the damaged carbon coating in spent LFP. The regenerated cathode material had superfast lithium-ion diffusion kinetics and a stable cathode–electrolyte interface, giving a remarkable rate capability with specific capacities of 122 mAh g−1 at 5C and 106 mAh g−1 at 10C (1C = 170 mA g−1). It also maintained capacities of 110.7 mAh g−1 (5C) and 84.1 mAh g−1 (10C) after 400 cycles. It could be used in harsh environments and could be stably cycled at subzero temperatures (−10 and −20 °C) and in solid-state electrolyte batteries. Life cycle assessment combined with economic evaluation using the EverBatt model reveals that this direct regeneration approach has high economic and environmental benefits.
Oxide Semiconductor for Advanced Memory Architectures: Atomic Layer Deposition, Key Requirement and Challenges
Oxide semiconductors (OSs), introduced by the Hosono group in the early 2000s, have evolved from display backplane materials to promising candidates for advanced memory and logic devices. The exceptionally low leakage current of OSs and compatibility with three-dimensional (3D) architectures have recently sparked renewed interest in their use in semiconductor applications. This review begins by exploring the unique material properties of OSs, which fundamentally originate from their distinct electronic band structure. Subsequently, we focus on atomic layer deposition (ALD), a core technique for growing excellent OS films, covering both basic and advanced processes compatible with 3D scaling. The basic surface reaction mechanisms—adsorption and reaction—and their roles in film growth are introduced. Furthermore, material design strategies, such as cation selection, crystallinity control, anion doping, and heterostructure engineering, are discussed. We also highlight challenges in memory applications, including contact resistance, hydrogen instability, and lack of p-type materials, and discuss the feasibility of ALD-grown OSs as potential solutions. Lastly, we provide an outlook on the role of ALD-grown OSs in memory technologies. This review bridges material fundamentals and device-level requirements, offering a comprehensive perspective on the potential of ALD-driven OSs for next-generation semiconductor memory devices.
Laser powder bed fusion of biodegradable Zn-4Cu alloy: Processing, microstructure and properties
Zn's natural degradability and biocompatibility make it a promising candidate for implants, however, its mechanical properties remain insufficient for bone applications. In this study, the performance of Zn was enhanced by developing Zn-Cu alloys via laser powder bed fusion (LPBF). Optimal LPBF parameters for forming stable tracks were achieved by adjusting laser power and scanning speed. Under optimized conditions of 100 W and 100 mm/s, high-density (99.58%) Zn-Cu alloys with improved hardness (68.2HV) and yield strength (160 MPa) were achieved. These improvements are attributed to solid solution strengthening, segregation strengthening, and grain refinement. The Zn-Cu alloys also demonstrated favorable degradation behavior, with a rate of 0.16 mm/year. This degradation is primarily driven by micro-galvanic corrosion between the CuZn5 phase and Zn matrix, along with refined grains and increased grain boundary density. This work demonstrates a viable strategy for fabricating Zn-based implants with enhanced structural integrity and mechanical performance via LPBF.