1成果简介
　　开发高效稳定的双功能催化剂对推进锌空气电池（ZABs）的大规模应用至关重要。本文，安徽工业大学Shilei Ding等研究人员在《Electrochimica Acta》期刊发表名为“Secondary Sulfidation-Engineered Co/N–Graphene Catalyst for Boosted ORR/OER Bifunctionality in Zinc–Air Batteries”的论文，研究通过两步硫化策略，合成了以氮掺杂石墨烯为载体的钴基硫化物复合催化剂（Co@NG-S2）。
　　首阶段硫化处理成功实现硫（S）与氮（N）的共掺杂，同时提升了石墨烯载体的导电性和活性。第二阶段硫化促进了钴基硫化物的均匀分布，并增强了其与石墨烯的界面耦合，从而显著提升了双功能催化性能。电化学表征显示，Co@NG-S2在红外电极上呈现出0.868 V的氧还原反应（ORR）起始电位和0.798 V的半波电位（E1/2）。对于氧析出反应（OER），Co@NG-S2在10 mA cm-2电流密度下仅表现出430 mV的低过电位，展现出卓越的ORR/OER双功能活性。此外，采用该催化剂组装的液态ZAB实现了110 mW cm-2的峰值功率密度，并展现出超过200小时的循环稳定性。本研究提出了一种合成高性能过渡金属硫化物-碳基催化剂的新策略，为未来应用展现出巨大潜力。
　　2图文导读 

　　图1. (a) Schematic diagram illustrating the synthesis process of the Co@NG-S2 catalyst. (b) Scanning electron microscopy (SEM) image of graphene. (c) SEM image of Co@NG. (d) SEM image of Co@NG-S1. (e-i) SEM image of Co@NG-S2 and its corresponding energy-dispersive X-ray spectroscopy (EDS) elemental mapping images. (j) Transmission electron microscopy (TEM) image of Co@NG-S2. (k, l) High-resolution transmission electron microscopy (HRTEM) images of Co@NG-S2.

　　图2. (a) Raman spectra of Co@NG, Co@NG-S1, and Co@NG-S2. (b) XRD patterns of Co@NG, Co@NG-S1, and Co@NG-S2. (c) XPS survey spectra, (d) High-resolution XPS spectra of Co 2p orbitals, (e) Deconvoluted high-resolution XPS spectra of Co 2p orbitals, (f) High-resolution XPS spectra of N 1s orbitals, (g) High-resolution XPS spectra of C 1s orbitals for Co@NG-S2, Co@NG-S1, and Co@NG. (h) High-resolution XPS spectra of S 2p orbitals for Co@NG-S2 and Co@NG-S1.

　　图3. Electrochemical performance of catalysts in 0.1 M KOH:(a) CV profiles of Co@NG-S2, Co@NG-S1, Co@NG, and Pt/C in O2-saturated and N2-saturated solutions, (b) ORR polarization curves at 1600 rpm, (c) Half-wave potentials and limiting current densities, (d) Tafel slopes derived from ORR polarization data. (e) OER polarization curves of Co@NG-S2, Co@NG-S1, Co@NG, and RuO2 catalysts. (f) Tafel slopes derived from OER polarization data. (g) Cdl of the samples. (h) ΔE values.

　　图4. Schematic Illustration of the Enhanced OER and ORR Mechanism by Secondary Sulfurization Optimized Catalysts.

　　图5. Rechargeable Zn-air battery assembled with Co@NG-S2 and Pt/C + RuO2: (a) Schematic diagram of the battery structure. (b) Open-circuit voltage. (c) Charge-discharge polarization curves. (d) Power density curves. (e) Partial view of constant-current charge-discharge cycling. (f) Photograph of an LED lit by the Co@NG-S2-based battery. (g) Long-term constant-current charge-discharge cycling profile.
　　3小结
　　本研究通过二次硫化法成功开发出一种由氮掺杂石墨烯负载的钴基硫化物组成的独立复合催化剂（Co@NG-S2）。该催化剂应用于锌空气电池（ZABs）时，对氧还原反应（ORR）和氧析出反应（OER）均展现出卓越的双功能催化活性。实验表征表明，该催化剂在0.1M KOH溶液中展现出高ORR活性，起始电位为0.868V，半波电位为0.798V（相对于还原氧化电极），表明其具有高效的四电子转移路径。在1.0M KOH溶液中的氧析出反应中，该催化剂表现卓越：于10mA cm⁻²电流密度下仅产生430 mV过电位，塔菲尔斜率达213.62mV dec⁻¹，彰显出快速反应动力学特性。此外，当集成于锌空气电池时，基于Co@NG-S2的空气阴极实现了高达110 mW cm-2的峰值功率密度，并展现出卓越的长期循环稳定性（超过200小时），超越了基准Pt/C+RuO2催化剂体系。本研究提出了一种新型高性能过渡金属硫化物-碳复合催化剂的工程化策略，为推进锌空气电池的实际应用提供了重要潜力。
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