CuCo嵌入氮掺杂碳作为高效可充电锌-乙醇/空气电池的双功能催化剂

1成果简介

传统锌空气电池（ZAB）中的氧析出反应（OER）涉及复杂的多电子转移过程，导致反应动力学缓慢、充电电压高且能量效率低。为克服这些局限，提出了一种锌乙醇/空气电池（ZEAB）体系，该体系通过战略性地用具有较低热力学电位的乙醇氧化反应（EOR）替代氧析出反应。本文，湖南师范大学 杨亚辉教授、Chao Xie等在《ACS Appl. Mater. Interfaces》期刊发表名为“CuCo-Embedded Nitrogen-Doped Carbon as a Bifunctional Catalyst for Efficient Rechargeable Zinc–Ethanol/Air Batteries”的论文，研究基于Cu/Co/Cd共配位金属有机前驱体，合成了嵌入氮掺杂碳的双金属催化剂CuCo-20%-1，该催化剂在乙醇氧化反应（EOR）和氧还原反应（ORR）中均展现出优异性能。

系列表征与原位拉曼光谱分析证实：双金属CuCo物种经原位电化学过程形成高密度M–Nx位点及Cu掺杂的CoOOH，分别作为氧还原反应（ORR）与乙醇氧化反应（EOR）的催化活性位点。结合密度泛函理论计算，阐明了Cu掺杂CoOOH在EOR中的催化反应路径与增强机制。ZEAB系统展现出卓越的运行指标，实现63.4%的能量效率，较传统ZAB电池降低32.7%的能耗。这种从氧还原反应（OER）转向氧还原反应（EOR）的战略性替代方案，不仅突破了基础动力学限制，更为推动新一代金属空气电池技术的实际应用奠定了可行框架。

2图文导读

图1. (a) Schematic illustration of the preparation of CuCo-20%-1. (b and c) SEM images of CuCo-20%-1 at different scales. (d and e) High-resolution TEM images, (f) corresponding FFT pattern, and (g) STEM image of CuCo-20%-1.

图2. (a, b) XRD patterns, (c) N2 adsorption–desorption isotherms, and (d) the corresponding pore size distribution of samples. (e) Cu 2p and (f) Co 2p XPS spectra of CuCo-20%-0.5, CuCo-20%-1, CuCo-20%-2, Cu-20%, and Co-20% samples.

图3. (a) LSV curves, (b) Tafel plots, and (c) H2O2 yield and electron transfer number of the samples and Pt/C. (d) LSV curves in an O2-saturated 0.1 M KOH solution at various rotation rates and (e) the corresponding K–L plots at different potentials of CuCo-20%-1. (f)i–ttests at 0.6 V (vs RHE) of samples and Pt/C for ORR.

图4. (a) LSV curves of CuCo-20%-1 for EOR and OER in 1.0 M KOH with or without 1.0 M ethanol. (b) LSV curves. (c) Comparison of the required EOR potentials for CuCo-20%-0.5, CuCo-20%-1, CuCo-20%-2, Cu-20%, and Co-20% at various current densities. (d) Tafel plots, (e) Nyquist plots, and (f) Bode plots under different potentials of samples for EOR. The blue area represents the low-frequency (θ1) region, and the yellow area represents the high-frequency (θ2) region.

图5. (a) Schematic illustration of the ZEAB. Gray balls = C; white balls = H; and red balls = O. (b) Galvanostatic charging–discharging cycling curves at 5 mA cm–2. (c) 1H NMR measurements of the charging products after 12 h.

图6. (a) In situ Raman spectroscopy of CuCo-20%-1 at various applied potentials for the EOR and the OER and DFT calculations. (b) Charge density difference between the Cu-CoOOH and CoOOH sites. Charge accumulation and depletion are shown in cyan and yellow, respectively. (c) Scheme of the intermediates and major products involved in the EOR. (d) Reaction free energy diagram of the C2 pathways on the CoOOH and Cu-CoOOH sites. Brown ball = C; white ball = H; pink ball = O; orange ball = Cu; and blue ball = Co.

3小结

综上所述，作者合成了具有优异氧还原反应（ORR）和氧析出反应（EOR）电催化性能的CuCo嵌入氮掺杂碳双功能催化剂。结合原位拉曼光谱的一系列表征证实，高密度的M–Nx物种和电化学重构的Cu掺杂CoOOH分别是ORR和EOR的真实活性位点。进一步的密度泛函理论计算揭示了铜掺杂通过电子调谐机制增强CoOOH上氧还原效率的机理。该催化剂成功应用于ZEAB电池，与传统ZAB相比，充放电电压差缩小超过330 mV，能量效率提升达32.7%。本研究提出了一种制备高性能双功能催化剂的简明有效策略，该催化剂适用于新型金属空气/有机电池的阴极。

文献：

https://doi.org/10.1021/acsami.5c14058

来源：材料分析与应用