ZIF-67衍生Co/NC多孔碳材料的改性及其电催化水氧化性能

doi:10.11949/0438-1157.20191040

摘要/Abstract

摘要：

通过将前体ZIF-67高温热解并采用NaBH₄还原的方法制得表面富含氧空位的多孔碳复合材料(R-Co/NC-800)。利用X射线衍射(XRD)、场发射扫描电镜(FESEM)、高分辨透射电镜(HRTEM)、X射线光电子能谱仪(XPS)等手段对材料的物相、形貌、元素分布以及表面化学键结构等进行了表征；采用线性扫描伏安法(LSV)等方法研究了材料的电催化水氧化活性。结果表明制得的多孔碳复合材料(R-Co/NC-800)与未经NaBH₄还原处理的Co/NC-800样品对比，其表面氧空位浓度明显增加，形成新的催化活性位点，有效提升了电催化水氧化活性。在1.0 mol/L KOH溶液中，达到10 mA/cm²的电流密度，所需过电势仅为287 mV，同时表现出优异的电化学稳定性。

关键词: ZIF-67, 热解, 多孔碳, 复合材料, NaBH₄, 还原, 氧空位, 水氧化

Abstract:

A porous carbon composite (R-Co / NC-800) with oxygen vacancies on its surface was prepared by pyrolyzing the precursor ZIF-67 at high temperature and using NaBH₄ reduction. The structure, morphology, element distribution and valence state of the as-prepared samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), high resolution transmission electron microscope (HRTEM) and X-ray photoelectron spectroscope (XPS), respectively. The electrocatalytic performance of the as-prepared catalysts for oxygen evolution reaction (OER) was investigated by linear polarization curve (LSV) measurements. The R-Co/NC-800 with rich oxygen vacancies as electrocatalytic active sites and high specific surface area to expose amounts of unsaturated coordinate metal species after reconstruction the surface of Co/NC-800 via NaBH₄ solution, which exhibits higher catalytic activity for OER, delivering a current density of 10 mA/cm² at a low overpotential (287 mV) than that of Co/NC-800 (363 mV) in 1.0 mol/L KOH media, as well as outstanding long-term electrochemical durability.

Key words: ZIF-67, pyrolysis, porous carbon, composite, NaBH₄, reduction, oxygen vacancy, water oxidation

中图分类号:

TB 383

邹雷, 刘国强, 江苗苗, 杨则恒, 张卫新. ZIF-67衍生Co/NC多孔碳材料的改性及其电催化水氧化性能[J]. 化工学报, 2020, 71(6): 2821-2829.

Lei ZOU, Guoqiang LIU, Miaomiao JIANG, Zeheng YANG, Weixin ZHANG. Preparation and modification of ZIF-67 derived Co/NC porous carbon composite for electrocatalytic oxygen evolution reaction[J]. CIESC Journal, 2020, 71(6): 2821-2829.

图/表 6

图1 ZIF-67的XRD谱图(a)， Co/NC-700、Co/NC-800、Co/NC-900以及R-Co/NC-800的XRD图(b)， Co/NC-700、Co/NC-800、Co/NC-900以及R-Co/NC-800的拉曼光谱图(c)，Co/NC-800和R-Co/NC-800的氮气吸附-脱附等温线及其对应的孔径分布(d)

Fig.1 XRD patterns of ZIF-67(a), XRD patterns of Co/NC-700, Co/NC-800, Co/NC-900 and R-Co/NC-800(b), Raman spetra of Co/NC-700, Co/NC-800, Co/NC-900 and R-Co/NC-800(c), nitrogen adsorption-desorption isotherms and corresponding pore size of Co/NC-800 and R-Co/NC-800(d)

图2 ZIF-67(a)、Co/NC-800(b)的扫描电子显微镜图(插图为透射电子显微镜图)

Fig.2 SEM images of ZIF-67(a) and Co/NC-800(b) (inset: TEM images of ZIF-67 and Co/NC-800)

图3 R-Co/NC-800的扫描电子显微镜图(插图为透射电子显微图) (a)，高分辨电子显微镜图(b)、电子衍射图(c)以及元素分布图(d)

Fig.3 SEM image (inset: TEM image) (a), HRTEM image(b), electron diffraction image (c) and elemental mapping of R-Co/NC-800(d)

图4 Co/NC-800和R-Co/NC-800的XPS全谱图(a)，Co 2p XPS高分辨谱图(b)，N 1s高分辨谱图(c)， O 1s高分辨谱图(d)

Fig.4 XPS spectrum of Co/NC-800 and R-Co/NC-800(a), high-resolution XPS spectrum of Co 2p(b), N 1s (c) and O 1s (d) from Co/NC-800 and R-Co/NC-800

图5 ZIF-67、Co/NC-T(T = 700、800、900)以及R-Co/NC-800样品的电催化水氧化LSV极化曲线(a)，达到10 mA/cm2的过电势(b)， Tafel斜率(c)以及阻抗谱(d)

Fig.5 LSV curves(a), overpotential(b), Tafel plots (c) and EIS spectra (d) of ZIF-67, Co/NC-T (T = 700, 800, 900) and R-Co/NC-800

图6 Co/NC-800(a)及R-Co/NC-800(b)的CV极化曲线， Co/NC-800及R-Co/NC-800的双电层电容(c)， Co/NC-800和R-Co/NC-800的稳定性测试(d)

Fig. 6 CV curves of Co/NC-800 (a) and R-Co/NC-800(b); electrochemical double-layer capacitance of Co/NC-800 and R-Co/NC-800 (c); Stability test of Co/NC-800 and R-Co/NC-800(d)

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