Synthesis and electrocatalytic oxygen evolution performances of FeOOH-Ni(OH)2 composites
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摘要: 以碳纤维布(CFC)为基底,通过两步法(恒电流电沉积法、溶剂热法)成功制备了FeOOH-Ni(OH)2复合材料。与FeOOH和Ni(OH)2相比,该FeOOH-Ni(OH)2复合材料作为电催化剂时,电催化析氧反应(OER)活性显著提高。在1 mol/L KOH电解质溶液中,达到10 mA·cm−2电流密度时所需要的过电位仅为270 mV,Tafel斜率为78 mV/dec,电化学阻抗谱进一步揭示了电解过程中良好的动力学特性。FeOOH-Ni(OH)2复合材料在碱性介质中具有优异的稳定性,其在高电流密度下(50 mA·cm−2)的过电势经过连续24 h的测试之后几乎没有发生明显变化。FeOOH和Ni(OH)2之间的强电子相互作用和协同效应有效提高了电导性,促进了电荷转移;此外,这种核壳结构有效增强了电催化活性面积,进而增强了其电催化析氧性能。
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关键词:
- FeOOH-Ni(OH)2复合材料 /
- 核壳结构 /
- 协同效应 /
- 电催化 /
- 析氧反应
Abstract: FeOOH-Ni(OH)2 composites were successfully prepared on carbon fiber cloth (CFC) by electrochemical deposition and hydrothermal method. The electrocatalytic oxygen evolution activity of the FeOOH-Ni(OH)2 composite is significantly improved compared with FeOOH and Ni(OH)2. The FeOOH-Ni(OH)2 electrodes require an overpotential as low as 270 mV and the tafel slope to deliver 10 mA·cm−2 for oxygen evolution reaction (OER) in 1 mol/L KOH. The electrochemical impedance spectroscopy further reveals the favorable kinetic during electrolysis. Moreover, The FeOOH-Ni(OH)2 composite has excellent stability in the alkaline medium, and its overpotential remains stable during the 24 h test at high current density(50 mA·cm−2). The strong electron interaction and synergistic reaction between FeOOH and Ni(OH)2 are enhanced effectively. The conductivity promotes the charge transfer, and the core-shell structure effectively enhances the electrocatalytic activity area, and further enhances its oxygen evolution properties. -
图 2 FeOOH纳米片(a)、FeOOH-Ni(OH)2复合材料(b)和Ni(OH)2纳米片(j)的SEM图像以及FeOOH纳米片(c)和FeOOH-Ni(OH)2复合材料(d)的TEM图像、FeOOH-Ni(OH)2复合材料的HRTEM图像(e)、FeOOH-Ni(OH)2复合材料的元素分布图((f)~(i))
Figure 2. SEM images of FeOOH(a), FeOOH-Ni(OH)2 composites(b)and Ni(OH)2(j) and TEM images of FeOOH(c) and FeOOH-Ni(OH)2 composites(d), HRTEM image of FeOOH-Ni(OH)2 composites(e) and elemental mapping images of FeOOH-Ni(OH)2 composites((f)-(i))
图 5 FeOOH纳米片、Ni(OH)2纳米片及FeOOH-Ni(OH)2复合材料的极化曲线(a)、taifel斜率(b)、电化学阻抗谱(c)、双层电容曲线(d)及FeOOH-Ni(OH)2复合材料连续循环3000圈前后的极化曲线(e)、在碱性条件下电流密度50 mA·cm−2的计时-电压曲线(f)
Figure 5. Polarization curves(a), tafel plots(b), nyquist plots(c), the capacitive current densities plotted against scan rate(d) of the FeOOH-Ni(OH)2 composites, Ni(OH)2 sheets and FeOOH sheets and polarization curves of FeOOH-Ni(OH)2 composites before and after 3 000 CV cycles(e), chronopotentiometric curve of FeOOH-Ni(OH)2 composite at a constant current density of 50 mA·cm−2(f)
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