Fan Weiwei, Wang Baoming, Gao Rui, Dimitrakopoulos Georgios, Wang Jiayue, Xiao Xianghui, Ma Lu, Wu Kai, Yildiz Bilge, Li Ju
Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
J Am Chem Soc. 2022 May 4;144(17):7657-7666. doi: 10.1021/jacs.1c12970. Epub 2022 Apr 26.
Nanoparticles decorated electrodes (NDEs) are useful in fuel cells, electrolyzers, water treatment, and chemical synthesis. Here, we show that by rapidly bringing a mixed ionic-electronic conductor outside its electrochemical stability window, one can achieve uniform dispersion of metallic nanoparticles inside its bulk and at the surface and improve its electrocatalytic performance when back under normal functional conditions. Surprisingly, this can happen under anodic as well as cathodic current/voltage shocks in an ABO perovskite oxide, LaCaTiFeNiO (LCTFN), across a wide range of H/O gas environments at 800 °C. One possible mechanism for bulk Fe/Ni precipitation under anodic shock condition is the incomplete oxygen oxidation (O → O, 0 < α < 2), migration and escape of oxygen to interfaces, and "whiplash" transition-metal reduction due to low electronic conductivity. We show that both cathodic and anodic shocks can produce NDEs to enhance electrocatalytic performance, potentially improving the flexibility of this approach in practical devices.
纳米颗粒修饰电极（NDEs）在燃料电池、电解槽、水处理和化学合成中很有用。在此，我们表明，通过迅速将混合离子电子导体带离其电化学稳定窗口，人们可以在其内部和表面实现金属纳米颗粒的均匀分散，并在回到正常功能条件下时提高其电催化性能。令人惊讶的是，在800℃的各种H/O气体环境中，在ABO钙钛矿氧化物LaCaTiFeNiO（LCTFN）中，阳极和阴极电流/电压冲击下都会发生这种情况。阳极冲击条件下本体Fe/Ni析出的一种可能机制是氧的不完全氧化（O→O，0＜α＜2）、氧向界面的迁移和逸出，以及由于低电子电导率导致的“鞭打”过渡金属还原。我们表明，阴极和阳极冲击都可以产生NDEs以增强电催化性能，这可能会提高这种方法在实际装置中的灵活性。
