Sarac Baran, Ivanov Yurii P, Micusik Matej, Karazehir Tolga, Putz Barbara, Dancette Sylvain, Omastova Maria, Greer A Lindsay, Sarac A Sezai, Eckert Jürgen
Erich Schmid Institute of Materials Science, Austrian Academy of Sciences, 8700 Leoben, Austria.
Department of Materials Science & Metallurgy, University of Cambridge, Cambridge CB3 0FS, U.K.
ACS Appl Mater Interfaces. 2021 Sep 15;13(36):42613-42623. doi: 10.1021/acsami.1c08560. Epub 2021 Sep 7.
Contrary to the electrochemical energy storage in Pd nanofilms challenged by diffusion limitations, extensive metal-hydrogen interactions in Pd-based metallic glasses result from their grain-free structure and presence of free volume. This contribution investigates the kinetics of hydrogen-metal interactions in gold-containing Pd-based metallic glass (MG) and crystalline Pd nanofilms for two different pore architectures and nonporous substrates. Fully amorphous MGs obtained by physical vapor deposition (PVD) co-sputtering are electrochemically hydrogenated by chronoamperometry. High-resolution (scanning) transmission electron microscopy and corresponding energy-dispersive X-ray analysis after hydrogenation corroborate the existence of several nanometer-sized crystals homogeneously dispersed throughout the matrix. These nanocrystals are induced by PdH formation, which was confirmed by depth-resolved X-ray photoelectron spectroscopy, indicating an oxide-free inner layer of the nanofilm. With a larger pore diameter and spacing in the substrate (Pore40), the MG attains a frequency-independent impedance at low frequencies (∼500 Hz) with very high Bode magnitude stability accounting for enhanced ionic diffusion. On the contrary, on a substrate with a smaller pore diameter and spacing (Pore25), the MG shows a larger low-frequency (0.1 Hz) capacitance, linked to enhanced ionic transfer in the near-DC region. Hence, the nanoporosity of amorphous and crystalline metallic materials can be systematically adjusted depending on AC- and DC-type applications.
与受扩散限制挑战的钯纳米薄膜中的电化学能量存储相反，钯基金属玻璃中广泛的金属 - 氢相互作用源于其无晶粒结构和自由体积的存在。本研究针对两种不同的孔结构和无孔基底，研究了含金银钯基金属玻璃（MG）和结晶钯纳米薄膜中氢 - 金属相互作用的动力学。通过物理气相沉积（PVD）共溅射获得的完全非晶态MG通过计时电流法进行电化学氢化。氢化后的高分辨率（扫描）透射电子显微镜和相应的能量色散X射线分析证实了在整个基体中均匀分散着几个纳米尺寸的晶体。这些纳米晶体是由PdH形成诱导的，深度分辨X射线光电子能谱证实了这一点，表明纳米薄膜的内层无氧化物。对于基底中孔径和间距较大的情况（Pore40），MG在低频（约500Hz）下获得了与频率无关的阻抗，具有非常高的波特幅值稳定性，这归因于离子扩散增强。相反，在孔径和间距较小的基底（Pore25）上，MG显示出更大的低频（0.1Hz）电容，这与近直流区域中增强的离子转移有关。因此，非晶态和结晶态金属材料的纳米孔隙率可以根据交流和直流类型的应用进行系统调整。
