Low‐Temperature Exsolution of Ni–Ru Bimetallic Nanoparticles from A‐Site Deficient Double Perovskites

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 18; no. 43; pp. e2107020 - n/a
• Main Authors: Guo, Jia, Cai, Rongsheng, Cali, Eleonora, Wilson, George E., Kerherve, Gwilherm, Haigh, Sarah J., Skinner, Stephen J.
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01-10-2022
• Subjects: bimetallic nanoparticles; Bimetals; Chemical reduction; Diameters; double perovskites; Electrocatalysts; Electrodes; Energy technology; Low temperature; low‐temperature exsolution; Nanoalloys; Nanoparticles; Nanotechnology; Ni–Ru alloys; Perovskites; Ruthenium; Temperature; low-temperature exsolution; bimetallic nanoparticles; Ni-Ru alloys; double perovskites
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.202107020

Exsolution of stable metallic nanoparticles for use as efficient electrocatalysts has been of increasing interest for a range of energy technologies. Typically, exsolved nanoparticles show higher thermal and coarsening stability compared to conventionally deposited catalysts. Here, A‐site deficient double perovskite oxides, La2‐xNiRuO6‐δ (x = 0.1 and 0.15), are designed and subjected to low‐temperature reduction leading to exsolution. The reduced double perovskite materials are shown to exsolve nanoparticles of 2–6 nm diameter during the reduction in the low‐temperature range of 350–450 °C. The nanoparticle sizes are found to increase after reduction at the higher temperature (450 °C), suggesting diffusion‐limited particle growth. Interestingly, both nickel and ruthenium are co‐exsolved during the reduction process. The formation of bimetallic nanoparticles at such low temperatures is rare. From the in situ impedance spectroscopy measurements of the double perovskite electrode layers, the onset of the exsolution process is found to be within the first few minutes of the reduction reaction. In addition, the area‐specific resistance of the electrode layers is found to decrease by 90% from 291 to 29 Ω cm2, suggesting encouraging prospects for these low‐temperature rapidly exsolved Ni/Ru alloy nanoparticles in a range of catalytic applications.
Nanoparticles exsolve from A‐site deficient double perovskites by reduction in wet 5%H2/Ar at a low‐temperature range from 350 to 450 °C. The socketed particles are found to be Ni–Ru alloys. In situ impedance spectroscopy reveals a fast exsolution process and significant electrochemical performance enhancement, suggesting the promising potential of the Ni–Ru decorated lanthanum nickel ruthenate double perovskite phase.