Stabilizing the OOH intermediate via pre-adsorbed surface oxygen of a single Ru atom-bimetallic alloy for ultralow overpotential oxygen generation

• Published in: Energy & environmental science Vol. 13; no. 12; pp. 5152 - 5164
• Main Authors: Lee, Jinsun, Kumar, Ashwani, Yang, Taehun, Liu, Xinghui, Jadhav, Amol R, Park, G. Hwan, Hwang, Yosep, Yu, Jianmin, Nguyen, Chau TK, Liu, Yang, Ajmal, Sara, Kim, Min Gyu, Lee, Hyoyoung
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 01.12.2020
• Subjects: Absorption spectroscopy; Alkaline water; Bimetals; Catalysts; Cobalt; Cobalt base alloys; Density functional theory; Durability; Electrocatalysts; Oxygen; Oxygen evolution reactions; Transmission electron microscopy; X ray absorption; X-ray absorption spectroscopy
• ISSN: 1754-5692; 1754-5706
• DOI: 10.1039/D0EE03183F

Designing efficient oxygen evolution reaction (OER) electrocatalysts based on single-atom catalysts is a highly promising option for cost-effective alkaline water electrolyzers. However, the instability of the OOH* intermediate and high energy barrier for the rate-determining step (RDS) (O* to OOH*) on the pure bimetallic-alloy represent serious challenges. Here, we report atomically dispersed Ru single-atoms on a cobalt–iron bimetallic-alloy encapsulated by graphitic carbon (Ru SA CoFe 2 /G) as an efficient and durable electrocatalyst for the alkaline OER. In-depth X-ray absorption spectroscopy (XAS) and aberration-corrected transmission electron microscopy (AC-TEM) along with theoretical calculations were employed to validate the isolated Ru sites in the surface-oxygen rich alloy. Ru SA CoFe 2 /G displays exceptional intrinsic activity, achieving a record low overpotential of only 180 mV at 10 mA cm −2 with superior durability in alkali media. Density functional theory (DFT) simulations revealed that the isolated Ru sites with pre-adsorbed surface oxygen species on a bimetallic-alloy efficiently stabilize the OOH* intermediate and significantly reduce the energy barrier for the RDS, boosting the intrinsic OER activity. Our integrated alkaline electrolyzer demands a low cell voltage of 1.48 V at 10 mA cm −2 , suggesting that it has potential for use in practical applications.