Hexavalent Ru Catalyst with Both Lattice Oxygen and Metal Ion Mechanisms Coactive for Water Oxidation
Yanzhuo Li, Jianfa Zhao, Shengjie Zhang, Yalei Fan, Chang‐Yang Kuo, Yu‐Chieh Ku, Ting‐Shan Chan, Cheng‐Wei Kao, Yucheng Huang, Chien‐Te Chen, Shu‐Chih Haw, Changqing Jin, Hongbin Zhao, Daixin Ye, Chao Jing, Zhiwei Hu, Linjuan Zhang
Abstract
High Resolution Image Download MS PowerPoint Slide Green hydrogen from water requires the development of efficient and low-cost catalysts for anodic oxygen evolution reaction (OER), which is the main obstacle for electrochemical water splitting. Herein, we focus on an OER catalyst (Pb 2 CoRuO 7 ) featuring Ru 6+, which exhibits an ultralow overpotential of 176 mV at 10 mA cm –2 and a Tafel slope of 30.52 mV dec –1 vs 340 mV at 10 mA cm –2 and a Tafel slope of 111.54 mV dec –1 for RuO 2 in 1.0 M KOH solution. In situ X-ray absorption experiments demonstrated the gradual conversion of Ru 5+ ions into high-valence Ru 6+, while a portion of Co 3+ ions transformed into Co 4+ during the OER process. Density functional theory calculations revealed that the ultrahigh OER activity of Pb 2 CoRuO 7 was contributed by both metal-site adsorbate evolution (MAE) at the Co site and the lattice-oxygen-vacancy-site (LOV) mechanism involving lattice oxygen located between Ru 6+ and Co. Our work presents a new and unusual OER catalyst where both the MAE and LOV mechanisms cooperatively facilitate catalytic activity.