Ruthenium-based catalyst is one of the most active catalysts for oxygen evolution reaction (OER) in acid media. However, the strong bonding between the Ru sites and oxygen intermediates leads to high overpotential to trigger the OER process. Hence, pyrochlore rare-earth ruthenate (RE2-Ru2O7) structures with a series of rare-earth elements (Nd, Sm, Gd, Er, and Yb) were constructed to tune the electronic structure of the Ru sites. Surface structure analysis indicated that the increase of the radius of the rare-earth cations resulted in higher content of defective oxygen (the percentage of the defective oxygen increased from 29.5% to 49.7%) in the RE2Ru2O7 structure due to the weakened hybridization of the Ru-O bond. This reduced the valence states of the Ru sites and enlarged the gap between the 4d band center and the Fermi level (EF) of Ru, resulting in the weakened adsorption of oxygen intermediates and the improved OER performance in acid media. Among the as-prepared ruthenium pyrochlores, Nd2Ru2O7 displayed the lowest OER onset overpotential (210 mV) and Tafel slope (58.48 mV dec−1), as well as 30 times higher intrinsic activity and much higher durability than the state-of-art RuO2 catalyst.
钌(Ru)基催化剂是酸性介质中析氧反应(OER)最为活泼的催 化剂之一. 然而, Ru活性位点与含氧中间产物之间的强键合导致析 氧反应过电势较高. 本文, 利用一系列稀土元素(Nd、Sm、Gd、Er 和Yb)构建了烧绿石型稀土钌酸盐(RE2Ru2O7)结构来调整Ru位点 的电子结构. 表面结构分析表明, 由于Ru–O键杂化减弱, 随着稀土 离子半径的增大, RE2Ru2O7结构中缺陷氧含量增加(缺陷氧的比例 从29.5%增加到49.7%). 降低了的Ru的价态, 扩大了Ru的4d能带中 心与费米能级(EF)之间的间隙, 从而削弱了对氧中间体的吸附, 提 高了酸性介质中的OER性能. 在所制备的钌烧绿石中, Nd2Ru2O7表 现出最低的O E R 起始过电势(2 1 0 m V) 和T a f e l 斜率 (58.48 mV dec−1), 并且比最先进的RuO2催化剂具有高30倍的固有 活性和更好的耐久性.
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This work was supported by the National Key Research and Development Project (2018YFB1502401), the National Natural Science Foundation of China (21771018 and 21875004), the Royal Society and Newton Fund through Newton Advanced Fellowship award (NAFR1191294), the Program for Changjiang Scholars and Innovation Research Team in the University (IRT1205), the Fundamental Research Funds for the Central Universities, and the long-term subsidy mechanism from the Ministry of Finance and the Ministry of Education of China.
Liu H, Wang Z, Kuang Y and Sun X conceived the research; Liu H, Wang Z and Wang S designed and carried out the experiments; Zhao X, Duan X, Liu H and Wang Z did the DFT calculations; Liu H, Wang Z and Li M draw the figures; all the authors analyzed the data; Liu H, Wang Z, Kuang Y and Sun X wrote the paper.
Conflict of interest
The authors declare no conflict of interest.
Hai Liu is a PhD student at Beijing University of Chemical Technology (BUCT) under the supervision of Prof. Xiaoming Sun. His current research focuses on electrocatalytic water oxidation in acidic media.
Zhaolei Wang is a PhD student at BUCT under the supervision of Prof. Xiaoming Sun. His current research focuses on electrocatalytic water oxidation.
Yun Kuang obtained his BE and PhD degrees from BUCT in 2010 and 2015, respectively. He then joined the faculty of BUCT. He is now an associate professor in chemistry at the College of Chemistry, BUCT and a visiting associate professor in the Department of Chemistry, Stanford University. His current research interest mainly focuses on the synthesis, structure regulation and assembly of transitional metal-based nanostructures under control, as well as their application in catalysis and energy-related area.
Xiaoming Sun received his BSc degree and PhD degree from the Department of Chemistry, Tsinghua University in 2000 and 2005, respectively. After postdoctoral work at Stanford University, he joined the State Key Laboratory of Chemical Resource Engineering, BUCT in 2008. His main research interests focus on parathion and assembly of inorganic nanostructures, synthesis and separation of carbon nanomaterials and their composites, and structure control and opto-/eletro-property investigations of oxide nanoarrays.
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Liu, H., Wang, Z., Li, M. et al. Rare-earth-regulated Ru-O interaction within the pyrochlore ruthenate for electrocatalytic oxygen evolution in acidic media. Sci. China Mater. (2021). https://doi.org/10.1007/s40843-020-1571-y
- oxygen evolution
- ruthenium pyrochlore
- rare earth elements
- defective oxygen
- d band center
- valence state