An iridium-free and low-ruthenium-content oxide (Cr0.6Ru0.4O2) derived from a metal-organic framework was prepared recently by Prof. CHEN Liang’s research group at the Institute of New Energy Technology, Ningbo Institute of Materials Technology and Engineering of Chinese Academy of Sciences.
This substance is quite active and low-cost, featuring excellent oxygen evolution reaction performance in acidic conditions with a record low overpotential of 178 mV at 10 mA cm-2. This study was published in Nature Communications.
Renewable energy sources will be of great significance in the near future. However, they are usually intermittent. It is necessary to explore the technology for converting the surplus power obtained from renewable energy sources to storable energy carriers such as hydrogen.
Members of Prof. CHEN's group have committed themselves to developing efficient electrocatalysts for the oxygen evolution reaction (OER). Recently Dr. LIN Yichao from this group prepared a new CrO2-RuO2 solid solution by using a Cr-based metal-organic framework (MOF) and determined the structure of the solid solution via PXRD characterizations and refinement.
Through the atomic-solution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), scientists observed that in this structure, Cr and Ru atoms are evenly distributed in the same nano-monocrystal.
They found that the solid solution exhibited an overpotential of merely 178 mV at the current density of 10 mA cm-2, and the overpotential only increased by 11 mV after 10,000 times of circulation, much more superior to the commercial RuO2.
"Such excellent performance is due to the shortening of Ru-O bond length and the valence of Ru atoms, which is slightly higher than +4, in the crystal structure caused by the strong electron withdrawing of Cr with a valence of +4," said Dr. LIN.
The reason for the superb performance was also verified theoretically. Through density functional theory (DFT) calculations, scientists found that the catalytic activity of Ru is increased because of the electron withdrawing of Cr with a valence of +4 in the lattice, thus reducing the reaction energy barrier.
Ru accounts for only 40% of the solid solution and the cost of this electrocatalyst was significantly reduced, making it ideal for commercialization and industrial application.
XU Linqi
Ningbo Institute of Materials Technology and Engineering
E-mail: xulinqi@nimte.ac.cn
The research team led by Prof. YU Shuhong at the University of Science of Technology of China (USTC) of Chinese Academy of Sciences has discovered a highly stable and active electrocatalyst for producing hydrogen from acidic water, even approaching the performance of noble-metal platinum that is an important step to realize the use of water as an energy source in our future society economically. This new electrocatalyst constructed by chemically combining two transitional metal dichalcogenides enables unexpected fast rate for making hydrogen and could be a very promising alternative to platinum.
Prof. MA Mingming's Group from University of Science & Technology of China of Chinese Academy of Sciences came up with a facile approach to synthesis cobalt-nanocrystal-assembled hollow nanoparticles (Co-HNP), which can serve as a highly active and stable electrocatalyst for hydrogen evolution reaction (HER) from neutral-pH water. This step is expected to promote the electrocatalytic hydrogen generation development.
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