Fang Shi, Zhu Xiaorong, Liu Xiaokang, Gu Jian, Liu Wei, Wang Danhao, Zhang Wei, Lin Yue, Lu Junling, Wei Shiqiang, Li Yafei, Yao Tao
National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230029, P.R. China.
Jiangsu Collaborative Innovation Centre of Biomedical Functional Materials, Jiangsu Key Laboratory of New Power Batteries, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing, 210023, P.R. China.
Nat Commun. 2020 Feb 25;11(1):1029. doi: 10.1038/s41467-020-14848-2.
Single-atom catalysts offering intriguing activity and selectivity are subject of intense investigation. Understanding the nature of single-atom active site and its dynamics under working state are crucial to improving their catalytic performances. Here, we identify at atomic level a general evolution of single atom into a near-free state under electrocatalytic hydrogen evolution condition, via operando synchrotron X-ray absorption spectroscopy. We uncover that the single Pt atom tends to dynamically release from the nitrogen-carbon substrate, with the geometric structure less coordinated to support and electronic property closer to zero valence, during the reaction. Theoretical simulations support that the Pt sites with weakened Pt-support interaction and more 5d density are the real active centers. The single-atom Pt catalyst exhibits very high hydrogen evolution activity with only 19 mV overpotential in 0.5 M HSO and 46 mV in 1.0 M NaOH at 10 mA cm, and long-term durability in wide-pH electrolytes.
具有引人关注的活性和选择性的单原子催化剂是深入研究的对象。了解单原子活性位点的本质及其在工作状态下的动态变化对于提高其催化性能至关重要。在此，我们通过原位同步辐射X射线吸收光谱，在原子水平上确定了在电催化析氢条件下单原子向近自由状态的一般演化过程。我们发现，在反应过程中，单个铂原子倾向于从氮碳基底动态释放，其几何结构的配位作用减弱以提供支撑，电子性质更接近零价。理论模拟表明，铂-载体相互作用减弱且5d密度更高的铂位点是真正的活性中心。单原子铂催化剂在10 mA cm² 电流密度下，在0.5 M H₂SO₄ 中过电位仅为19 mV，在1.0 M NaOH中为46 mV，表现出非常高的析氢活性，并且在宽pH值电解质中具有长期耐久性。
