Li Zhao, He Teng, Liu Lin, Chen Weidong, Zhang Miao, Wu Guotao, Chen Ping
Dalian National Laboratory for Clean Energy , Dalian Institute of Chemical Physics , Chinese Academy of Sciences , Dalian , 116023 , China . Email:
University of the Chinese Academy of Sciences , Beijing 100049 , China.
Chem Sci. 2017 Jan 1;8(1):781-788. doi: 10.1039/c6sc02456d. Epub 2016 Aug 30.
Development of non-noble metal catalysts with similar activity and stability to noble metals is of significant importance in the conversion and utilization of clean energy. The catalytic hydrolysis of ammonia borane (AB) to produce 3 equiv. of H, as an example of where noble metal catalysts significantly outperform their non-noble peers, serves as an excellent test site for the design and optimization of non-noble metal catalysts. Our kinetic isotopic effect measurements reveal, for the first time, that the kinetic key step of the hydrolysis is the activation of HO. Deducibly, a transition metal with an optimal electronic structure that bonds HO and -OH in intermediate strengths would favor the hydrolysis of AB. By employing a covalent triazine framework (CTF), a newly developed porous material capable of donating electrons through the lone pairs on N, the electron densities of nano-sized Co and Ni supported on CTF are markedly increased, as well as their catalytic activities. Specifically, Co/CTF exhibits a total turnover frequency of 42.3 mol mol min at room temperature, which is superior to all peer non-noble metal catalysts ever reported and even comparable to some noble metal catalysts.
开发具有与贵金属相似活性和稳定性的非贵金属催化剂在清洁能源的转化和利用中具有重要意义。氨硼烷（AB）催化水解生成3当量的H，在这方面贵金属催化剂明显优于非贵金属催化剂，这为非贵金属催化剂的设计和优化提供了一个很好的测试平台。我们的动力学同位素效应测量首次揭示，水解的动力学关键步骤是HO的活化。可以推断，具有最佳电子结构且能以中等强度键合HO和 -OH的过渡金属有利于AB的水解。通过使用共价三嗪框架（CTF），一种新开发的能够通过N上的孤对电子供电子的多孔材料，负载在CTF上的纳米Co和Ni的电子密度显著增加，其催化活性也随之提高。具体而言，Co/CTF在室温下的总周转频率为42.3 mol mol⁻¹ min⁻¹，优于以往报道的所有同类非贵金属催化剂，甚至可与一些贵金属催化剂相媲美。
