Wang Teng, Jin Rumei, Wu Yong, Zheng Jie, Li Xingguo
Beijing National Laboratory for Molecular Sciences (BNLMS), College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
Nanoscale Horiz. 2018 Mar 1;3(2):218-225. doi: 10.1039/c7nh00193b. Epub 2018 Jan 12.
A highly efficient catalyst for the hydrogen evolution reaction (HER) composed of Ni nanoparticles encapsulated in thin layers of N-doped carbon (Ni@NC) can be obtained by NH induced fragmentation of a Ni based MOF at mild temperature (450 °C). A mechanistic study shows that the high chemical reactivity of NH causes ammonolysis of the ligands and allows ligand removal well below their carbonization temperature. In conventional thermal decomposition in Ar, metal-ligand bond dissociation and ligand carbonization occurs in the same temperature region, resulting in a catalyst with high carbon content and much poorer HER performance. We further improve the HER performance by combining the NH induced fragmentation and destabilization of the Ni-MOF structure by low levels of Co substitution, which results in smaller, more uniform catalyst particles. Using the noble metal free HER catalyst, an overall solar-to-hydrogen efficiency of 7.9% is achieved in an electrolyzer driven by a commercial polycrystalline solar cell with an efficiency of 12.9%.
一种用于析氢反应（HER）的高效催化剂，由包裹在薄层氮掺杂碳（Ni@NC）中的镍纳米颗粒组成，可通过在温和温度（450°C）下NH诱导镍基金属有机框架（MOF）的碎片化来获得。机理研究表明，NH的高化学反应性导致配体氨解，并允许在远低于其碳化温度的情况下去除配体。在Ar中的传统热分解中，金属-配体键解离和配体碳化发生在相同的温度区域，导致催化剂碳含量高且HER性能差得多。我们通过将NH诱导的碎片化与低水平Co取代对Ni-MOF结构的去稳定化相结合，进一步提高了HER性能，这导致催化剂颗粒更小、更均匀。使用无贵金属的HER催化剂，在由效率为12.9%的商用多晶太阳能电池驱动的电解槽中，实现了7.9%的整体太阳能到氢能效率。
