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 NH₃ induced fragmentation of a Ni based MOF at mild temperature (450 °C). A mechanistic study shows that the high chemical reactivity of NH₃ 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 NH₃ 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%.

中文翻译：

---

化学诱导的MOF裂解，用于高效Ni基析氢催化剂†

通过在温和的温度（450°C）下通过NH ₃诱导的Ni基MOF碎裂，可以获得由封装在N掺杂碳（Ni @ NC）薄层中的Ni纳米颗粒组成的高效氢气分解反应（HER）的催化剂。）。机理研究表明，NH ₃的高化学反应性会引起配体的氨解，并使配体的去除远低于其碳化温度。在Ar的常规热分解中，金属-配体键解离和配体碳化在相同的温度范围内发生，导致催化剂的碳含量高而HER性能差得多。我们通过结合NH ₃进一步提高HER性能钴的低含量引起Ni-MOF结构的断裂和失稳，从而导致催化剂颗粒更小，更均匀。使用不含贵金属的HER催化剂，在由市售多晶太阳能电池驱动的电解槽中，太阳能对氢的总效率为7.9％，效率为12.9％。