When serving as a “precatalyst”, metal-organic frameworks (MOF) usually incur uncontrollable framework collapse in electrocatalysis. Herein, we report an anticollapse MOF-supported single-atom Cu precatalyst for electrocatalytic nitrate-to-ammonia reduction reaction (NARR), which can be applied in the rechargeable ammonia energy storage (RAES) technology. In situ X-ray absorption spectroscopy (XAS) revealed the association of the formation of real catalytic sites with the in situ clustering of single-atom Cu during NARR. Notably, the noncollapse MOF can afford the confined space to prevent the excessive aggregation of Cu atoms, leading to uniform ultrasmall nanoclusters (ca. 4 nm). Moreover, it achieves a maximal Faradaic efficiency toward NH3 of 85.5%, a formation rate of NH3 of 66 μmol h–1 cm–2, and a specific activity of 53.43 mgNH3 h–1 mgCu –1 in 5 mM NO3 – solution. The specific activity is found to be at least 3.3 times higher than that of other reported Cu-based catalysts. Density function theory (DFT) calculation further confirms the size effect and the host–guest interaction in facilitating the NO3 – activation and the reaction energy decrease. Besides, it also exhibits a high selectivity of ammonia-to-nitrate of 93.3%, displaying great potential in RAES technology.

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This work developed three high-nuclearity {Co14} clusters of C1–C3 with inner [Co8] backbone fixed by six ambient CoCl2 species. The catalyst C1 exhibited highly regio- and stereoselective hydrosilylation of alkynes with primary and secondary silane to produce α-vinylsilanes. More importantly, C1 shows high regioselectivity for electronically unbiased alkyl alkynes, and the α-selectivity of some alkyl alkynes has not been achieved in previous reports. Leaching tests and reusability proved that the reaction is a heterogeneous process.