Nitrogen-rich covalent organic frameworks (COFs) with a high content of nitrogen and an inherent porous skeleton are considered as a remarkable support for encapsulating active metal nanoparticles (MNPs). Herein, a cost-effective and nitrogen-rich COF (PC-COF) synthesized from piperazine and cyanuric chloride was used as a carrier for encapsulating Rh NPs via a metal–nitrogen (M–N) coordination reduction strategy. Numerous precisely tailored N atoms within the PC-COF facilitate the construction of Rh–N complexes between Rh ions and N atoms, which can be in situ reduced to produce ultrafine Rh NPs confined in the pores of the PC-COF. The optimized Rh/PC-COF catalyst shows uniform dispersibility and a fairly narrow distribution (1.4–2.6 nm) of Rh NPs, giving an ultrahigh catalytic activity for the methanolysis of ammonia borane (AB) with a total turnover frequency (TOF) of 505 min⁻¹ at 298 K. The excellent catalytic performances can be ascribed to the ultrafine particle size, electronic-rich Rh NPs, and the synergistic effect of the Rh NPs and PC-COF. The M–N coordination reduction strategy for encapsulating ultrafine MNPs into the pores of COFs opens a valuable pathway for developing metal nanocatalysts with high catalytic performance and excellent stability.

中文翻译：

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富氮共价有机骨架限制的超细Rh纳米粒子用于氨硼烷的甲醇分解

具有高氮含量和固有多孔骨架的富氮共价有机骨架（COF）被认为是封装活性金属纳米粒子（MNP）的出色载体。在本文中，由哌嗪和氰尿酰氯合成的具有成本效益的富氮COF（PC-COF）被用作通过金属-氮（M-N）配位还原策略封装Rh NP的载体。PC-COF中大量精确定制的N原子有助于在Rh离子和N原子之间构建Rh-N络合物，该络合物可以原位形成还原后可产生限制在PC-COF孔中的超细Rh NP。优化的Rh / PC-COF催化剂显示出均匀的分散性和相当窄的Rh NPs分布（1.4-2.6 nm），为氨硼烷（AB）的甲醇分解提供了超高的催化活性，总周转频率（TOF）为505 min ^-1在298 K时。出色的催化性能可归因于超细粒径，富电子的Rh NPs以及Rh NPs和PC-COF的协同作用。将超细MNP封装到COF孔中的M–N配位还原策略为开发具有高催化性能和出色稳定性的金属纳米催化剂开辟了一条有价值的途径。