The graphene supported Cu₂O nanoparticles were prepared via a two-step liquid-phase method and exhibited high catalytic activity and stability for the Ullmann coupling of aryl halides with N–H containing compounds under mild and ligand-free conditions. The yield of C–N cross-coupling of imidazole with iodobenzene reached up to 97% with 0.5 mol% Cu (vs. reported 5–10 mol%). The high activity and stability of Cu₂O/graphene are probably due to the unique structure of graphene, which can make Cu₂O nanoparticles highly dispersed and prevent them from aggregation and oxidation.

中文翻译：

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铜2O /石墨烯是一种高效且无配体的异构催化剂，用于将含NH的化合物与芳基卤化物进行乌尔曼偶联

石墨烯负载的Cu ₂ O纳米颗粒是通过两步液相方法制备的，在温和且无配体的条件下，芳基卤化物与含N–H的化合物的Ullmann偶联反应具有很高的催化活性和稳定性。含0.5 mol％的铜时，咪唑与碘苯的C–N交叉偶联收率高达97％（相对于报道的5-10 mol％）。Cu ₂ O /石墨烯的高活性和稳定性可能归因于石墨烯的独特结构，可以使Cu ₂ O纳米颗粒高度分散并防止其聚集和氧化。