Bifunctional Nanocatalyst Based on Three-Dimensional Carbon Nanotube–Graphene Hydrogel Supported Pd Nanoparticles: One-Pot Synthesis and Its Catalytic Properties

We reported the development of a new type of bifunctional nanocatalyst based on three-dimensional (3D) macroscopic carbon nanotube (CNT)–graphene hydrogel (GH) supported Pd nanoparticles (i.e., Pd–CNT–GH) and explored its practical application in catalytic reduction of <i>p</i>-nitrophenol to <i>p</i>-aminophenol. The 3D Pd–CNT–GH was synthesized by a facile one-pot self-assembled approach through hydrothermal treatment of a mixed aqueous precursor solution of PdCl₄^2–, CNT, and graphene oxide (GO). Under the appropriate condition, the spontaneous redox reaction between precursor PdCl₄^2– and CNT–GO as well as the self-assembly of macroscopic CNT–GH occurs simultaneously, leading to the formation of 3D Pd–CNT–GH. Because of the unique structural and functional properties of different components in the nanocatalyst and the synergistic effect between them, the as-prepared Pd–CNT–GH exhibits superior catalytic performance toward the reduction of <i>p</i>-nitrophenol to <i>p</i>-aminophenol, with 100% conversion within 30 s, even when the content of Pd in it is as low as 2.98 wt %. Moreover, after 20 successive cycles of reactions, the reaction time still keeps within 46 s. Therefore, the rational design of 3D macroscopic graphene-based nanohybrid material supported highly catalytically active nanoparticles, combined with the facile one-pot self-assembled strategy, provide a universal platform to fabricate desired 3D multifunctional nanomaterials that can be used in a broad range of catalysis, environmental protection, energy storage and conversation, drug delivery, chemical and biological sensing, and so forth