Selectively coupled small Pd nanoparticles on sp2-hybridized domain of graphene-based aerogel with enhanced catalytic activity and stability

Abstract

The precisely coupling of metal nanoparticles with support domain are crucial to enhance the catalytic activity and stability of supported metal nanoparticle catalysts (MNPs). Here we selectively anchor Pd nanoparticles to the sp2 domain in graphene-based aerogel constructed with base-washed graphene oxide (BGO) by removing oxidative debris (OD). The effects of OD on the size and chemical composition of Pd nanoparticles in aerogels are initially unveiled. The removal of OD nanoparticles prompt selective coupling of Pd nanoparticles to the exposed sp2-hybridized domain on BGO nanosheets, and then prevent it from agglomeration. As a result, the Pd nanoparticle size of self-assembled Pd/BGA is 4.67 times smaller than that of traditional Pd/graphene oxide aerogel (Pd/GA). The optimal catalytic activity of Pd/BGA for the model catalytic reduction of 4-nitrophenol is 15 times higher than that of Pd/GA. Pd/BGA could maintain its superior catalytic activity and achieves 98.72% conversion in the fifth cycle. The superior catalytic performance could be ascribed to the small Pd nanoparticles and high percentage of Pd(0) in Pd/BGA, and the enhanced electronic conductivity of Pd/BGA. These integrated merits of Pd/BGA as heterogeneous catalysts are attributed to selectively anchor Pd nanoparticles on sp2-hybridized domain of graphene-based aerogel, and strongly coupled interaction of MNPs with support. The structure-regulated BGO nanosheets could serve as versatile building blocks for fabricating MNPs/graphene aerogels with superior performance for catalytic transformation of water pollutants.