Enhancing the Catalytic Activity and Stability of Noble Metal Nanoparticles by the Strong Interaction of Magnetic Biochar Support

In this study, the catalytic activity and stability of Pd nanoparticles during the reduction of 4-nitrophenol (4-NP) were significantly enhanced by the interaction of Fe3O4/biochar support prepared by pyrolysis of fir sawdust. Compared with the commercial Pd/C with 5% of Pd content, the as-synthesized Pd@Fe3O4/biochar with only 1.58% of Pd content exhibited twice higher catalytic performance toward the 4-NP reduction. The significant enhancement of catalytic activity was ascribed to the interaction between Fe and Pd NPs which lowers the binding energy of Pd on surface of Pd@Fe3O4/biochar, resulting the fast desorption of the intermediate species during the reaction. Furthermore, the carbon skeleton expedites the electron transfer and facilitates the formation of active hydrogen and deprotonation of 4-NP which are key steps of reduction of 4-NP. The abundant oxygen containing groups in biochar may act as pinchers to tightly fix the Pd NPs and improve the stability of Pd@Fe3O4/biochar.