Synthesis and catalytic performance of h-Au/PDA@PDA@Fe3O4 hollow spheres for the 4-NP reduction

The research and progress of noble metal catalysts possessing good stability and extended service life holds significant importance in enhancing catalytic efficiency, reducing enterprise costs, and fostering sustainable social development. Here, a hollow magnetic h-Au/PDA@PDA@Fe3O4 catalyst with a double-layer PDA structure was prepared to optimize the stability of gold nanoparticles (NPs) using for the 4-nitrophenol (4-NP) reduction. The research indicates that, despite the initial activity of h-Au/PDA@PDA@Fe3O4, with a mass-normalized rate (k’) of 176.10 s−1·gAu-1 and a Turn Over Frequency (TOF) of 1757 h−1, being smaller than h-Au/PDA@Fe3O4 with a single-layer structure (k’ = 461.76 s−1·gAu-1, TOF = 6387 h−1), h-Au/PDA@PDA@Fe3O4 exhibits significantly superior stability compared to h-Au/PDA@Fe3O4. After undergoing 12 cycles of use, the conversion rate of h-Au/PDA@PDA@Fe3O4 decreased by only 4.3 %. After cyclic reaction, the conversion rate of h-Au/PDA@Fe3O4 decreased by as much as 64.8 %. The distinctive hollow double-layer structure of h-Au/PDA@PDA@Fe3O4, along with the interaction between Au and PDA, contributes significantly to its exceptional activity and stability. The research presented in this paper offers valuable insights and guidance for the suitable construction and industrial application of gold-based nano catalyst with good activity and cyclic stability.