Preparation And Researches Of Polydopamine Composite Surfaces

Metal nanoparticles-polydopamine composite materials are a new kind of materials,which possess the advantages of simple preparation method and good catalytic performance and attract more and more attention of scientific researchers.Composite materials of polydopamine and gold nanoparticles?NPs?on glass substrates?Au/PDA@slides?were obtained via a simple chemical process:first,polydopamine films?PDA@slides?were formed by immersing slides in dopamine aqueous solution at pH 8.5 for 1 h.Then the PDA@slides were dipped in 0.02 mol·L^-1 chloroauric acid?HAuCl₄?aqueous solution for certain time,Au/PDA@slides were formed.Gold NPs were obtained by the reductive properties of polydopamine.The morphology and chemical composition of the composite material were characterized using scanning electron microscopy,X-ray diffraction pattern and X-ray photoelectron spectroscopy.The catalytic properties of the Au/PDA@slides were evaluated by the reduction of 4-nitrophenol?4-NP?in the presence of sodium borohydride?NaBH₄?aqueous solution at room temperature.The catalytic activity of the optimal Au/PDA@slide was so satisfactory that the reduction of4-NP was completed within 10 min,which was obtained when PDA@slide was immersed in 0.02 mol·L^-11 HAuCl₄ aqueous solution for 2 h.Moreover,the Au/PDA@slide composite material was stable up to 5 cycles without a significant loss of its catalytic activity.In addition,the Au/PDA@slide also exhibit photocatalytic ability,which can photodegrade methyl orange.By measuring the UV-Vis absorption bonds of Au/PDA@slides,it proved that the condition of the strongest surface plasmon resonance of Au/PDA@slides is the optimal condition of catalytic reduction of 4-NP.In this work,Ag/polydopamine composite on glass substrates?Ag/PDA@slides?were formed by using polydopamine?PDA?as both reducing and stabilizing agent to reduce silver salts to silver nanoparticles?NPs?and adhesive them to slides.The morphology and chemical composition of the composite material was characterized by scanning electron microscopy?SEM?and X-ray diffraction pattern?XRD?.The prepared Ag/PDA@slide was a highly active catalyst for the reduction of 4-nitrophenol?4-NP?in the presence of sodium borohydride?NaBH₄?aqueous solution at room temperature.The reduction rate of the optimal catalyst was as fast as 10 s and it was stable up to 6 cycles without a significant loss of its catalytic activity.By measuring the UV-Vis absorption bonds of Ag/PDA@slides,it proved that condition of the strongest surface plasmon resonance of Ag/PDA@slides is the optimal condition of catalytic reduction of 4-NP.