Influence of deposition temperature on the structure and catalytic properties of the copper nanotubes composite membranes

Abstract

In recent years the unique properties of copper nanostructures are the subject of numerous studies in various areas of material science. In this paper, we studied the features of the electroless template synthesis of copper nanotubes (Cu NTs) in the nanoporous poly(ethylene terephthalate) track-etched membranes (PET TeMs) under various temperature deposition regimes. The structure and the chemical composition of the obtained composite membranes were studied by the methods of gas permeability, scanning electron microscopy, energy dispersive analysis and x-ray diffraction. The effect of deposition temperature on the catalytic properties of Cu NT in a polymer matrix was studied using the benchmark reaction of the reduction of p-nitrophenol (4-NP). The highest rate constant of the 4-NP reduction reaction was established for composites synthesized at 10 °C. This temperature regime of synthesis makes it possible to obtain strong thin-walled Cu NTs in the pores of PET TeMs and the 4-NP conversion degree after 6 consistent runs of the composite catalyst decreases by 20%, while for samples deposited at 25 °C the conversion index decreases by more than 40%. To study the kinetic parameters of the reaction in a temperature range of 16 °C–40 °C, the activation energies found from the Arrhenius plots were 35.3 and 61.3 kJ mol−1 for the reaction over catalysts synthesized at the 2 and 25 °C, respectively, and 28.32 kJ mol−1 for the samples deposited at the 10 °C. The results indicate a high potential of composite catalysts based on the PET TeMs with embedded copper NTs for 4-NP removal.