Intrinsic Catalytic Activity of Gold/Multi-Walled Carbon Nanotubes Composites in Squaric Acid-Iron(II/III) System

In this paper, gold/multi-walled carbon nanotube (Au/MWCNTs) composites were prepared via in situ reductions. The synthesized materials could effectively catalyze the system of square acid (SQA)-iron(II/III) to produce a significant color reaction. By designing the orthogonal test of three-factor and three-level, the three factors of sodium formate solution concentration, ultrasonic time and synthesis reaction time were optimized in the process of Au/MWCNTs preparation. Results showed that the Au/MWCNTs had the best catalytic activity under the conditions of sodium formate solution concentration of 400 mmol/L, ultrasonic for 30 min and reaction for 4 h. In a subsequent comparison with H2O2, it found that the catalytic performance of 1 mg of Au/MWCNTs composite was equivalent to that of H2O2 with the concentration of 0.28 mmol/L. It demonstrated that the prepared Au/MWCNTs composites had good catalytic activity, stable color and low background noise, indicating a good prospect in various fields including that of catalytic reaction, sensing analysis, and nanomaterials labeling.