Fig. 2 UV-vis spectra of different combinations after 10 min of reaction at room temperature.
The impact of various factors, including pH, temperature, catalyst concentration and reaction time. On the catalytic abilities of R12-AgNPs was further explored using UV-Vis absorption spectra. To determine the optimal pH value, absorption spectra were recorded across a pH range from 3 to 8 (Fig. 3A). It was observed that the absorption peak at 652 nm was absent at pH 8, whereas the highest absorbance at this peak was attained at pH 4. Therefore, the optimum reaction pH of R12-AgNPs was determined to be pH=4, consistent with the previous report [43]. In addition, the absorbance values increased with rising temperature and reached peaked at 50 ℃ (Fig. 3B). However, a decline in the concentration of ox-TMB was noticed at higher temperature (60 ℃), which may be attributed to the reduced thermal stability of H2O2 in an acidic environment [20]. The effect of catalyst concentration was analyzed by adding AgNPs in the range of 0-100 μL to the solution. The results in Fig. 3C indicated that the catalytic activity of TMB oxidation increased with a higher catalyst concentration, with the highest absorbance at the 652 nm peak occurred at 100 μL of R12-AgNPs solution was used. Finally, the changes in catalytic activity over to the course of the reaction time were demonstrated in Fig. 3D, revealing the maximum catalytic activity was achieved within 10 min. Consequently, the optimal conditions for maximum catalytic activity in the oxidation of TMB were discovered to be at a pH of 4, a temperature of 50 ℃, 100 μL of AgNPs, and a reaction time of 10 min.