Preparation of Well-dispersed Silver Nanoparticles Modified Silica Composite Structures and their Efficient Catalytic Reduction of p-nitrophenol

Introduction: Silver nanoparticles decorated silica (SiO2/AgNPs) were first synthesized by the chemical reduction method, and their heterogeneous catalytic performance was analyzed in detail. Methods: By transmission electron microscopy (TEM), scanning electron microscopy (SEM), and ultraviolet-visible spectra (UV-vis), the small particle size silver nanoparticles (AgNPs) adhere to the surface of silicon dioxide uniformly when adding 1 mL of 40 mM silver nitrate (AgNO3) and using 400 μL of 0.1 M sodium citrate. Uniformly loading silver nanoparticles on the surface of silica is one of the key problems we have already solved, and the uniform particle size is 6.05 ± 0.31 nm. results: Silver nanoparticles decorated silica (SiO2/AgNPs) have been synthesized by chemical reduction method, and their properties were analyzed in detail. By transmission electron microscopy (TEM), scanning electron microscopy (SEM) and ultraviolet-visible spectra (UV-vis), the small particle size silver nanoparticles adhere to the surface of silicon dioxide uniformly when adding 1 mL of 40 mM silver nitrate (AgNO3) and using 400 μL of 0.1 M sodium citrate. Results: Compared with silver ammonia complex as silver precursor, AgNPs formed by AgNO3 have more uniform adhesion, smaller particle size, and wider coverage. The main reason is believed to be that the nucleation rate of the formed AgNPs and the pH of the solution are important factors affecting the uniformity of adhesion. Therefore, the surface modification of SiO2 and the slow nucleation of AgNPs are the key steps in preparing the SiO2/AgNPs composite and also important factors in ensuring the uniform dispersion of AgNPs. Discussion: The heterogeneous catalytic reduction of p-nitrophenol (4-nitrophenol, 4-NP) with SiO2/AgNPs composite nanostructure showed a high catalytic effect, and the reaction rate constant and the turnover frequencies (TOF) reached 4.833×10-3 s-1 and 127 h-1, respectively. We analyzed the mechanism of catalysis and compared it with other similar catalysts. Conclusion: These research results indicate that SiO2/AgNPs composite materials have advantages in terms of cost, ease of synthesis, and catalytic turnover. We expect that the preparation method will be universal in the field of precious metal/semiconductor composites, and this composite structure will have a wider range of applications in the removal of water pollutants and environmental protection.