Photocatalytic Method for the Simultaneous Synthesis and Immobilization of Ag Nanoparticles onto Solid Substrates

• Published in: Journal of physical chemistry. C Vol. 122; no. 42; pp. 24110 - 24119
• Main Authors: Costa, Ítalo A, Maciel, Ayessa P, Sales, Maria José A, Rivera, Luis Miguel R, Soler, Maria A. G, Pereira-da-Silva, Marcelo A, Moreira, Sanclayton G. C, Paterno, Leonardo G
• Format: Journal Article
• Language: English
• Published: American Chemical Society 25-10-2018
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.8b07081

A photocatalytic method based on layer-by-layer photocatalyst films made of titanium dioxide nanoparticles and graphene oxide, TiO2NPs/GO, is proposed for performing the synthesis and immobilization of spherical AgNPs simultaneously using diluted AgNO3 solutions and UV irradiation (254 nm). The novelty provided by this method is that the amount and aggregation extent of AgNPs can be controlled by the number of TiO2NP/GO bilayers and the composition of the outermost layer in the photocatalyst film. When the outermost layer is made of GO, more AgNPs are deposited because GO serves as an anchoring harbor for Ag+ ions and a venue to the transportation of photoexcited electrons for subsequent photo reduction to Ag0. The photodeposition follows a first-order kinetics, whereas in the equilibrium it can be fitted by the Langmuir isotherm model for which surface coverage as high as 60% is attained after 70 min of UV irradiation. The TiO2NP/GO/AgNP substrates show surface-enhanced resonant Raman scattering (SERRS) activity for nickel­(II) phthalocyanine-tetrasulfonic acid tetrasodium salt (NiTsPc). The SERRS activity is ascribed to a combination of local electromagnetic field enhancement because of the plasmon resonance of AgNPs and proper excitation of samples in resonance with the Q-band of NiTsPc.