Shape-selective catalysis and surface enhanced Raman scattering studies using Ag nanocubes, nanospheres and aggregated anisotropic nanostructures.
Three morphologies of silver nanoparticles (Ag NPs) such as nanocubes, aggregated anisotropic Ag NPs, and nanospheres were prepared using polystyrene sulfonate (PSS) and citrate as stabilizing agents utilizing a simple wet-chemical and microwave heating route respectively. Ag nanocubes were prepared within one min through microwave heating whereas anisotropic Ag NPs and spherical Ag NPs via 5 and 30min of normal stirring at room temperature (RT) respectively. The shape effect of three different morphologies of Ag NPs were examined in catalysis reaction and in surface enhanced Raman scattering (SERS) studies. For catalysis experiments, reduction of various nitroaromatics was done taking excess NaBH4in presence of those morphologically different Ag NPs as catalyst and the corresponding catalytic activity is ordered as: Ag nanospheres>aggregated anisotropic Ag NPs>Ag nanocubes. The highest catalytic rate of ∼1.34×10-1min-1was observed with citrate capped Ag nanospheres. SERS study was done taking methylene blue (MB) as the Raman probe where a highest enhancement factor (EF) of ∼1.05×107was observed with Ag nanospheres and the order of EF values is as follows: Ag nanospheres>Ag nanocubes>aggregated anisotropic Ag NPs. The highest catalytic and SERS activity of citrate stabilized spherical Ag NPs are attributed due to the fast electron transfer in catalysis and creation of more number of surface active 'hot spots' in SERS studies. In future, the overall process we highlighted here might found potential application for the preparation of other varieties of nanomaterials applicable to catalysis reaction and in SERS-based trace analysis of various biologically important molecules and fine chemicals.
Department of Materials Science and Engineering, Texas A&M University, College Station, TX 77843, USA; Electrochemical Materials Science (ECMS) Division, CSIR-Central Electrochemical Research Institute (CECRI), Karaikudi 630006, Tamil Nadu, India. Electronic address: skundu@tamu.edu.
Subrata
S
Kundu
Department of Mechanical Engineering, Texas A&M University, College Station, TX 77843, USA.
Wei
W
Dai
Department of Materials Science and Engineering, Texas A&M University, College Station, TX 77843, USA.
Yunyun
Y
Chen
Department of Mechanical Engineering, Texas A&M University, College Station, TX 77843, USA.
Lian
L
Ma
Department of Materials Science and Engineering, Texas A&M University, College Station, TX 77843, USA.
Yuan
Y
Yue
Department of Physics and Astronomy, Texas A&M University, College Station, TX 77843, USA.
Alexander M
AM
Sinyukov
Department of Materials Science and Engineering, Texas A&M University, College Station, TX 77843, USA. Electronic address: hliang@tamu.edu.
Hong
H
Liang
Catalysis; Microwave heating; Nanocubes; Nanospheres; SERS; Shape-selective