title: Millifluidics for time-resolved mapping of the growth of gold nanostructures.
abstract: Innovative in situ characterization tools are essential for understanding the reaction mechanisms leading to the growth of nanoscale materials. Though techniques, such as in situ transmission X-ray microscopy, fast single-particle spectroscopy, small-angle X-ray scattering, etc., are currently being developed, these tools are complex, not easily accessible, and do not necessarily provide the temporal resolution required to follow the formation of nanomaterials in real time. Here, we demonstrate for the first time the utility of a simple millifluidic chip for an in situ real time analysis of morphology and dimension-controlled growth of gold nano- and microstructures with a time resolution of 5 ms. The structures formed were characterized using synchrotron radiation-based in situ X-ray absorption spectroscopy, 3-D X-ray tomography, and high-resolution electron microscopy. These gold nanostructures were found to be catalytically active for conversion of 4-nitrophenol into 4-aminophenol, providing an example of the potential opportunities for time-resolved analysis of catalytic reactions. While the investigations reported here are focused on gold nanostructures, the technique can be applied to analyze the time-resolved growth of other types of nanostructured metals and metal oxides. With the ability to probe at least a 10-fold higher concentrations, in comparison with traditional microfluidics, the tool has potential to revolutionize a broad range of fields from catalysis, molecular analysis, biodefense, and molecular biology.
authors.affiliation: Center for Advanced Microstructures and Devices, Louisiana State University, Baton Rouge, Louisiana 70806, USA.
authors.forename: Katla
authors.initials: K
authors.lastname: Sai Krishna
authors.forename: Chelliah V
authors.initials: CV
authors.lastname: Navin
authors.forename: Sanchita
authors.initials: S
authors.lastname: Biswas
authors.forename: Varshni
authors.initials: V
authors.lastname: Singh
authors.forename: Kyungmin
authors.initials: K
authors.lastname: Ham
authors.forename: G Lisa
authors.initials: GL
authors.lastname: Bovenkamp
authors.forename: Chandra S
authors.initials: CS
authors.lastname: Theegala
authors.forename: Jeffery T
authors.initials: JT
authors.lastname: Miller
authors.forename: James J
authors.initials: JJ
authors.lastname: Spivey
authors.forename: Challa S S R
authors.initials: CS
authors.lastname: Kumar