Abstract
The assembled state of nanoparticles (NPs) within porous matrices plays a governing role in directing their biological, electronic, and catalytic properties. However, the effects of the spatial confinement and environmental factors, such as salinity, on the NP assemblies within the pores are poorly understood. In this study, we use adsorption isotherms, spectrophotometry, and small-angle neutron scattering to develop a better understanding of the effect of spatial confinement on the assembled state and catalytic performance of gold (Au) NPs in propylamine-functionalized SBA-15 and MCM-41 mesoporous silica materials (mSiO2). We carry out a detailed investigation of the effect of pore diameter and ionic strength on the packing and spatial distribution of AuNPs within mSiO2 to get a comprehensive insight into the structure, functioning, and activity of these NPs. We demonstrate the ability of the adsorbed AuNPs to withstand aggregation under high salinity conditions. We attribute the observed preservation of the adsorbed state of AuNPs to the strong electrostatic attraction between oppositely charged pore walls and AuNPs. The preservation of the structure allows the AuNPs to retain their catalytic activity for a model reaction in high salinity aqueous solution, here, the reduction of p-nitrophenol to p-aminophenol, which otherwise is significantly diminished due to bulk aggregation of the AuNPs. This fundamental study demonstrates the critical role of confinement and dispersion salinity on the adsorption and catalytic performance of NPs.
Original language | English |
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Pages (from-to) | 2531-2541 |
Number of pages | 11 |
Journal | Journal of Physical Chemistry C |
Volume | 126 |
Issue number | 5 |
DOIs | |
State | Published - Feb 10 2022 |
Funding
Authors acknowledge Prof. K. Ding and Prof. W. A. Shelton for useful discussions. Acknowledgment is made to the Donors of the American Chemical Society Petroleum Research Fund for support of this research. This research used resources at the Spallation Neutron Source, DOE Office of Science User Facilities operated by the Oak Ridge National Laboratory. B.B. acknowledges the financial support by the National Science Foundation (NSF) under grant CBET-1943986 (NSF-CAREER).
Funders | Funder number |
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NSF-CAREER | |
National Science Foundation | CBET-1943986 |
Office of Science | |
Oak Ridge National Laboratory | |
American Chemical Society Petroleum Research Fund |