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Mechanochemistry initiated the reaction of hydrogen-terminated porous silicon (H/por-Si) powder with arginine. Samples were analyzed using Fourier-transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), zeta potential, scanning electron microscopy (SEM), and photoluminescence (PL) spectroscopy. Arginine, which was physisorbed onto the surface of por-Si, blue-shifted the peak PL intensity from ~630 nm for the H/por-Si to ~565 nm for arginine-coated por-Si. Grinding for 4 h reduced >80% of the initially 2–45 µm particles to <500 nm, but was observed to quench the PL. With appropriate rinsing and centrifugation, particles in the 100 nm range were isolated. Rinsing ground powder with water was required to remove the unreacted arginine. Without rinsing, excess arginine induced the aggregation of passivated particles. However, water reacted with the freshly ground por-Si powder producing H2. A zeta potential of +42 mV was measured for arginine-terminated por-Si particles dispersed in deionized water. This positive value was consistent with termination such that NH2 groups extended away from the surface. Furthermore, this result was confirmed by FTIR spectra, which suggested that arginine was bound to silicon through the formation of a covalent Si–O bond.
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Response of Photoluminescence of H-Terminated and Hydrosilylated Porous Si Powders to Rinsing and Temperature
The photoluminescence (PL) response of porous Si has potential applications in a number of sensor and bioimaging techniques. However, many questions still remain regarding how to stabilize and enhance the PL signal, as well as how PL responds to environmental factors. Regenerative electroless etching (ReEtching) was used to produce photoluminescent porous Si directly from Si powder. As etched, the material was H-terminated. The intensity and peak wavelength were greatly affected by the rinsing protocol employed. The highest intensity and bluest PL were obtained when dilute HCl(aq) rinsing was followed by pentane wetting and vacuum oven drying. Roughly half of the hydrogen coverage was replaced with –RCOOH groups by thermal hydrosilylation. Hydrosilylated porous Si exhibited greater stability in aqueous solutions than H-terminated porous Si. Pickling of hydrosilylated porous Si in phosphate buffer was used to increase the PL intensity without significantly shifting the PL wavelength. PL intensity, wavelength and peak shape responded linearly with temperature change in a manner that was specific to the surface termination, which could facilitate the use of these parameters in a differential sensor scheme that exploits the inherent inhomogeneities of porous Si PL response.
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- Award ID(s):
- 1825331
- PAR ID:
- 10280060
- Date Published:
- Journal Name:
- Surfaces
- Volume:
- 3
- Issue:
- 3
- ISSN:
- 2571-9637
- Page Range / eLocation ID:
- 366 to 380
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3390/surfaces3030027
