Silicon

Over the past decade, hydrogen gas generation has been a critical component toward clean energy due to its high specific energy content. Generating hydrogen gas from water is crucial for future applications, including space transportation. Recent studies show promising results using silicon nanoparticles (SiNPs) for spontaneous hydrogen generation, but most methods require external energy like high temperature or pressure. In this work, we investigated hydrogen production from SiNPs without external energy by leveraging high pH water using sodium hydroxide and optimizing the process with a microfluidic approach. When comparing the physical dispersion methods using the 0.1 mg/mL case, ultrasonic bath produced more hydrogen than magnetic stirrer. In this thesis, 0.01% dextran with pure SiNPs at concentrations of 0.1 mg/mL, 0.2 mg/mL, and 0.3 mg/mL was analyzed. The highest concentration with dextran generated at least 40% less hydrogen than silicon alone, thus dextran did not increase hydrogen gas.

The effect of silicon (Si) substitution on the structural properties of hydroxyapatite (HAp) is investigated with powder x-ray and neutron diffraction methods. For this purpose, a series of samples of pure hydroxyapatite and 0.4 wt % Si substituted hydroxyapatite were prepared following a precipitation method. Phase identification from x-ray powder diffraction measurements showed a single hydroxyapatite phase in all the samples. Powder neutron diffraction patterns from room temperature down to 15 K are analyzed using the Rietveld method. The refined lattice constants, interatomic distances and isotropic atomic displacement parameters as a function of temperature for the pure and substituted hydroxyapatite are compared.