Bibliographic citations
Obregón, D., (2022). Estudio del desempeño de semiconductores basados en silicio como fotocátodos para la obtención de hidrógeno en procesos de electrólisis fotoasistida [Pontificia Universidad Católica del Perú]. http://hdl.handle.net/20.500.12404/22839
Obregón, D., Estudio del desempeño de semiconductores basados en silicio como fotocátodos para la obtención de hidrógeno en procesos de electrólisis fotoasistida []. PE: Pontificia Universidad Católica del Perú; 2022. http://hdl.handle.net/20.500.12404/22839
@mastersthesis{renati/12500,
title = "Estudio del desempeño de semiconductores basados en silicio como fotocátodos para la obtención de hidrógeno en procesos de electrólisis fotoasistida",
author = "Obregón Valencia, Daniel Cristopher",
publisher = "Pontificia Universidad Católica del Perú",
year = "2022"
}
Hydrogen can be obtained by electrolysis of water by applying external electric current, which implies relatively high-energy costs. Peru is located in one of the regions with the highest incidence of solar radiation in the world. This abundant and renewable energy can be used to assist the electrolysis process of water in the so-called photoelectrochemical cells (PEC). This requires the use of semiconductor materials as electrodes, which can produce photocurrent based on their optoelectronic properties and chemical stability. In this research, the performance of boron-doped (p-type) crystalline silicon with different electrical resistivities as photocathodes for hydrogen production in a PEC is studied. The focus of the study is to evaluate the influence of SiO2 formation on hydrogen photocurrent production in acidic electrolytes. The p-Si samples were subjected to chemical treatment in HF 10% and then evaluated in PECs by open circuit potential monitoring technique, and under an intermittent standard AM1.5G lighting, produced by a solar simulator with a xenon lamp, by linear sweep voltammetry, and chronoamperometry techniques. Properties such as flat-band potential and doping concentration were also characterized by electrochemical impedance spectroscopy and Mott-Schottky analysis. Using linear sweep voltammetry tests on the p-Si (100) samples with resistivity of 0.001-0.005 Ω cm it was found an onset potential of -0.30 V vs. Ag/AgCl KCl 3M. In addition, a maximum photocurrent density of -16 mA cm-2 was found with chemical treatment with HF solution at 10% in comparison to -0.5 mA cm-2 in sample without chemical treatment. Likewise, chronoamperometry tests were carried out under intermittent light for 3 hours a day for 3 consecutive days. The characterization of these samples using scanning electron microscopy, energy disperse X-ray spectroscopy, and ellipsometry confirmed the formation of a thicker oxide layer (15 nm) in the samples that were immersed in a solution purged with air, i.e., electrolyte solutions with a higher presence of dissolved oxygen. An average reduction in photocurrent density from -15 mA cm-2 to -3 mA cm-2 was attributed to oxide formation on sample surface.
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