Investigation of porous silicon thin films for electrochemical hydrogen storage
Highlights•Nanoporous silicon (PS) was elaborated by electrochemical anodization of p-type Si.•Electrochemical hydrogen storage capacity of Nano-PS was 86 mAh/g.•The hydrogen storage capacity decreases by the factor of 7% after 40 cycles.AbstractIn this study, nanoporous silicon (PS) layers have been elaborated and used for hydrogen storage. The effect of the thickness, porosity and specific surface area of porous silicon on the amount of hydrogen chemically bound to the nanoporous silicon structures is studied by Infrared spectroscopy (FTIR), cyclic voltammetry (CV), contact angle and capacitance –voltage measurements. The electrochemical characterization and hydrogen storage were carried out in a three-electrode cell, using sulfuric acid 3 M H2SO4 as electrolyte by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge/discharge. The results indicate the presence of two oxidation peaks at 0.2 V and 0.4 V on the anodic side corresponding to hydrogen desorption and a reduction peak at −0.2 V on the cathodic side corresponding to the sorption of hydrogen. Moreover, the EIS studies performed on PS electrode in 3 M H2SO4 show that the hodograph contains a semicircle at high frequency region and a line in the lower frequency zone. An equivalent circuit has been proposed; the values of the equivalent circuit elements corresponding to the experimental impedance spectra have been determined and discussed. Finally, the highest hydrogen storage in PS was 86 mAh/g. This storage capacity decreases by only 7% of the initial capacity value, after 40 cycles.
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