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- ISSN: 2210-6812
- E-ISSN: 2210-6820
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Recent Investigation of Spontaneous Ageing Effect on Electrochemical Behaviour of Porous Silicon using Cyclic Voltammetry
- Source: Nanoscience & Nanotechnology-Asia, Volume 15, Issue 3, Jun 2025, E22106812383673
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- 12 Feb 2025
- 03 Apr 2025
- 05 Jun 2025
Abstract
Introduction
Owing to its high surface area, tuneable porosity and unique electrochemical properties, porous silicon (PS) has been widely used in devices for electronics and biomedical applications. However, its long-term stability is compromised by spontaneous ageing, thus significantly impacting the performance, stability and reliability of PS-based devices.
Methods
In this study, PS layers with varying porosities (30%, 40%, and 50%) were obtained by electrochemical anodization of p-type silicon (100) in hydrofluoric acid (HF)–ethanol solutions. The samples were stored under ambient environmental conditions (open air, room temperature) for a period of 12 months to assess spontaneous ageing effects. Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Analysis (EDX) were used for structural and morphological changes. For electrochemical properties, Cyclic Voltammetry (C-V) was conducted in Potassium perchlorate (KClO4) and Phosphate-Buffered Saline (PBS) solutions.
Results
All fresh PS layers with different porosity exhibit a resistive behaviour. The aged PS at 40% porosity samples exhibited a distinct resistive behaviour in comparison with a capacitive response for other porosities aged samples (30% and 50%), confirming the spontaneous passivation of the PS surface. SEM analysis showed a reduction in pore size, where pores were completely sealed by an oxide layer.
Discussion
Our results suggest that ageing in PS is not solely driven by porosity, but by a complex interplay between pore structure, surface Chemistry and oxide layer formation. The unexpected resistive response at 40% porosity, where a dense oxide sealed the pores, challenges the assumption that higher or lower porosity alone governs stability. Our work shows that even in ambient conditions, spontaneous ageing significantly alters electrochemical behavior. These findings open new perspectives for improving PS surface treatments, though more research is needed to test other environments and time scales.
Conclusion
For the first time that this technique has been employed to assess the electrochemical changes induced by long-term storage under ambient conditions. Notably, our study demonstrates that the ageing –porosity is complex and that porosity is not the sole factor that influences the susceptibility of PS layers to environmental degradation. These findings offer valuable insights for researchers in order to develop surface passivation strategies to mitigate ageing effects, as to ensure the long-term stability of PS surfaces, enhancing their long-term functionality and maintaining optimal performance and durability.
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