Preparation of pSi: PSi powders were produced from the electrochemical etching of single crystalline (FZ) 30 – 50 Ω.cm p-type Si wafer. The etching parameters are similar to the process developed to produce powders whose surface area exceeds 1000 m²/g and described in a previous publication.1 The electrolyte was composed of highly concentrated hydrofluoric acid (HF – 30 wt. %) mixed with sulfuric acid (38 wt. %). The porous silicon layer was formed by anodization under galvanostatic control (65 mA/cm²) for 108 seconds using a Keithley 2400 as source. After anodization, the porous powders were first lifted off the parent substrate thanks to a second anodization step (65 mA/cm² for 30 seconds) in dilute HF (3 wt%) in isopropyl alcohol (IPA 10 wt%) solution, the powders were then collected and carefully rinsed in IPA.
