Silicon nanowires (SiNWs) were grown from n-Si(100) using a simple two-step metal-assisted chemical etching (MACE) approach with varying etching periods. Morphological, structural, and optical properties of prepared SiNWs were investigated. Solar illumination was used to evaluate the merits of n-Si(100) wafer and SiNWs photoanodes in photoelectrochemical (PEC) water splitting. SiNWs made by etching for 30 min exhibited a photocurrent density of 3.72 mA.cm-2 and a photoconversion efficiency (ƞ) of 1.37% at 0.78 volts under solar light. Cyclic voltammetry (CV) measurements were carried out, and the CV curves of the n-Si(100) wafer and n-SiNWs formed by various etching periods verified faradaic behavior with the formation of strong redox peaks. According to the results of electrochemical impedance spectroscopy (EIS), the charge transfer resistance of the SiNWs photoanode prepared by 30min of etching was 3112.3, which is low enough to facilitate interfacial charge transfer. At the working electrode/electrolyte interface, the Mott-Schottky (M-S) analysis revealed a high concentration of carriers of 4.77x1021cm-3.