Electrochemical Preparation of Water-Reactive Silicon with Potential Applications in Hydrogen Generation

Abstract

On-site hydrogen generation from water by using silicon is of potential interest in fuel cell applications. However, mass production of water-reactive Si remains a challenge. This work indicates that Si prepared by molten salt electrolysis has potential applications in H2 production. Solid SiO2 powders were electrochemically converted to nano-sized Si wires in molten CaCl2. The electrolyzed Si wires rarely or slowly react with water at 25 °C, but react with water at 80 °C intensively with continuous gas formation. The results indicate that the electrolyzed Si is water-reactive, and the reactivity is sensitive to the water temperature. Such unique property is highly advantageous for safe handling of Si at room temperature as well as controllable generation of H2. This work suggests that molten salt electrolysis of solid SiO2 may be a solution for the mass production of water-reactive Si and subsequent H2 generation.