Mechanism of Water Splitting to Hydrogen by Silicon Carbide Nanoparticles

We report on the mechanism of water splitting to H₂ by silicon carbide nanoparticles through studying the grain surface evolution. It is elucidated that two different processes are actually involved in producing H₂, one being the photocatalytic reaction driven by SiC and the other one being a new pathway, that is, the direct chemical reaction between SiC and water. We show that H₂ can be detected even in dark by the latter process. Thin layers, consisting of silicon oxide or silicon oxycarbide, are found to form on the grain surface and retard further splitting to H₂ by photocatalysis. A possible reaction mechanism is put forward to understand the chemical behavior of SiC nanoparticles in water based on micro-structural analyses.