Solar Driven CO2 Hydrogenation on Ti-Doped Silicon Nanocages

Hydrogenation of carbon dioxide (CO2) to produce fuels and value-added chemicals is a critical reaction to solve both energy and environment issues. Developing efficient catalysts composed of earth-abundant, cost-effective and eco-friendly elements is highly desired but remains challenging. Here, we exploit titanium-doped silicon cage nanoclusters (TiSin, n = 12-16) for CO2 hydrogenation. Our first-principles calculations show that the activity and product selectivity of TiSin clusters exhibit remarkable size-dependences, and they can also absorb a large portion of sun light from visible to ultraviolet regimes to drive the catalysis. Their activity origins from the unsaturated electronic states on the silicon cage, mediated by the strong covalent bonding between Si and Ti atoms. More importantly, we establish a relationship between binding capability of TiSin clusters and the p orbital center of silicon cage, which provide general guidelines for atomically precise design of not only silicon-based clusters but also other non-metal catalysts for highly active and selective CO2 conversion.