Heterogeneous Reduction of CO2 By Hydride-Terminated Silicon Nanocrystals

Silicon, the second most plentiful element after oxygen, constitutes 28% of the earth’s mass. Its high abundance, lack of toxicity and low cost coupled with its unique electrical and optical properties, crowns elemental silicon the king of semiconductors for converting sunlight into electricity. Clearly, in the quest for a semiconductor that can make chemicals and fuels from sunlight and carbon dioxide it would be advantageous if silicon could fulfill this role but unfortunately the best performers are invariably made from rare and expensive elements. Herein we report the unprecedented observation that hydride-terminated silicon nanocrystals, denoted ncSi:H, can function as a single component heterogeneous reducing agent for converting gaseous CO₂ selectively to CO, at an impressive rate of hundreds of micromol/h∙g. The large surface area, broadband visible to near infrared light harvesting and reducing power of SiH surface sites of ncSi:H play key roles in the conversion of CO₂ to CO.