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Silicon Nanocages for Selective Carbon Dioxide Conversion under Visible Light

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journal contribution
posted on 29.03.2019, 00:00 by Si Zhou, Xiaowei Yang, Wei Pei, Jijun Zhao, Aijun Du
Artificial photosynthesis for CO2 conversion to fuels and value-added chemicals is a tactic to close the anthropogenic carbon cycle. To this end, developing efficient catalysts composed of earth-abundant, economic, and eco-friendly elements is desirable but challenging. By comprehensive ab initio calculations, we show for the first time that caged silicon clusters doped by vanadium atom (VSin, n = 12–15) can catalyze CO2 hydrogenation to various C1 products (i.e., carbon monoxide, formic acid, formaldehyde, methanol, and methane) with kinetic barriers down to 0.67–1.53 eV and selectivity uniquely determined by cluster size and geometry. These clusters, which can be produced in laboratory with good stability, have suitable energy gap and can absorb sunlight from the visible to ultraviolet regime for driving the catalysis. Hence, these metal-doped Si clusters form a potential family of photocatalysts for selective CO2 hydrogenation. Their superior catalytic activity stems from the unsaturated states of the Si cage, which are mediated by sp-d hybridization and V–Si charge transfer. The CO2 adsorption strength is correlated with the coordination number and p orbital center of Si atoms. Such geometry–electronic structure–activity correlation should be applicable to the atomically precise design of novel silicon-based nanocatalysts for various renewable energy applications.