Unique hole-accepting carbon-dots promoting selective carbon dioxide reduction nearly 100% to methanol by pure water

Abstract

Solar-driven CO ₂ reduction by abundant water to alcohols can supply sustainable liquid fuels and alleviate global warming. However, the sluggish water oxidation reaction has been hardly reported to be efficient and selective in CO ₂ conversion due to fast charge recombination. Here, using transient absorption spectroscopy, we demonstrate that microwave-synthesised carbon-dots ( ^mCD) possess unique hole-accepting nature, prolonging the electron lifetime ( t _50%) of carbon nitride (CN) by six folds, favouring a six-electron product. ^mCD-decorated CN stably produces stoichiometric oxygen and methanol from water and CO ₂ with nearly 100% selectivity to methanol and internal quantum efficiency of 2.1% in the visible region, further confirmed by isotopic labelling. Such ^mCD rapidly extracts holes from CN and prevents the surface adsorption of methanol, favourably oxidising water over methanol and enhancing the selective CO ₂ reduction to alcohols. This work provides a unique strategy for efficient and highly selective CO ₂ reduction by water to high-value chemicals.

Abstract

Solar-driven CO2 reduction by abundant water to alcohols is hindered by the sluggish water oxidation reaction. Here, the authors demonstrate that the microwave-synthesized carbon-dots possess unique hole-accepting nature, allowing stoichiometric oxygen and methanol production from water and CO2 with nearly 100% selectivity to methanol.