Highly Selective CO₂ Electroreduction to CH₄ by In Situ Generated Cu₂ O Single-Type Sites on a Conductive MOF:...

It is still a great challenge to achieve high selectivity of CH₄ in CO₂ electroreduction reactions (CO₂ RR) because of the similar reduction potentials of possible products and the sluggish kinetics for CO₂ activation. Stabilizing key reaction intermediates by single type of active sites supported on porous conductive material is crucial to achieve high selectivity for single product such as CH₄ . Here, Cu₂ O(111) quantum dots with an average size of 3.5 nm are in situ synthesized on a porous conductive copper-based metal-organic framework (CuHHTP), exhibiting high selectivity of 73 % towards CH₄ with partial current density of 10.8 mA cm^-2 at -1.4 V vs. RHE (reversible hydrogen electrode) in CO₂ RR. Operando infrared spectroscopy and DFT calculations reveal that the key intermediates (such as *CH₂ O and *OCH₃ ) involved in the pathway of CH₄ formation are stabilized by the single active Cu₂ O(111) and hydrogen bonding, thus generating CH₄ instead of CO.