Electrochemical CO2 reduction (ECR) into value-added multicarbon products is a promising approach for a carbon-neutral economy. Heterogeneous molecular catalysts consist of atomic-precise, controllable active sites with the potential to improve catalytic activity by ligand design and engineering, yet most reported molecular ECR catalysts do not exhibit multicarbon product selectivity. Herein, we report the use of a copper–supramolecular pair as a crystalline molecular catalyst to promote the formation of multicarbon products. A combination of experimental and theoretical studies reveal that the paired Cu sites work collaboratively to activate the CO2 substrate and facilitate the coupling of adsorbed CO species although they are not bonded or bridged directly. The van der Waals interactions between the substrate and the secondary coordination sphere also play a crucial role in multicarbon product selectivity.

The electrochemical reduction of CO 2 has been recognized as one of the best strategies to reduce atmospheric CO 2 levels and achieve a carbon-neutral economy. We report here a copper complex, Cu(salan) 2 , as an efficient CO 2 reduction catalyst in basic aqueous media. Cu(salan) 2 exhibited different catalytic behaviors in nanocrystalline and graphene-supported forms. As nanocrystals, the complex did not show high catalytic activity and gradually decomposed into Cu 2 O upon electrolysis. However, when dispersed on a graphene matrix, Cu(salan) 2 exhibited a moderate-to-high CO selectivity and remained stable in long-term electrolysis. This work shows that siteisolation by dispersion of a molecular catalyst is an effective way to increase the catalyst stability and tune the product selectivity for CO 2 RR electrocatalysis.

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