Cu^δ+ Site-Enhanced Adsorption andCrown Ether-Reconfigured Interfacial D₂O Promote ElectrocatalyticDehalogenative Deuteration

Electrocatalytic dehalogenative deuteration is a sustainable method for precise deuteration, whereas its Faradaic efficiency (FE) is limited by a high overpotential and severe D₂ evolution reaction (DER). Here, Cu^δ+ site-adjusted adsorption and crown ether-reconfigured interfacial D₂O are reported to cooperatively increase the FE of dehalogenative deuteration up to 84% at −100 mA cm^–2. Cu^δ+ sites strengthen the adsorption of aryl iodides, promoting interfacial mass transfer and thus accelerating the kinetics toward dehalogenative deuteration. The crown ethers disrupt the hydration effect of K·D₂O and reconstruct the hydrogen bond with the interfacial D₂O, lowering the content K·D₂O of the electric double layer and hindering the interaction between D₂O and the cathode, thus inhibiting the kinetics of the competitive DER. A linear relationship between the matched sizes of crown ethers and alkali metal cations is demonstrated for universally increasing FEs. This method is also suitable for the deuteration of various halides with high easily reducible functional group compatibility and improved FEs at −100 mA cm^–2.