Microenvironment Regulation Breaks the Trade-Off between the Faradaic Efficiency and the Current Density for Electrocatalytic Deuteration Using D2O

Abstract The high Faradaic efficiency (FE) of the deuteration of organics with D₂O at large current densities is significant for developing a feasible and promising room-temperature deuteration strategy. However, the FE and current density are the two ends of a seesaw because of the severe D₂ evolution side reaction at nearly industrial current densities (− 100 mA cm⁻ ²). Herein, we report a combined scenario of a nanotip-enhanced electric field and surfactant-modified interface microenvironment to enable electrocatalytic deuteration of arylacetonitrile in D₂O with an 80% FE at − 100 mA cm⁻ ², which are both the best records for electrocatalytic deuteration. The increased reactant concentration with low activation energy due to the large electric field along the tips and the accelerated reactant transfer and suppressed D₂ evolution by the surfactant-created deuterophobic microenvironment contribute to breaking the trade-off between high FE and current density. Furthermore, the application of our strategy in other deuteration reactions with improved FE at − 100 mA cm⁻ ² rationalizes the design concept.