Unraveling the Mechanism for the Sharp-Tip Enhanced Electrocatalytic Carbon Dioxide Reduction: The Kinetics Decide

The electrocatalytic reduction reaction of carbon dioxide can be significantly enhanced by the use of a sharp-tip electrode. However, the experimentally observed rate enhancement is many orders of magnitudes smaller than what would be expected from an energetic point of view. The kinetics of this tip-enhanced reaction are shown to play a decisive role, and a novel reaction-diffusion kinetic model is proposed. The experimentally observed sharp-tip enhanced reaction and the maximal producing rate of carbon monoxide under different electrode potentials are well-reproduced. Moreover, the optimal performance shows a strong dependence on the interaction between CO2 and the local electric field, on the adsorption rate of CO2, but not on the reaction barrier. Two new strategies to further enhance the reaction rate have also been proposed. The findings highlight the importance of kinetics in modeling electrocatalytic reactions.