Enhanced Electrocatalytic Activity of Primary Amines for CO2 Reduction Using Copper Electrodes in Aqueous Solution

Carbon dioxide (CO2) is an environmentally harmful “greenhouse gas” that is present in abundant quantities in the Earth’s atmosphere. Due to the stability of its structure, it is notoriously regarded as an inert molecule that will only react under harsh conditions such as high temperature or pressure. Electrochemical reduction of CO2 to value-added materials is a sustainable and potentially profitable way to curb greenhouse gas emissions; however, the challenge of amassing a sizable CO2 concentration in the active medium persists. Here, we find that various amines, already known to be effective absorbents for CO2 through the formation of carbamates, can be used directly as substrates for selectively reducing CO2 to carbon monoxide (CO) at room temperature and ambient pressure. Several primary amines were evaluated using glassy carbon and copper working electrodes for systematic comparison. Here, we demonstrated that use of copper electrodes dramatically enhances current density (up to −18.4 mA/cm2 at −0.76 V vs RHE) compared to glassy carbon electrodes (−0.63 mA/cm2) using ethylenediamine (EDA) as the catalyst. Moreover, the faradic efficiency was significantly increased from 2.3% to 58%. This concrete finding shows potential to enhance amine catalytic activity for efficient CO2 reduction. This research has introduced a potentially more sustainable and green method for carbon capture and reduction systems.