Understanding the Roles of Hydroxide in CO₂ Electroreduction on a Cu Electrode for Achieving Variable Selectivity

Abstract

Hydroxide-derived copper (OH/Cu) electrodes exhibit excellent performance for the electrocatalytic CO2 reduction reaction (CO2RR). However, the role of hydroxide (OH) in CO2RR remains controversial; therefore, the origin of the selectivity enhancement emerging on OH/Cu has not been fully understood. In the present work, we quantitatively evaluated surface OH by electroadsorption and established a direct correlation between the OH amount and selectivity for the production of CH4 and C2+ on OH/Cu with the help of computational investigations concerning work functions of the surface. Based on these findings, we demonstrated variable selectivity using OH/Cu electrodes having a controlled OH amount; three OH/Cu electrodes realized their distinct selectivity such as Faradic efficiency (FE) for the production of CH4 (CH4 FE) of 78%, C2+ FE of 71%, and the ratio of C2+-to-CH4 >355. The proposed simple strategy for selectivity control would contribute to further quantity synthesis of value-added chemicals using CO2RR.

Asymmetric Low-Frequency Pulsed Strategy Enables Ultralong CO2 Reduction Stability and Controllable Product Selectivity

“…The bending peak of adsorbed water decreased with the anodic pulse and increased under the cathodic conditions. This phenomenon was possibly related to the local changes of the adsorbed OH species . The OH species played an important role in controlling CO 2 RR products, which also impacted the local pH.…”

“…This phenomenon was possibly related to the local changes of the adsorbed OH species. 42 The OH species played an important role in controlling CO 2 RR products, which also impacted the local pH. Therefore, we employed the in situ Raman experiment to explore the local pH (Figures S32 and S33).…”

Understanding the complexity in bridging thermal and electrocatalytic methanation of CO2

“…Recent results show that hydroxide-derived copper electrodes exhibit excellent performance in the electrocatalytic CO 2 reduction reaction. 56 Based on the OH/Cu ratio in the electrode, excellent faradaic efficiencies for CH 4 (78%) or C 2+ products (71%) are observed. Most mechanistic indications and factors determining the surface path are invalid for these electrocatalysts.…”

“…There is often a drastic reconstruction during electrocatalysis not corresponding to a change in the behaviour as expected from these mechanistic indications. 326 Sun et al 56 showed that hydroxide-derived copper (OH/Cu) electrodes are active in CO 2 methanation. Copper phosphate nanosheets also offer high performances.…”

Decreased spin-resolved anti-bonding states filling to accelerate CHO conversion into CH2O in transitional metal-doped Mo2C monolayers during CO2 reduction

“…Different catalysts such as Cu-based electrocatalysts, noble metals, and their derived electrocatalysts have been reported for CO 2 electro-reduction. [6][7][8] Recently, a new class of twodimensional (2D) transition metal (TM) carbides, nitrides and carbonitrides (collectively known as MXenes) have remarkable potential applications in numerous electrochemical processes. [9][10][11][12][13][14][15][16] The special metallic electronic structure will give rise to effective electron transport, and the abundant TM atoms with empty d-orbitals are benecial for the activation of gasphase molecules; thus, MXenes have attracted considerable attention in recent years.…”