Regulating the Water Dissociation on Atomic Iron Sites to Speed Up CO<sub>2</sub> Protonation and Achieve pH‐Universal CO<sub>2</sub> Electroreduction
Qi Tang, Qi Hao, Junxiu Wu, Yaowen Zhang, Ping Sun, Depeng Wang, Chuan Tian, Haixia Zhong, Yihan Zhu, Keke Huang, Kai Liu, Xinbo Zhang, Jun Lü
Abstract
Abstract Atomic Fe sites enabled electrochemical carbon dioxide (CO 2 ) reduction (ECO 2 R) to carbon monoxide (CO) at low overpotentials. However, the narrow potential ranges for selective CO 2 conversion on atomic Fe sites hindered the CO production at high current densities. Therefore, unveiling the CO 2 electroreduction processes and clarifying the catalytic mechanisms on different atomic Fe sites are important for better design of atomic Fe catalysts toward efficient ECO 2 R. Herein, the ECO 2 R processes on single‐atom, dual‐atom, and cluster Fe sites are systematically investigated, and clarify that the balanced water dissociation and CO 2 protonation on dual‐atom Fe sites promote the efficient CO production. The dual‐atom Fe catalyst achieves Faradaic efficiencies of CO ( FE CO ) above 92% over a wide potential range of −0.4–−0.9 V versus reversible hydrogen electrode and maintains FE CO of 91% after 153‐h electrolysis in H‐type cell. Benefitting from the favorable CO 2 protonation for ECO 2 R on dual‐atom Fe sites, pH‐universal CO 2 electroreduction is achieved in alkali‐/acid‐/bicarbonate‐fed membrane electrode assembly electrolyzer, with FE CO exceeds 98% in strongly acidic/alkaline and neutral mediums. The work reveals a water dissociation‐promoted CO 2 electroreduction on dual‐atom Fe sites and presents a feasible regulation of atomic Fe sites for highly active/selective ECO 2 R.