Efficient and Selective CO 2 Reduction to Formate on Pd-Doped Pb 3 (CO 3 ) 2 (OH) 2 : Dynamic Catalyst Reconstruction and Accelerated CO 2 Protonation.

Exploring catalyst reconstruction under the electrochemical condition is critical to understanding the catalyst structure-activity relationship as well as to design effective electrocatalysts. Herein, a PbF 2 nanocluster is synthesized and its self-reconstruction under the CO 2 reduction condition is investigated. F - leaching, CO 2 -saturated environment, and application of a cathodic potential induce self-reconstruction of PbF 2 to Pb 3 (CO 3 ) 2 (OH) 2 , which effectively catalyze the CO 2 reduction to formate. The in situ formed Pb 3 (CO 3 ) 2 (OH) 2 discloses >80% formate Faradaic efficiencies (FEs) across a broad range of potentials and achieves a maximum formate FE of ≈90.1% at -1.2 V versus reversible hydrogen electrode (RHE). Kinetic studies show that the CO 2 reduction reaction (CO 2 RR) on the Pb 3 (CO 3 ) 2 (OH) 2 is rate-limited at the CO 2 protonation step, in which proton is supplied by bicarbonate (HCO 3 - ) in the electrolyte. To improve the CO 2 RR kinetics, the Pb 3 (CO 3 ) 2 (OH) 2 is further doped with Pd (4 wt%) to enhance its HCO 3 - adsorption, which leads to accelerated protonation of CO 2 . Therefore, the Pd-Pb 3 (CO 3 ) 2 (OH) 2 (4 wt%) reveals higher formate FEs of >90% from -0.8 to -1.2 V versus RHE and reaches a maximum formate FE of 96.5% at -1.2 V versus RHE with a current density of ≈13 mA cm -2 .