Boosting Electrochemical Urea Synthesis via Constructing Ordered Pd–Zn Active Pair

Abstract

Highlights

Ordered intermetallic pallium-zinc (PdZn) electrocatalyst comprising a high density of PdZn pairs is synthesized for achieving co-adsorption and co-activation carbon dioxide and nitrate.

Both operando measurements and theoretical calculations reveal that the PdZn pairs provide a dual-site geometric structure conducive to the key C–N coupling with a low kinetical barrier.

The intermetallic PdZn displays excellent performance for the co-reduction of nitrate (NO₃^–) and carbon dioxide (CO₂) toward urea, with a maximum FE_urea of 62.78% at a small potential of – 0.4 V versus RHE.

Electrochemical co-reduction of nitrate (NO₃^–) and carbon dioxide (CO₂) has been widely regarded as a promising route to produce urea under ambient conditions, however the yield rate of urea has remained limited. Here, we report an atomically ordered intermetallic pallium-zinc (PdZn) electrocatalyst comprising a high density of PdZn pairs for boosting urea electrosynthesis. It is found that Pd and Zn are responsible for the adsorption and activation of NO₃^– and CO₂, respectively, and thus the co-adsorption and co-activation NO₃^– and CO₂ are achieved in ordered PdZn pairs. More importantly, the ordered and well-defined PdZn pairs provide a dual-site geometric structure conducive to the key C–N coupling with a low kinetical barrier, as demonstrated on both operando measurements and theoretical calculations. Consequently, the PdZn electrocatalyst displays excellent performance for the co-reduction to generate urea with a maximum urea Faradaic efficiency of 62.78% and a urea yield rate of 1274.42 μg mg^–1 h^–1, and the latter is 1.5-fold larger than disordered pairs in PdZn alloys. This work paves new pathways to boost urea electrosynthesis via constructing ordered dual-metal pairs.