Pd Intercalation in BiOCl Nanosheets Promotes Ambient Electrosynthesis of Urea: Operando Study by Synchrotron X-ray Spectroscopies

High Resolution Image Download MS PowerPoint Slide Electrochemical urea synthesis offers an energy-efficient route for converting CO 2 and NO 3 – into a high-demand nitrogen commodity. However, urea selectivity hinges on orchestrating the coformation and interfacial coupling of CO 2 -derived *CO x and N-reduction *NH x intermediates. Consequently, achieving high urea rates and Faradaic efficiencies requires optimized catalyst designs. Here, we engineered 2D BiOCl nanosheets with Pd 0 to promote C–N coupling while suppressing H 2 evolution and Bi 0 segregation under negative potentials. We hydrothermally synthesized BiOCl and Pd-containing BiOCl nanosheets, both of which serve as electrocatalysts for the electrosynthesis of urea. Structural characterization confirmed that the Pd species are intercalated Pd 0 sub-nm clusters within the interlayers of the BiOCl nanosheets. The maximum Faradaic efficiency for urea reached 12.43 ± 1.02% over Pd–BiOCl and 6.99 ± 1.62% over BiOCl at −0.30 V vs RHE. Operando experiments were conducted using synchrotron powder X-ray diffraction and X-ray absorption spectroscopy, enabling real-time observation of phase transitions and local coordination environments. These results revealed that CO 3 2– intercalation occurred in both BiOCl and Pd-BiOCl nanosheets, leading to the formation of Bi 2 O 2 CO 3 . However, the layered framework of the nanosheets cracked at −0.5 V or at more negative potentials as Bi 0 segregated and aggregated into nanoclusters. In contrast, BiOCl nanosheets with intercalated Pd 0 subnm clusters avoided this issue over the range −0.1– −0.5 V. From these results, we conclude that intercalating Pd subnm clusters into BiOCl nanosheets stabilizes the layered framework, suppresses Bi 0 segregation, lowers the charge-transfer resistance, and enhances anion exchange toward urea production within the BiOCl interlayers.