Self-Reconstruction of Core-Shell Structured Electrocatalysts for Tailoring Reaction Pathways Revealed by Electrochemical Surface-Enhanced Raman Spectroscopy

The electrocatalysts undergo structural reconstruction during electrocatalytic reactions, accompanied by significant variations in the catalytic activity and selectivity. However, it is still challenging to track in situ structural evolution and reaction process simultaneously to further figure out the origin of the surface reconstruction and its correlation to the electrocatalytic performance. By utilizing the species involved in formic acid electrooxidation reaction (FAER) as probe molecules, we employed electrochemical surface-enhanced Raman spectroscopy (EC-SERS) to reveal that the surface reconstruction process occurred on Au core-Pt shell nanoparticles (Au@Pt NPs). Via potential-dependent Raman features, we clearly revealed that the Au atoms from the Au core can migrate to the ultrathin Pt shell during FAER. Importantly, in situ SERS spectra showed that the reconstruction of Au@Pt NPs originated from the CO produced during the electrocatalytic process. We further showed that this structural transformation reduces the CO binding strength on Pt surfaces and tailors the reaction pathways of the FAER, thus facilitating the pathway of direct dehydrogenation of formic acid to CO2 by 2.6 times. This work demonstrates the importance of structural evolution of electrocatalysts during the reaction process to the catalytic performance, providing insight for designing highly efficient and robust electrocatalysts.