Time-Resolved Dynamics of Nitrate Electroreduction on Silver

As concerns over water eutrophication and wildlife preservation grow, nitrate electroreduction offers a promising route to close the nitrogen cycle by coupling wastewater pollution remediation with ammonia synthesis. Its coupling to green energy sources is tied to the development of highly active and selective electrocatalysts. Advancing this technology requires molecular-level insight into adsorption processes and dynamics under operating conditions. In this study, we use time-resolved surface-enhanced Raman spectroscopy (TR-SERS) to monitor NO3– and NO2– dynamics during nitrate reduction on roughened Ag electrocatalysts. Potential-dependent Raman shifts capture subtle changes in binding modes pertaining to NO3– reduction to NO2–. Theoretical calculations elucidate their preferred binding configurations under increasingly cathodic potentials and support the vibrational assignments. By resolving the real-time evolution of nitrate-derived species, TR-SERS provides valuable insight into their formation, transformation, and consumption pathways. This information is essential for the rational design of more efficient and selective electrocatalysts. Overall, this approach offers a powerful platform for mechanistic elucidation in nitrate reduction and can be readily extended to broader nitrogen-conversion chemistries.