Accelerated Discovery-to-Unveiling of High-Performance and Affordable Ammonia Electrode Process by Human-Machine...

The electrochemical nitrate reduction reaction (eNO₃RR) to ammonia (NH₃) is a key for producing fuels during interstellar travel and an alternative to Haber-Bosch process. However, the complicated multi-electron/proton transfer electrode process of eNO₃RR makes affordable electrocatalyst discovery and its mechanistic understanding challenging. Herein, we established a human-machine collaboration framework by employing dimensionally reduced reaction descriptors which enables an accelerated data-driven discovery-to-unveiling of unconventional and high-performance eNO₃RR electrocatalysts with desirable element choice. Using the current density difference between nitrite (NO₂ ^-) reduction and hydrogen evolution as a descriptor, the optimal FeCoNiCuGa electrocatalyst was identified in a drastically short timeframe. Even compared with Pt or Rh, the FeCoNiCuGa exhibits a higher NH₃ production rate of 9.8 mmol mg_cat ^-1 at -0.3 V versus a reversible hydrogen electrode. Furthermore, together with a mechanistic study using rotating ring-disk electrode combined with a new kinetic model, in situ infrared spectroscopy unveiled that the adsorbed NO₂ ^- (*NO₂ ^-) plays a crucial role in the efficient electrode process: a moderate *NO₂ ^- binding accelerates NH₃ formation whereas a weak binding leads to unfavorable reactions. Our work demonstrates that a comprehensive human-machine collaboration approach enables an accelerated discovery-to-unveiling of promising electrode processes, providing a feasible way to promote game-changing electrochemical technologies.