Enhancing Oxygen Reduction on Fe Single-Atom Catalysts by Tuning Noncovalent Interactions in Electrode/Electrolyte Interfaces

Highly efficient electrochemical interfaces are significant for the oxygen reduction reaction (ORR). However, previous efforts have been mainly paid to design catalytic sites with high intrinsic activity and neglect the electrode/electrolyte interfaces, especially the noncovalent interactions in the outer Helmholtz plane (OHP). Herein, an Fe–N–C single-atom catalyst is synthesized and acts as the model catalyst to demonstrate the effect of noncovalent interactions on the ORR performance. Two specific molecules of THA+ and TEA+ with different structures and functional groups have been selected to tune the OHP through noncovalent interactions. TEA+ can adjust the OHP, improve the oxygen diffusion coefficient, and increase the double-layer capacitance. Therefore, TEA+ enhances the activity, selectivity, and stability of Fe–N–C single-atom catalysts toward the ORR. This provides a new approach to finding new directions in designing electrochemical interfaces beyond the intrinsic catalytic sites in acidic electrolytes.