Surface-Nanocurvation-Induced Microenvironment Regulation Capable of Controlling the Activity of Single-Atom Electrocatalysts

Tuning the interfacial microenvironment of single-atom catalysts with defined electronic structures and favorable electric fields is essential to overcome sluggish kinetics and thus boosts electrocatalytic oxygen reduction reaction (ORR) activity. However, the relationship between microenvironment regulation and catalyst properties remains poorly understood. Herein, enriched single-atom Fe−N₄ sites on nano-curved carbon surfaces (cc-Fe) are designed to investigate the influence of the interface microenvironment on catalyst behaviors. Density functional theory calculations, together with in situ spectro-electrochemical experiments, indicate that curving the surface can effectively modulate the adsorbate binding energies on cc-Fe, thereby promoting the protonation of O₂^*. Finite element method simulations demonstrate that surface nanocurvation-induced strong local electrostatic fields can facilitate mass transfer, enhancing the kinetics of the proton-coupled electron transfer process. The designed cc-Fe catalyst exhibits superior ORR activity (E_1/2 = 0.866 V, comparable to commercial Pt/C, E_1/2 = 0.867 V) and outstanding stability (after 50 000 cycles, E_1/2 decreases by only 9 mV), exceeding those of planar Fe−N₄ and Pt/C. When assembled in a Zn–air battery, it also exhibits superior performance over a benchmark Pt/C air cathode. This study clarified the advantageous impacts of microenvironment regulation via curved configurations and paved the way for the development of high-performance electrocatalysts.