Synergistic Size and Electronic Engineering of Cr 3 C 2 @C(N x ) Nanoparticles Via Arc‐Discharge for High‐Performance Zn‐Air Batteries

ABSTRACT Developing efficient non‐precious oxygen reduction reaction (ORR) catalysts is essential for advancing zinc‐air batteries (ZABs). This work presents a one‐step synthesis of core‐shell Cr 3 C 2 @C nanoparticles (NPs) via DC arc‐discharge plasma. Precise regulation of cooling dynamics achieves a switch from growth‐dominated to nucleation‐dominated regimes, enabling controlled preparation of nanoparticles with distinct sizes. The liquid‐nitrogen‐cooled Cr 3 C 2 @C ln NPs exhibit smaller size and higher surface area, leading to enhanced ORR performance. Subsequent nitrogen doping at 700 °C produces Cr 3 C 2 @C ln (N x ) catalysts with precisely tuned nitrogen content (0.65–1.24 at.%). The optimized Cr 3 C 2 @C ln (N 1.13 ) demonstrates outstanding ORR activity with a half‐wave potential ( E 1/2 ) of 0.81 V and superior kinetics, surpassing commercial Pt/C. In situ optical emission spectroscopy (OES) monitors the plasma state and electron temperature, providing fundamental insights into nucleation mechanisms. Density functional theory (DFT) calculations reveal that nitrogen doping optimizes the p ‐band center of carbon and significantly reduces the energy barrier of the rate‐determining step (RDS) (*OH desorption). When applied in both liquid and solid‐state flexible zinc‐air batteries (FZABs), the Cr 3 C 2 @C ln (N 1.13 )‐based cathode delivers exceptional performance, achieving high power densities (230.64 and 164.83 mW·cm −2 , respectively) and remarkable cycling stability. This study offers an efficient strategy for designing high‐performance transition metal carbide electrocatalysts through synergistic control of size and electronic structure.