Synergistic Size and Electronic Engineering of Cr3C2@C(Nx) Nanoparticles Via Arc-Discharge for High-Performance Zn-Air Batteries

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.