fig1

Figure 1. Schematic illustration of the kinetic control strategy for synthesizing FCG precursors. An initially high solute concentration is deliberately provided to drive a burst of homogeneous nucleation, generating abundant nuclei that serve as seeds for subsequent particle growth. As the reaction proceeds, the supersaturation gradually decreases, and the process becomes growth-dominated (heterogeneous deposition on existing nuclei) rather than further nucleation. Meanwhile, the time-programmed evolution of transition-metal (TM) concentrations in the solution continuously modulates the deposited composition, ultimately producing a radially continuous full concentration gradient within individual precursor particles. C_nuc: Nucleation concentration; C_eq: equilibrium concentration; FCG: full concentration gradient.