Abstract
CeO(2) is a crucial functional material in catalysis and energy applications, whose performance is highly morphology-dependent. Traditional synthesis methods often rely on organic templates or surfactants, which complicate the processes and pose environmental concerns. This study introduces an eco-friendly approach utilizing a methanol-water (MeOH-H(2)O) mixed solvent system combined with NH(4)HCO(3) to achieve controllable synthesis of multi-morphology CeO(2) without surfactants or templates. The effects of different solvent systems (pure H(2)O, pure MeOH, and their mixtures) and NH(4)HCO(3) as an inexpensive regulator on precursor phase behavior and crystallization were systematically investigated. By optimizing the Ce:N molar ratios (1:1 to 1:7) as well as reaction times (0.5 to 36 h), our findings indicate that H(2)O significantly enhances crystallinity (from 40.9% to 61.4% for precursors, reaching 70.3% after calcination) and promotes octahedra formation in the MeOH-H(2)O mixed system, while NH(4)HCO(3) acts as a structure-directing agent to control size (e.g., ~240 nm octahedra at Ce:N = 1:1, up to 375 nm at Ce:N = 1:2) and partially substitutes for high-temperature calcination in improving crystallinity. Variety morphologies, including plates, dendrites, octahedra, and hollow structures, were successfully synthesized. This work elucidates the synergistic mechanism by which solvents and NH(4)HCO(3) influence CeO(2) nucleation and growth, thereby providing an environmentally friendly synthesis route with significant potential applications in catalysis and energy storage.