Morphology-Controlled Synthesis of Peanut-like BiVO4 via Viscosity-Engineered Solvent Systems: Toward Enhanced Photocatalytic Water Remediation

Photocatalytic technology enables effective remediation of aqueous pollutants, owing to its environmental compatibility and efficiency. This research aims to optimize the synthesis pathway for bismuth vanadate (BiVO 4 ), a pivotal photocatalyst, through hydrothermal processing. By modulating the water/ethylene glycol (EG) solvent ratio, we established a high-viscosity system that enables precise control over BiVO 4 nucleation-growth kinetics and crystallographic orientation, generating biomimetic peanut-like hierarchical architectures. The polyol solvent EG, with a viscosity ∼30-fold higher than deionized water and strong coordination capability, critically governs precursor ion behavior. At elevated EG proportions (e.g., H 2 O: EG = 1:2, v/v), the hydroxyl groups of EG molecules preferentially coordinate with Bi 3+ ions to form stable [Bi(EG)_n] 3+ complexes, retarding Bi 3+ release, lowering supersaturation, and shifting nucleation from instantaneous to progressive modes. This transition facilitates uniform primary nanoparticle formation. Integrated characterization employing XRD, UV-DRS, FT-IR, XPS, BET, TEM, and SEM techniques conclusively demonstrated the structural integrity of the synthesized system. The optimized 20EG-BiVO 4 demonstrated exceptional cycling stability (85.4% efficiency retention after 4 cycles) and broad-spectrum degradation capability toward antibiotics and dyes (61.4% enhancement vs. conventional decahedral BiVO 4 ). This acid/base-free synthesis strategy based on EG obviates the necessity for pH regulation, thereby providing simplified processing and reduced costs in developing advanced photocatalytic systems.