A Polymer-Oriented Solvent-Mediated Co-Assembly Strategy to Mesoporous Metal Vanadates for Photocatalytic Degradation

Mesoporous metal vanadates (mMVO) are promising visible-light photocatalysts for energy conversion and environmental remediation owing to their suitable band structures, broad visible-light absorption, and excellent chemical stability. However, the controlled synthesis of crystalline mMVO remains challenging, involving the complicated coassembly process and high-temperature crystallization. Herein, we develop a facile polymer-oriented solvent-mediated coassembly strategy to prepare mMVO without additional chelating agents. Using mesoporous InVO4 (mIVO) as a representative example, the ethanol/water volume ratio is used to tune solvent polarity and thereby regulate the electrostatic coassembly of protonated poly(ethylenimine) (PEI), polyoxovanadate species, and In3+ into compact inorganic-organic composites. Subsequent hydrothermal crystallization and calcination yield mIVO with a well-developed mesoporous framework. This strategy can be extended to synthesize a series of mMVO. Among the obtained samples, mIVO (1/1), synthesized at an ethanol/water volume ratio of 1/1, exhibits excellent visible-light photocatalytic degradation of methylene blue (MB), achieving a degradation efficiency of 97.8% within 40 min under irradiation with λ > 420 nm. Experimental results demonstrate that the enhanced activity originates from the synergistic effects of the accessible mesoporous structure, abundant oxygen vacancies, and efficient separation and transport of photogenerated charge carriers.