A Polymer-Intercalated Modulation Assembly Strategy Towards Mesoporous Single-Crystalline BiVO<sub>4</sub> Materials for Enhanced Photocatalytic Performance.

Abstract

The rapid recombination of photogenerated electron-hole pairs is a bottleneck constraining the improvement of photocatalytic efficiency. The construction of porous single-crystalline BiVO₄ is expected to resolve this issue and provide plenty of active sites for charge carriers to promote the catalytic reaction. However, due to the fact that the synthesis process requires a delicate balance between the kinetic-driven co-assembly process and thermodynamic-driven crystallization process, it faces significant challenges. Herein, a polymer-intercalated modulation assembly strategy is proposed for synthesizing mesoporous single-crystalline BiVO₄ (MSC BiVO₄) with tunable pore structure. In this case, the co-assembly of the two metal precursors, acetate ions and polyethyleneimine (PEI), leads to the formation of an inorganic-organic composite via coordination and hydrogen bonding. Moreover, the "modulator" acetate ions obviously weaken the effect of PEI on the original crystal growth orientation of metal oligomers, thereby maintaining the single-crystalline structure. The dendritic PEI acts as a "porogenic agent" to develop a 3D network to intercalate into metal oligomers and form the mesoporous structure. Various characterizations and theoretical calculations verified that the excellent photocatalytic performance with 99% conversion and 99% selectivity for various aromatic alcohols of the as-prepared MSC-BiVO₄-1800 is attributed to its single-crystalline properties and well-defined mesoporous structure with vanadium vacancy microenvironment.