Urea- and cetyltrimethyl ammonium bromide-assisted hydrothermal synthesis of mesoporous enzyme-like molecularly imprinted TiO₂ nanoparticles with molecular recognitive photocatalytic activity

Using CTAB and urea as structure-directing agents, we synthesized mesoporous enzyme-like molecularly imprinted TiO₂ nanoparticles with molecular recognitive photocatalytic ability by hydrothermal method. Adopting 4-nitrophenol as target pollutant, we found that the adsorption capacity of enzyme-like molecularly imprinted TiO₂ for 4-nitrophenol is about three times that of the corresponding non-imprinted TiO₂ (control TiO2), and the enzyme-like molecularly imprinted TiO₂ shows a relative selectivity coefficient of 3.645. Moreover, the mesoporous enzyme-like molecularly imprinted TiO₂ exhibits molecular recognitive photocatalytic activity for 4-nitrophenol under simulated solar light irradiation. The uniqueness of enzyme-like molecularly imprinted TiO₂ is attributed to the geometric and chemical complementation between the target molecules and "imprinted cavities" of enzyme-like molecularly imprinted TiO₂ nanoparticles. The results indicate that the convergence of molecular imprinting technology and mesoporous structure is powerful basis for the construction of efficient photocatalysts that are highly selective towards a particular organic pollutant.