Preparation of weak-light-driven TiO₂-based catalysts via adsorbed-layer nanoreactor synthesis and enhancement of their photo-degradation performance in seawater

Highlights: • TiO₂ particles with size <10 nm distributed homogeneously on GO surface by ALNS. • TiO₂ crystallization and GO reduction both occurred during solvothermal treatment. • Tight interaction between TiO₂ and GO surface could inhibit particles aggregation. • Strong phenol adsorption on catalyst enhanced photocatalytic activity in seawater. • The structure-activity relationship of catalyst by weak light in seawater were studied. - Abstract: Graphene oxide (GO) was first employed as a support in preparing TiO₂ nanoparticles by adsorbed-layer nanoreactor synthesis (ALNS). Both TiO₂ crystallization and GO reduction simultaneously occurred during solvothermal treatment with alcohol as a solvent. By transmission electron microscopy, high resolution transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and photoluminescence spectroscopy, the results showed that TiO₂ nanoparticles with less than 10 nm of size distributed very homogeneously on the GO surface. Tight interaction between TiO₂ particles and GO surface could effectively inhibit the aggregation of TiO₂ particles, during solvothermal treatment for anatase TiO₂ formation. Alcohol could also reduce oxygenated functional groups on GO surface after solvothermal treatment. TiO₂ particles with small size and the decrease in oxygenated functional groups on the GO surface both caused high separation efficiency of photo-generated charge carriers, thus resulting in high photo-degradation performance of catalysts. Strong phenol adsorption on photocatalyst was key to enhancing photo-degradation efficiency for phenol in seawater. Moreover, the change in catalyst structure was minimal at different temperatures of solvothermal treatment. But, the degradation rate and efficiency for phenol in seawater were obviously enhanced because of the sensitive structure–activity relationship of catalysts under weak-light irradiation.