A Facile One-Pot Synthesis of Biomimetic Photocatalyst Zn(II)-Porphyrin-Sensitized 3D TiO Hollow Nanoboxes and Synergistically Enhanced Visible-Light Degradation.

A serials of biomimetic photocatalyst zinc(II) meso-tetra(4-carboxyphenyl)porphyrinato (ZnTCP)-sensitized 3D hierarchical TiO hollow nanoboxes (TiO-HNBs) assembled by six ordered nanosheets with dominant {001} facets exposure (ZnTCP@TiO-HNBs) have been successfully synthesized by a facile one-pot solvothermal method via a topological transformation process with TiOF as template. Infrared spectra (IR), UV-vis spectroscopy, and X-ray photoelectron spectroscopy (XPS) confirmed that ZnTCP played a decisive role in constructing 3D hollow nanoboxes through the formation of ester bond combined to TiO-HNBs, which also provided a transferring photo excited electrons bridge to sensitize TiO-HNBs for enhancing visible-light response. Due to the superior sensitization and biomimetic activity of ZnTCP, the photodegradation rate of rhodamine B (RhB) of as-prepared ZnTCP@TiO-HNBs with ZnTCP/TiOF mass ratio of 2% (T-2p) improves 3.6 times compared to that of TiO-HNBs with a degradation yield of 99% for 2 h under simulated sunlight irradiation (> 420 nm). The enhanced photodegradation ability was attributed to synergistic visible photocatalytic mechanism of biomimetic catalyst, which can not only produce hydroxyl radical (•OH) and superoxide radical (•O) coming from the excitation process of ZnTCP sensitized TiO-HNBs, but also generate singlet oxygen (O) that was only provided by biomimetic enzyme porphyrins. Furthermore, the photocatalyst showed good recycling stability and dispersibility after five rounds, ascribed to ZnTCP strong chemical bonding to the support TiO-HNBs. By means of electrochemical cyclic voltammetry analysis, the effect of central zinc ions and parent porphyrin rings on the redox property of biomimetic catalyst was studied.