Covalent triazine‐based frameworks (CTFs) with a graphene‐like layered morphology have been controllably synthesized by the trifluoromethanesulfonic acid‐catalyzed nitrile trimerization reactions at room temperature via selecting different monomers. Platinum nanoparticles are well dispersed in CTF‐T1, which is ascribed to the synergistic effects of the coordination of triazine moieties and the nanoscale confinement effect of CTFs. CTF‐T1 exhibits excellent photocatalytic activity and stability for H2 evolution in the presence of platinum under visible light irradiation (λ ≥ 420 nm). The activity and stability of CTF‐T1 are comparable to those of g‐C3N4. Importantly, as a result of the tailorable electronic and spatial structures of CTFs that can be achieved through the judicial selection of monomers, CTFs not only show great potential as organic semiconductor for photocatalysis but also may provide a molecular‐level understanding of the inherent heterogeneous photocatalysis.
The development of visible‐light‐active photocatalysts is being investigated through various approaches. In this study, C60‐based sensitized photocatalysis that works through the charge transfer (CT) mechanism is proposed and tested as a new approach. By employing the water‐soluble fullerol (C60(OH)x) instead of C60, we demonstrate that the adsorbed fullerol activates TiO2 under visible‐light irradiation through the “surface–complex CT” mechanism, which is largely absent in the C60/TiO2 system. Although fullerene and its derivatives have often been utilized in TiO2‐based photochemical conversion systems as an electron transfer relay, their successful photocatalytic application as a visible‐light sensitizer of TiO2 is not well established. Fullerol/TiO2 exhibits marked visible photocatalytic activity not only for the redox conversion of 4‐chlorophenol, I?, and CrVI, but also for H2 production. The photoelectrode of fullerol/TiO2 also generates an enhanced anodic photocurrent under visible light as compared with the electrodes of bare TiO2 and C60/TiO2, which confirms that the visible‐light‐induced electron transfer from fullerol to TiO2 is particularly enhanced. The surface complexation of fullerol/TiO2 induced a visible absorption band around 400–500 nm, which was extinguished when the adsorption of fullerol was inhibited by fluorination of the surface of TiO2. The transient absorption spectroscopic measurement gave an absorption spectrum ascribed to fullerol radical cations (fullerol.+) the generation of which should be accompanied by the proposed CT. The theoretical calculation regarding the absorption spectra for the (TiO2 cluster+fullerol) model also confirmed the proposed CT, which involves excitation from HOMO (fullerol) to LUMO (TiO2 cluster) as the origin of the visible‐light absorption. 相似文献
The composites comprising Fe-carbon nanotubes (CNTs) on TiO2 were prepared by a modified sol-gel method and characterized by nitrogen adsorption, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and energy dispersive X-ray analysis. The photocatalytic decomposition of rhodamine B (Rh.B) under UV irradiation and air aeration catalyzed by the composites was measured. The photocatalytic activity of TiO2 nanoparticles was significantly enhanced by the large CNT network that facilitated electron transfer between adsorbed Rh.B molecules and the catalyst substrate and the simultaneous occurrence of the photo-Fenton reaction in the presence of Fe particles. A marked acceleration of the decomposition rate was observed with aeration by flowing air aeration due to the formation of the circulatory photo-Fenton system. Chemical oxygen demand of piggery waste was measured at regular intervals to evaluate the mineralization of wastewater. 相似文献
