Modulation of the Structure of the Conjugated Polymer TMP and the Effect of Its Structure on the Catalytic Performance of TMP-TiO2 under Visible Light: Catalyst Preparation, Performance and Mechanism.

The photocatalytic activity of titanium dioxide (TiO2) is largely hindered by its low photoresponse and quantum efficiency. TiO2 modified by conjugated polymers (CPs) is considered a promising approach to enhance the visible light responsiveness of TiO2. In this work, in order to investigate the effect of CP structural changes on the photocatalytic performance of TiO2 under visible light, trimesoyl chloride-melamine polymers (TMPs) with different structural characteristics were created by varying the parameters of the polymerisation process of tricarbonyl chloride (TMC) and melamine (M). The TMPs were subsequently composited with TiO2 to form complex materials (TMP-TiO2) using an in situ hydrothermal technique. The photocatalytic activity of TMP-TiO2 was evaluated by the degradation of rhodamine B (RhB). The results showed that the trend of the structure of the TMP with the reaction conditions was consistent with the visible light responsiveness of TMP-TiO2, and TMP (1:1)-TiO2 had the best photocatalytic activity and could degrade 96.1% of the RhB. In conclusion, our study provided new insights into the influence of the structural changes of TMPs on the photocatalytic activity of TMP-TiO2 under visible light, and it improves our understanding of how conjugated polymers affect the photocatalytic activity of TiO2 under visible light.

Synthesis of vertically aligned CaTiO3 nanotubes with simple hydrothermal method and its photoelectrochemical property.

Perovskite-type oxides have become the hotspots of functional materials due to their various excellent performances. As a typical material with a perovskite structure, CaTiO3 (CTO) possesses a similar band gap to TiO2 with less defects and recombination centers, which makes it a promising alternative material to TiO2. In particular, the CTO nanotube structure has a large specific surface area and unique photochemical and electron-transport properties, and these advantages further expand its application range. In this paper, a highly ordered and vertically aligned CTO nanotube array was successfully synthesized by a simple hydrothermal method with TiO2 nanotube (TNT) arrays as the precursor. It was found that the CTO nanotube had a higher optical absorption ability (3.4 eV), photovoltage (500 mV) and photocurrent density (0.004 A cm-1) under ultraviolet irradiation, compared to the TNT (350 mV and 0.0036 A cm-1). At the same time, the electrochemical impedance spectroscopy, Mott-Schottky and stability tests indicate that the CTO nanotube might be a promising alternative choice as the photoelectric material for a TNT.

Degradation of organic dyes by a new heterogeneous Fenton reagent - Fe2GeS4 nanoparticle.

The heterogeneous Fenton system has become the hotspot in the decontamination field due to its effective degradation performance with a wide pH range. Based on the unstable chemical properties of pyrite, in this article, Fe2GeS4 nanoparticles with better thermodynamic stability were prepared by vacuum sintering and high energy ball milling and its potential as Fenton reagent was investigated for the first time. Three determinants of the heterogeneous Fenton system including the iron source, hydrogen peroxide, pH and the degradation mechanism were investigated. The catalyst dosage of 0.3 g/L, initial H2O2 concentration in the Fenton system of 50 m mol/L and pH of 7 were chosen as the best operational conditions. An almost complete degradation was achieved within 5 min for methylene blue and rhodamine b while 10 min for methyl orange. The total organic carbon removal efficiencies of Fe2GeS4 heterogeneous Fenton system for methylene blue, methyl orange and rhodamine b in 10 min were 56.3%, 66.2% and 74.2%, respectively. It's found that the degradation ability could be attributed to a heterogeneous catalysis occurring at the Fe2GeS4 surface together with a homogeneous catalysis in the aqueous phase by the dissolved iron ions.

Antibacterial abilities and biocompatibilities of Ti-Ag alloys with nanotubular coatings.

PURPOSE: To endow implants with both short- and long-term antibacterial activities without impairing their biocompatibility, novel Ti-Ag alloy substrates with different proportions of Ag (1, 2, and 4 wt% Ag) were generated with nanotubular coverings (TiAg-NT). METHODS: Unlike commercial pure Ti and titania nanotube, the TiAg-NT samples exhibited short-term antibacterial activity against Staphylococcus aureus (S. aureus), as confirmed by scanning electron microscopy and double staining with SYTO 9 and propidium iodide. A film applicator coating assay and a zone of inhibition assay were performed to investigate the long-term antibacterial activities of the samples. The cellular viability and cytotoxicity were evaluated through a Cell Counting Kit-8 assay. Annexin V-FITC/propidium iodide double staining was used to assess the level of MG63 cell apoptosis on each sample. RESULTS: All of the TiAg-NT samples, particularly the nanotube-coated Ti-Ag alloy with 2 wt% Ag (Ti2%Ag-NT), could effectively inhibit bacterial adhesion and kill the majority of adhered S. aureus on the first day of culture. Additionally, the excellent antibacterial abilities exhibited by the TiAg-NT samples were sustained for at least 30 days. Although Ti2%Ag-NT had less biocompatibility than titania nanotube, its performance was satisfactory, as demonstrated by the higher cellular viability and lower cell apoptosis rate obtained with it compared with those achieved with commercial pure Ti. The Ti1%Ag-NT and Ti4%Ag-NT samples did not yield good cell viability. CONCLUSION: This study indicates that the TiAg-NT samples can prevent biofilm formation and maintain their antibacterial ability for at least 1 month. Ti2%Ag-NT exhibited better antibacterial ability and biocompatibility than commercial pure Ti, which could be attributed to the synergistic effect of the presence of Ag (2 wt%) and the morphology of the nanotubes. Ti2%Ag-NT may offer a potential implant material that is capable of preventing implant-related infection.