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A molecular imprinted polymer (MIP) thin film for photoelectrochemical (PEC) sensing of lindane molecules was constructed by electropolymerizing o-phenylenediamine ( o-PD) monomer and lindane template molecule on titanium dioxide nanotubes. The resulting PEC sensors were characterized by scanning electron microscopy, ultraviolet (UV)-vis spectra and electrochemical impedance spectra. Clearly, the imprinted film showed high selectivity to lindane in our case. Under visible light irradiation, MIP film can generate the photoelectric transition from the highest occupied molecular orbital to the lowest unoccupied molecular orbital, delivering the excited electrons to the conduction band of titanium dioxide nanotubes. Simultaneously, it is believed that a positive charged hole (h) of MIP that took part in oxidation process was consumed to promote the amplifying photocurrent response. The MIP-based PEC sensor had an excellent specificity and could be successfully applied to the recognition and detection of lindane, indicating a promising application in handling with organochlorine pesticide. [ABSTRACT FROM AUTHOR]

A molecular imprinted polymer thin film for photoelectrochemical (PEC) sensing of chlorpyrifos molecules was first constructed by electropolymerizing the o-phenylenediamine (o-PD) monomer and chlorpyrifos template molecule on gold nanoparticles-modified titanium dioxide nanotubes. The resulting PEC sensors were characterized by scanning electron microscopy, ultraviolet (UV)-vis spectra and electrochemical impedance spectra. Clearly, the imprinted film showed high selectivity to chlorpyrifos in our case. Under visible light irradiation, poly(o-phenylenediamine) (PoPD) can generate the photoelectric transition from the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO), delivering the excited electrons to the AuNPs, and then to the conduction band (CB) of the titanium dioxide nanotubes (TiO2 NTs). Simultaneously, it is believed that a positively charged hole (h+) of PoPD that took part in the oxidation process was consumed to promote the amplification of photocurrent response. Under the optimal experimental conditions, the photocurrents were proportional to the concentrations of chlorpyrifos ranging from 0.05 to 10 μmol L−1 with the detection limit of 0.96 nmol L−1. The PEC sensor had an excellent specificity and could be successfully applied to the detection of reduced chlorpyrifos in green vegetables, indicating a promising application in PEC sensing. [ABSTRACT FROM AUTHOR]

[Display omitted] • E–TiO 2 @rGO with OVs were prepared through crystal defect engineering. • Mixed crystal and OVs enhanced electron-hole pairs separation efficiency. • E–TiO 2 @rGO improved 2,4,6-TCP dichlorination process and degradation efficiency. • The toxicity of 2,4,6-TCP and its intermediates was evaluated via ECOSAR and DFT. Chlorophenolic pollutants pose serious threats to the aquatic ecosystem. Photocatalysis technology has broad prospects for decontamination. In this work, MXene-derived TiO 2 nanocomposites with mixed-crystal characteristics and oxygen vacancies (OVs) (E–TiO 2 @rGO) were successfully synthesized by atmosphere modulation. Compared with commercial TiO 2 and N 2 –TiO 2 @rGO (anatase phase), the rate constants of E–TiO 2 @rGO (0.06874 min−1) over 2,4,6-trichlorophenol (2,4,6-TCP) degradation increased 4 and 1.3 times, respectively. The enhanced photocatalytic performance was attributed to the co-existence of anatase and rutile phases. On the one hand, the mixed-crystal phase narrowed the band gap, broadening the light absorption range. On the other hand, it induced the generation of OVs, which has been demonstrated by DFT calculation. The presence of OVs improved the adsorption and activation of O 2 and H 2 O molecules, beneficial for the formation of active free radicals. In addition, the incorporation of rGO promoted the separation of electron-hole pairs. The Gibbs free energy of 2,4,6-TCP degradation revealed that the OVs and mixed-crystal could reduce the energy barrier of the rate-determining step, thereby boosting the dichlorination efficiency of 2,4,6-TCP. The superoxide free radical (O 2 −) was determined as the dominant active species. Finally, a possible mechanism of 2,4,6-TCP degradation with E–TiO 2 @rGO was clarified clearly. The proposed mixed-crystal defect engineering represents a novel strategy in the design and synthesis of photocatalysts. [ABSTRACT FROM AUTHOR]

Scheme: Adsorption mechanism of TiO2/CS/P(LLA-CL) nanofibers for Cu(II) in aqueous. Herein, titanium dioxide/chitosan/poly(lactide-co-caprolactone) (TiO 2 /CS/P(LLA-CL)) composite membranes with highly efficient adsorption of copper ions (Cu(II)) in aqueous solution were developed, through a facile electrospinning method. First, TiO 2 nanoparticles were ultrasonically dispersed in CS/P(LLA-CL) solution to get a uniform suspension. Afterwards, the mixture was applied for electrospinning to generate the smooth and bead-free composite membranes. The high adsorption capability of the composite membranes on Cu(II) was mainly attributed to the combination of TiO 2 nanoparticles, CS/P(LLA-CL) matrix and nanosized membrane. Among those, the TiO 2 /CS/P(LLA-CL) composite membrane with 2% TiO 2 content demonstrated the maximum adsorption capability (˜190.5 mg g−1) for Cu(II) from aqueous solution. Their adsorption behaviors were well conformed to pseudo-second-order kinetic model and Langmuir isotherm model. Moreover, FTIR and XPS results confirmed the existed chelation and ion exchange between the membrane and the Cu(II) during adsorption process. Due to its simplicity, effectiveness and stability in water, this type of composite membrane may serve as a promising environmentally-friendly and non-toxic adsorbent for removal of Cu(II) in aqueous. [ABSTRACT FROM AUTHOR]

[Display omitted] • C and F co-doped TiO 2 nanosheets were synthesized by pyrolysis of layered MXene. • C-F-TiO 2 was applied to photocatalytic degradation of 2,4,6-TCP. • The doping of C and F increased the generation of active radicals and decreased the band gap. • The recombination rate of photogenerated electron-hole was inhibited. • C-F-TiO 2 nanosheets exhibited remarkable photocatalytic activity. Nonmetal doping is widely used in the modification of titanium dioxides (TiO 2) for photocatalytic applications. As a typical two-dimensional layered nanomaterial, the excellent physical and chemical properties of MXene materials have been the focus of current research. In this study, carbon and fluorine co-doped MXene derived TiO 2 nanosheets (labelled as C-F-TiO 2) were successfully synthesized and used as catalysts for degrading 2,4,6-trichlorophenol (2,4,6-TCP) under UV light irradiation. The C-F-TiO 2 with ultrathin nanosheet structure enhanced light absorption range and decreased the bandgaps. The degradation efficiency of 2,4,6-TCP by C-F-TiO 2 was over 99 % in 90 min, and the degradation rate was more than twice that of commercial TiO 2. The degradation rate still remained about 90 % in 90 min after five cycles. The results of quenching experiments and electron spin resonance (ESR) illustrated that more reactive oxygen species (ROS) were generated in the C-F-TiO 2 /UV system, which was 1.5 times that of commercial pure TiO 2 , and •O 2 – was the dominant ROS for 2,4,6-TCP degradation. This study provided insight to utilize physicochemical characteristics of MXene to synthesize non-metal co-doped TiO 2 nanosheet as a catalyst, exhibiting excellent reactivity in the potential application for organic pollutant degradation. [ABSTRACT FROM AUTHOR]

Abstract: PVDF/TiO2 hybrid microfiltration membranes with different nano-TiO2 dosage were prepared via thermally induced phase separation (TIPS) method, and dimethal-phthalate (DMP) was used as a diluent. The membranes prepared were characterized by scanning electron microscope, transmission electron microscope, X-ray diffractometer, Fourier-transform infrared spectroscopy and differential scanning calorimetry. Their properties such as pure water flux, contact angle, porosity and mechanical performances were also determined. Results showed that PVDF and PVDF/TiO2 hybrid membranes were formed by solid–liquid phase separation and had spherical crystallites structure with cells. The addition of nano-TiO2 particles to the PVDF/DMP mixtures had a strong effect on the crystallization temperature of hybrid membranes and crystallization formation in the TIPS process. The addition of the nano-TiO2 particles did not affect the type of PVDF crystal form (α phase). Nano-TiO2 particles were well distributed in PVDF matrix at the lower concentration and exist in a continuous phase and aggregated in PVDF matrix at the higher concentration. Pure water flux, contact angle, porosity, tensile strength and elongation at break first increased, then decreased with the increase of TiO2 dosage. [Copyright &y& Elsevier]

Oxygen vacancy and template cavity riched TB-TiO 2 @MFA prepared by one-step pollutant template method exhibits excellent selective degradation ability to CIP under visible light irradiation. [Display omitted] • TB-TiO 2 @MFA is obtained by one-step pollutant template method. • One-step pollutant template method endows samples with oxygen vacancy and template cavity. • Template cavities are used to enhance the selectivity and the specific surface area. • Oxygen vacancies are formed to improve the visible light catalytic performance. • TB-TiO 2 @MFA has excellent selective degradation ability to CIP. Currently, the lack of visible light response, small specific surface area, and non-selectivity limit the development of TiO 2. In this paper, the black TiO 2 @MFA with template cavity (TB-TiO 2 @MFA) was synthesized by one-step pollutant template method. The one-step pollutant template method not only endowed the sample with a large number of oxygen vacancies, but also simultaneously endowed the sample with a wealth of template cavities. The existence of oxygen vacancy improved the electron transfer efficiency and visible light absorption ability, the existence of template cavity improved the contact of TB-TiO 2 @MFA with ciprofloxacin (Template pollutant). Hence the existence of oxygen vacancy and template cavity together led to the improvement of the photocatalytic performance of TB-TiO 2 @MFA. The degradation rate of TB-TiO 2 @MFA to ciprofloxacin is 11.5 times that of TiO 2. More importantly, the template cavity endowed the sample with excellent selective degradation ability, the selectivity coefficient of TB-TiO 2 @MFA to TiO 2 @MFA was 2.44, and the selectivity coefficient of TB-TiO 2 to TiO 2 was 2.76. This work had certain reference significance for designing specific functional photocatalytic materials. [ABSTRACT FROM AUTHOR]