Search

Metal–organic framework (MOF) materials have been extensively incorporated with inorganic semiconductor photocatalysts to improve their photocatalytic activity through an efficient charge transfer process across their heterointerface. In this work, octahedral UiO-66-NH2 MOFs with edge-lengths of 110–330 nm are uniformly decorated on the surface of TiO2 electrospun nanofibers by a traditional solvothermal method combined with activation pretreatment. Before the solvothermal growth of UiO-66-NH2, the TiO2 electrospun nanofibers were activated in NaOH solution to etch the TiO2 surface for allowing the exposure of lattice oxygen. The exposed lattice oxygen on the TiO2 surface could interact with the MOF precursor of Zr4+ ions, thus enabling octahedral UiO-66-NH2 to grow uniformly on the surface of TiO2 nanofibers with an intimate Ti–O–Zr hetero-interface. Such an intimate hetero-interface provides an effective channel for boosting the electron transfer between UiO-66-NH2 and TiO2 in their heterostructure. Thus, the UiO-66-NH2/TiO2(anatase) heterostructures exhibited enhanced photocatalytic activity for H2 production as compared to either TiO2(anatase) nanofibers or UiO-66-NH2 nanooctahedra in the presence of Rhodamine B (RhB) as a sensitizer under visible light irradiation. In particular, the decoration of UiO-66-NH2 nanooctahedra on anatase/rutile mixed TiO2 nanofibers could induce further enhancement of the photocatalytic H2 production. The enhanced photocatalytic activity is attributed to the multi-step continuous interfacial transfer of photoinduced electrons with the way of RhB → UiO-66-NH2 → TiO2(anatase) → TiO2(rutile). [ABSTRACT FROM AUTHOR]

Abstract: In this work, V-doped TiO2 nanofibers with different V contents have been fabricated by an electrospinning technique. The as-prepared nanofibers were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectra, X-ray photoelectron spectroscopy (XPS), and UV–Vis diffuse reflectance (DR) spectroscopy. The results indicated that the V4+ or V5+ ions were successfully incorporated into the crystal lattice of anatase TiO2 nanofibers. Meanwhile, the V doping could extend the visible light absorption of TiO2 nanofibers. The photocatalytic experiments indicated that the obtained V-doped TiO2 nanofibers possessed high activity for the photodegradation of organic pollutant methylene blue (MB). Especially, the 1.0 and 5.0wt.% V-doped TiO2 nanofibers exhibited the best catalytic activity under visible and ultraviolet (UV) light irradiation, respectively. Also, these nanofibers could be easily recycled without a decrease of the photocatalytic activity. [Copyright &y& Elsevier]

Amine-functionalization of TiO2 nanoparticles, through a solvothermal approach, substantially increases the affinity of CO2 on TiO2 surfaces through chemisorption. This chemisorption allows for more effective activation of CO2 and charge transfer from excited TiO2, and significantly enhances the photocatalytic rate of CO2 reduction into methane and CO. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthesis of 2D g-C 3 N 4 /SnS 2 /TiO 2 ternary photocatalyst was present. • g-C 3 N 4 /SnS 2 /TiO 2 showed broad photoresponsive range and promoted charge separation. • The continuous charge steps were fabricated at the hetero-interface of catalyst. • The photocatalytic disinfection activity of g-C 3 N 4 /SnS 2 /TiO 2 was highly enhanced. • Both O 2 - and h+ are responsible for photocatalytic process of g-C 3 N 4 /SnS 2 /TiO 2. The development of inexpensive and high-efficient semiconductor photocatalysts is of great significance for achieving the goal of environmental remediation. However, the fast recombination of the photoinduced charge-carriers in semiconductor photocatalysts still poses a huge obstacle. In this contribution, we pave "continuous charge steps" in multiple 2D-semiconductor hetero-interface through an orderly assembly of 2D semiconductors of g-C 3 N 4 , SnS 2 , and TiO 2 nanosheets (NSs) by using a facile ultrasonic dispersion and subsequent heat treatment. The matchable energy band structures between the above three 2D NSs allows their orderly composite (g-C 3 N 4 /SnS 2 /TiO 2 NSs) to possess two kinds of broad 2D hetero-interface configurations (g-C 3 N 4 /SnS 2 /TiO 2 and TiO 2 /g-C 3 N 4 /SnS 2) with the extended light-harvesting range. The time-resolved photoluminescence spectroscopy results prove that both of the above hetero-interface configurations could induce the formation of "continuous charge steps" to accelerate the interfacial electron transfer. Thus, upon UV–visible light irradiation, the as-synthesized g-C 3 N 4 /SnS 2 /TiO 2 NSs exhibited 4.2–7.5 fold enhancement for the photocatalytic degradation of Rhodamine B. Notably, the photocatalytic disinfection efficiency of the g-C 3 N 4 /SnS 2 /TiO 2 NSs for Escherichia coli could be over 99.99% after simulated sunlight irradiation for only 30 min. This study opens up a new path for sensible design of ternary heterostructure photocatalyst with continuous charge steps towards an extraordinary photocatalytic activity. [ABSTRACT FROM AUTHOR]

• TiO 2 /Cu 2 O/CuO CNFs is produced via a photoinduced phase-transition on the TiO 2 /CuO CNFs. • The TiO 2 /Cu 2 O/CuO CNFs exhibited the enhanced sensing property for glucose. • The sensitivity of TiO 2 /Cu 2 O/CuO CNFs depends on the TiO 2 content in the CNFs. • The sensing property of TiO 2 /Cu 2 O/CuO CNFs electrode is recoverable via the light irradiation. • The CNFs electrode possesses a good long-term stability, high anti-interference ability, and good reproducibility. The TiO 2 /Cu 2 O/CuO composite nanofibers (CNFs) were obtained via the photoinduced phase-transition process occurring in the electrospun TiO 2 /CuO CNFs. The TiO 2 /Cu 2 O/CuO CNFs electrode showed the higher sensitivity (2074.7 µA·mM−1·cm−2; 0–2 mM) than the pure CuO NFs, TiO 2 NFs, and TiO 2 / CuO CNFs electrodes, respectively. The enhanced glucose sensing performance is attributed to the existence of multiple valence-states and redox-couples in TiO 2 /Cu 2 O/CuO CNFs to promote the redox reaction. [Display omitted] Constructing metal-oxide-based composites with the multiple valence-states and redox-couples has been proved as an effective strategy to enhance the performance of non-enzymatic glucose sensing. Herein, we report a mild and efficient method to prepare multiple-valent copper-based oxide composite nanofibers (Cu x O CNFs) through introducing the TiO 2 photosensitizer into the CuO NFs for actuating the localized phase transition from tenorite CuO (Cu2+) to cuprite Cu 2 O (Cu+) upon UV–visible light irradiation. The sensitivity of the obtained TiO 2 /Cu 2 O/CuO CNFs for glucose sensing (0–2 mM) could be enhanced by 1.12–1.31 times as compared to that of the TiO 2 /CuO CNFs. The enhanced sensitivity is dependent on the TiO 2 -content in the primal TiO 2 /CuO CNFs. When introducing 5.0 at.% of TiO 2 into the CuO nanofibers, the photoinduced phase-transition process could result in the formation of optimal TiO 2 /Cu 2 O/CuO CNFs with the component ratio of Cu 2 O to CuO at 0.46:1. This TiO 2 /Cu 2 O/CuO CNFs (2074.7 µA·mM−1·cm−2; 0.25 µM) exhibited nearly 1.32-fold improvement on the sensitivity and 3.0-fold enhancement on the detection limit as compared to the corresponding values of the pure CuO electrospun nanofibers (1581 µA·mM−1·cm−2; 0.75 µM). After the continuous measurements for 14 days, the sensitivity of the optimal sample could maintain 89.4% of its initial value. Notably, its sensitivity could be further recovered to 97.4% of the initial value after UV–visible light irradiation for 1 h. [ABSTRACT FROM AUTHOR]

• TiO 2 was synthesized by a solvothermal method and treated with N-plasma at atmospheric pressure. • Ti3+ ions of N-TiO 2 form the Ti3+ self-doped system, which causing the light absorption range enhanced. • The catalytic H 2 evolution of N-TiO 2 is 14.85 times higher than that of the pristine TiO 2 NFs. [Display omitted] The N-TiO 2 was prepared by N-plasma treatment at room temperature and ambient, which caused the results of higher generation of oxygen vacancy. The reaction also resulted in reducing more Ti3+, and forming the Ti3+ self-doped system, changing the electronic structure of Ti3+, enhancing its light absorption range, and then enhancing its photocatalytic activity. The photocatalytic activity was ~14.85 times higher than that of the pristine TiO 2. An enhancement of the photocatalytic activity of Titanium dioxide nanosheets (TiO 2 NFs) by N 2 plasma (N-plasma) treatment has been suggested. TiO 2 NFs was synthesized by a solvothermal method and treated with N-plasma at atmospheric pressure. Then the as-prepared TiO 2 and N-plasma treated TiO 2 (N-TiO 2) NFs photocatalyst were extensively characterized. Interestingly, more oxygen vacancy and Ti3+ ions were found in the N-TiO 2 NFs. Meanwhile, Ti3+ ions form the Ti3+ self-doped system, which causing the light absorption range enhanced. The catalytic H 2 evolution of N-TiO 2 NFs at a rate of 8.1 mmol g−1 h−1, which is 14.85 times higher than that of the pristine TiO 2 NFs. These results might suggest new views for the photoactivity of TiO 2 NFs and provide a kind of feasibility for other metal oxides in the photocatalytic field. [ABSTRACT FROM AUTHOR]

Amine-functionalization of TiO2 nanoparticles, through a solvothermal approach, substantially increases the affinity of CO2 on TiO2 surfaces through chemisorption. This chemisorption allows for more effective activation of CO2 and charge transfer from excited TiO2, and significantly enhances the photocatalytic rate of CO2 reduction into methane and CO. [ABSTRACT FROM AUTHOR]