TiO2 Nanospheres Research Articles

Periodic mesoporous organosilica functionalized hollow TiO2 sphere for selective aerobic oxidation

A promising synthetic method of functionalized titanium dioxide (TiO2) has been proposed in this work which combined photoactive porphyrin-periodic mesoporous organosilica (PMO) with hollow TiO2 nanospheres to achieve a multi-component synergistic system. The prepared composite TiO2@Pro showed photocatalytic activity in aerobic oxidation of sulfide in the aqueous phase under visible light. The high reactivity was attributed to the increased adsorption and diffusion of substrates due to the catalyst’s large specific surface area (337 m2/g), amphiphilicity, wide visible light absorption, and high electron-hole pair separation rate. This strategy provides a new way of designing TiO2-based photocatalysts for heterogeneous catalysis under visible light.

Mie-Resonant Rutile TiO2 Nanospheres for Unclonable Structural Colors

Monodisperse carbon-embedded rutile TiO2 nanospheres were synthesized through the sol–gel reaction of titanium alkoxide in concert with dodecylamine and the subsequent thermal annealing process in inert gas. Since dodecylamine was uniformly carbonized in nanospheres, the growth of rutile crystals was limited to ∼50 nm in the thermal annealing process, which enabled us to keep the spherical shape of nanospheres. Due to the size and shape uniformity, colloidal films of these rutile TiO2 nanospheres showed unique Mie-resonant structural colors, in which multiple scattering was suppressed due to carbon embedded in nanospheres. Due to the high refractive index of rutile TiO2, there were multiple backscattering peaks in the visible region, which make it extremely difficult to replicate the colorimetric information when they were utilized as encryption inks. Finally, we demonstrated that IR-reflective carbon-embedded rutile TiO2 nanospheres can be used as automotive paints, which can be distinguishable at night for light detection and ranging (LiDAR) systems.

Enhanced photocatalytic water splitting hydrogen production on TiO2 nanospheres: A theoretical- experimental approach

Nowadays emerge a need to obtain materials highly photoactive for different applications such as optoelectronics, contaminant removal or energy production, all of them are priority need to reach sustainable development. Nevertheless, this depends of several factors such as the synthesis method choice can affect the form and structure of final samples. In this report, we present the TiO2 synthesis in anatase phase at 400 °C with different morphologies due to interrelation between acid used during the synthesis and some kinds of glycinates generated. The probable mechanisms for formation of TiO2 nanoparticles and morphology control are discussed. The correspond characterization by means of Scanning Electron Microscopy and Transmission Electron Microscopy, XRD, superficial area reveals that physiochemical properties obtained improve the photocatalytic water splitting hydrogen production. The samples show best photoactivity when these adopt spherical morphology because of a change of electronic densities. On the other hand, DFT calculations were carried out on (TiO2)n n = 15–20 clusters to evaluate the water adsorption and to verify that systems with best symmetry are favored over irregular structures as well as to give a weakening tendency on O − H bonds of waters molecules attached to these semiconductor nanoparticles.

Study on the design and photocatalytic performance of TiO2@g–C3N4–Ag/Ag2O ternary heterojunction nanomaterials

In this work, we designed and prepared the TiO2@g–C3N4–Ag/Ag2O (TCNA) ternary nanoparticle materials in a simple and low-cost hydrothermal method, in which, small Ag/Ag2O nanoparticles were uniformly distributed on a layer of thin g-C3N4 nanosheets coated TiO2 nanospheres. By carefully changing the ratios of surface distributed Ag/Ag2O nanoparticles, the photocatalytic degradation performance of the prepared TCNA can be easily changed. Under the modified catalytic device, we found that a high degradation rate of about 99% at 90 min in degrading RhB can be obtained by TCNA-2 reached, which is 4.7 and 3.6 times higher than the photodegradation rate constants of pure TiO2 and TiO2@g-C3N4 composites, respectively. Furthermore, the prepared TCNA nanomaterials also showed high photocatalytic stability and good cycling properties. The scavengers study indicated that the ·O2− and ·OH were the main active groups of the obtained ternary photocatalysts. Subsequently, we proposed a suitable mechanism for exposing the high photocatalytic performance of our TCNA ternary nanomaterials, which may have a positive influence on the design and preparation of other high-performance ternary photocatalytic nanomaterials.

Branched core-shell a-TiO2@N-TiO2 nanospheres with gradient-doped N for highly efficient photocatalytic applications

A branched core-shell nanosphere composed of an anatase TiO2 (a-TiO2) core and a TiO2 nanobranch shell with gradient-doped N (a-TiO2@N-TiO2) is synthesized by a simple in situ doping method, in which mixed crystal anatase-rutile TiO2 (ar-TiO2) nanosphere is first prepared by oxidizing Ti using H2O2, and then is etched by NH3·H2O to form (NH4)2TiO3 nanobranches, which is converted into a-TiO2@N-TiO2 following an ambient annealing process. The diameter of a-TiO2 core is ∼500 nm, and the thickness of N-TiO2 branched shell is ∼100 nm with gradually increased N concentration from the bottom to the edge. Ultra-thin amorphous coating layers on the branches are also observed. The morphology of the composites could be further tuned by the amount of NH3·H2O, and its effect on the photocatalytic performance is also investigated. The optimized a-TiO2@N-TiO2 shows an outstanding hydrogen evolution rate of 308.1 µmol g−1 h−1 under air mass (AM) 1.5 illumination, and also exhibits highly active in photocatalytic degradation of various refractory organic pollutants, including organic dyes, phenols, antibiotics, and personal care products, with removal ratios higher than 96% after 2 h operation. This can be due to the gradient-doped N-TiO2 nanobranches, which not only provide bending band structure and defect level derived from the N impurities and O vacancies, resulting the formation of n-n+ heterojunctions to improve the charge separation, but also enhance the charge transfer at the liquid-solid interface due to the numerous nanobranches and amorphous coating layers.

High-efficiency graphene oxide membranes intercalated by hollow TiO2 nanospheres and CNS@LDH composite spheres for enhancing dye separation from wastewater

Textile wastewater pollution with dyes has become a major source of water pollution. In the study, GO and composite nanospheres (CNS@LDH and HOTiO2) were used to form the composite materials by electrostatic self-assembly method, and the composite materials vacuum filtration on the surface of CA membrane to prepare the composite membranes for dyes separation. Among them, GO was used as a vertical separation layer in dyes separation, while the hollow structure of HOTiO2 nanosphere with a large specific surface area provided more adsorption sites, and the CNS@LDH nanosphere with core–shell structure played the role of expanding GO sheets and preventing HOTiO2 from collapsing. Compared with the GO membrane, the water flux of three dyes produced by GO/HOTiO2/CNS@LDH composite membrane increased by 18 times with a rejection rate of 99%. In addition, after 10 cycles of experiments, GO/HOTiO2/CNS@LDH composite membrane retained a rejection rate of over 98% with the flux of 79 L∙m−2∙h−1∙bar−1 for MB. GO/HOTiO2/CNS@LDH composite membrane retained a stable rejection rate on three dyes under extreme pH and ionic strength conditions. The composite membrane combined the adsorption and isolation effects of GO, HOTiO2, and CNS@LDH, which significantly enhanced the separation performance of dye wastewater. Accordingly, the GO/HOTiO2/CNS@LDH composite membrane has great potential in practical wastewater treatment.

Fabrication of C-Doped TiO<sub>2</sub> Nanosphere for BTEX Degradation of Paint Thinners with Visible Light Irradiation

Carbon (C)-doped TiO2 nanospheres were produced using a solvothermal method, and then characterised with transmission electron microscopy, powder X-ray diffraction pattern and X-ray photoelectron spectroscopy. The C was doped into the TiO2 nanosphere as planned, and the photocatalytic oxidations were studied in environmental chambers under simulative conditions. C-doped TiO2 nanospheres' photocatalytic performance was evaluated by removing benzene, toluene, ethylbenzene, xylenes (BTEX) of paint thinners via the illumination of visible light. A degradation ratio of 93.4% in 90 min exhibited high photocatalytic activity.

An effective Ni/C co-catalyst for promoting photocatalytic hydrogen evolution over TiO2 nanospheres

Ni/C/TiO2 nanocomposites have been prepared by base-catalyzed hydrolysis of tetrabutyl titanate in the Ni/C suspension and subsequent heat treatment at different temperatures. The Ni/C co-catalyst was fabricated by salt-templated pyrolysis of a nickel oleate complex. Phase and morphological analyses revealed that the Ni/C/TiO2 nanocomposites were largely composed of anatase TiO2 nanospheres. Hydrogen evolution measurements showed that the photocatalytic activity of TiO2 nanospheres was improved by the Ni/C co-catalyst under simulated sunlight. The best-performing Ni/C/TiO2-T700 achieved a H2 evolution rate of 1745.0 μmol h-1 g-1, which was 9-fold as high as pure TiO2 (185.0 μmol h-1 g-1). Based on optical, electrochemical, and photo-electrochemical results, the enhanced catalytic activity could be attributed to the Ni/C co-catalyst promoting the photo-generated charge separation and suppressing the electron-hole pair recombination. This work provides an alternative type of Ni-based co-catalyst for enhancing the hydrogen evolution activity of TiO2-based photocatalysts.

Catalytic effect of highly dispersed ultrafine Ru nanoparticles on a TiO2-Ti3C2 support: Hydrolysis of sodium borohydride for H2 generation

To improve the utilization rate of the precious metal, ruthenium, TiO2 nanospheres containing oxygen vacancies are grown on the surface of layered Ti3C2, and superfine Ru nanoparticles are fixed on the surface of TiO2 nanospheres via hydrogen reduction of a Ru precursor. The presence of titanium in a low oxidation state is verified by X-ray photoelectron spectroscopy, thus confirming the existence of oxygen vacancies. Spherical aberration transmission electron microscopy studies indicate the dispersion of uniform Ru nanoparticles (average diameter: ~2 nm) on TiO2, and the existence of a part of Ru in the form of single atoms. The catalyst with 0.33 wt% Ru loading exhibits the best catalytic performance in the hydrolysis of NaBH4 (NaBH4 hydrolysis rate at 303 K is 60 L·min−1·gRu−1). Further, the catalyst performs well even after five cycles of use.

Improvement of Heat Transfer Properties through TiO2 Nanosphere Monolayer Embedded Polymers as Thermal Interface Materials

A thermal interface material (TIM) is a substance that reduces the thermal resistance between a heat source and heat sink, which facilitates heat conduction towards the outside. In this study, a TiO2 nanosphere (NS)-filler based TIM was fabricated via facile processes such as spin-coating and icing methods. Thermal conductivity of the fabricated TiO2 NS-based TIM was enhanced by increasing the loading contents of the TiO2 NS-filler and successfully cooling down the GPU chipset temperature from 62 °C to 50 °C. Moreover, the TIM with the TiO2 NS-monolayer additionally lowered the GPU temperature by 1–7 °C. The COMSOL simulation results show that the TiO2 NS-monolayer, which was in contact with the heat source, boosts the heat transfer characteristics from the heat source toward the inside of the TIM. The suggested metal oxide monolayer-based TIM is an effective structure that reduces the temperature of the device without an additional filler loading, and it is expected to have a wide range of applications for the thermal management of advanced devices.

Enhanced sensing performance of Au-decorated TiO2 nanospheres with hollow structure for formaldehyde detection at room temperature

Au-decorated hollow TiO2 nanospheres were synthesized via a template method subsequently followed by the reduction of Au nanoparticles decorated on the surface of TiO2. The diameter of the hollow TiO2 nanospheres is 150–200 nm and the thickness of the shell layer is 10–15 nm. The particle size of Au nanoparticles on the surface of TiO2 nanospheres is about 15 nm. The 1 mol% Au-decorated hollow TiO2 nanospheres based chemiresistive-type sensor exhibited a much improved sensing performance to formaldehyde under Ultraviolet (UV) irradiation at room temperature. The response of the sensor to 5 ppm formaldehyde is about 8.5, which is three times higher than that of the pure hollow TiO2 nanospheres based one. The response and recovery time of the sensor to 5 ppm formaldehyde is 36 s and 110 s, respectively. The mechanisms of both electronic and chemical sensitizations induced by Au nanoparticles and the hollow structure were proposed for the enhanced sensing properties.

Photoelectrochemical aptasensor driven by visible-light based on BiFeO3@TiO2 heterostructure for microcystin-LR detection

Herein, a simple and effective visible-light driven photoelectrochemical (PEC) aptasensor was designed using BiFeO3@TiO2 nanocomposites for accurate and rapid detection of microcystin-LR (MC-LR). This composite was obtained by coupling p-type BiFeO3 nanoparticles with n-type TiO2 nanosphere to constructed a p-n heterojunction. This p-n heterojunction not only could narrow the band-gap of TiO2 from 3.14 eV down to 2.14 eV of BiFeO3@TiO2, resulting in superior utilization of visible light. More importantly, it also could accelerate charge separation/transfer leading to enhanced photoelectrochemical (PEC) performance of BiFeO3@TiO2. Based on these excellent optoelectronic performances of BiFeO3@TiO2 composite, a PEC aptasensor with “turning on” signal mechanism was constructed by aminated aptamer as a biorecognition probe. The constructed PEC aptasensor performed gratifying analytical property toward MC-LR with a low detection limit of 0.016 pM (S/N = 3) and a wide detection range (5.0 × 10−5 ∼ 2.5 × 102 nM). This PEC aptasensor possessed promising potential application value for its precise selective and ultrasensitive for MC-LR in practical analysis.

Gold-TiO2@gallic acid nanospheres for enhanced surface-assisted laser desorption/ionization mass spectrometry imaging

Surface-assisted laser desorption/ionization (SALDI) mass spectrometry imaging (MSI) can effectively reduce the matrix interference and ion suppression that occurred in traditional matrix-assisted laser desorption/ionization (MALDI) MSI. In this work, gold nanoparticles (AuNPs) modified TiO2 nanospheres were synthesized and modified with gallic acid (GA) to fabricate Au-TiO2@GA nanospheres (Au-TiO2@GA NSs). The SALDI substrate was prepared by coating the ITO glass slide with Au-TiO2@GA NSs using a gas-assisted electric sprayer. Compared with often-used MALDI matrices such as 2,5-dihydroxybenzoic acid (DHB), 2-mercaptobenzothiazole (MBT), 1,5-diaminonaphthalene (DAN), 2,5-dihydroxyacetophenone (DHA), and 9-aminoacridine (9-AA), the Au-TiO2@GA NSs provide higher detection sensitivity, lower background interference, dual-polarity detection and enhanced ionization efficiency of various endogenous molecules, particularly to the detection of neutral lipids. SALDI MSI could be straightforwardly performed on biological tissues thaw-mounted on the prepared substrate. The spatial distribution of various molecular species was unraveled in the mouse brain, kidney, and liver tissues. Not limited to animal tissues, Au-TiO2@GA NSs showed a more universal application to SALDI MSI of secondary metabolites in plant tissues. The spatial distribution of various natural products was mapped using SALDI MSI, such as parishins in Gastrodia elata tuber (Tianma) and glycoalkaloids in potato tuber. This work provides a high-efficient and high-compatible nanomaterial for SALDI MSI

High-Efficiency Graphene Oxide Membranes Intercalated by Hollow Tio2 Nanospheres and Cns@Ldh Composite Spheres for Enhancing Dye Separation from Wastewater

High-Efficiency Graphene Oxide Membranes Intercalated by Hollow Tio2 Nanospheres and Cns@Ldh Composite Spheres for Enhancing Dye Separation from Wastewater

Enhanced Sensing Performance of Au-Decorated Tio2 Nanospheres with Hollow Structure for Formaldehyde Detection at Room Temperature

Enhanced Sensing Performance of Au-Decorated Tio2 Nanospheres with Hollow Structure for Formaldehyde Detection at Room Temperature

Controllable Synthesis of CE Doped ZnO:TiO2 Nanospheres for Photocatalytic Degradation of MB Dye and Levofloxacin Under Sunlight Light Irradiation

Controllable Synthesis of CE Doped ZnO:TiO2 Nanospheres for Photocatalytic Degradation of MB Dye and Levofloxacin Under Sunlight Light Irradiation

A Cascade Nanozyme with Amplified Sonodynamic Therapeutic Effects through Comodulation of Hypoxia and Immunosuppression against Cancer.

The tumor microenvironment (TME) featured by immunosuppression and hypoxia is pivotal to cancer deterioration and metastasis. Thus, regulating the TME to improve cancer cell ablation efficiency has received extensive interest in oncotherapy. However, to reverse the immunosuppression and alleviate hypoxia simultaneously in the TME are major challenges for effective cancer therapy. Herein, a multifunctional platform based on Au nanoparticles and a carbon dots modified hollow black TiO2 nanosphere (HABT-C) with intrinsic cascade enzyme mimetic activities is prepared for reversing immunosuppression and alleviating hypoxia in the TME. The HABT-C NPs possess triple-enzyme mimetic activity to act as self-cascade nanozymes, which produce sufficient oxygen to alleviate hypoxia and generate abundant ROS. The theoretical analysis demonstrates that black TiO2 facilitates absorption of H2O and O2, separation of electron-holes, and generation of ROS, consequently amplifying the sonodynamic therapy (SDT) efficiency. Specifically, HABT-C exhibits favorable inhibition of immunosuppressive mediator expression, along with infiltrating of immune effector cells into the TME and reversing the immunosuppression in the TME. As a result, HABT-C can effectively kill tumor cells via eliciting immune infiltration, alleviating hypoxia, and improving SDT efficiency. This cascade nanozyme-based platform (HABT-C@HA) will provide a strategy for highly efficient SDT against cancer by modulation of hypoxia and immunosuppression in the TME.

Environmentally-friendly harvesting TiO2 nanospheres and V2O5 microrods from spent selective catalytic reduction catalysts

Spent selective catalytic reduction (SCR) catalysts are defined as hazardous wastes because of the toxicity of V2O5 to the ecological environment. Recycling of V2O5 and TiO2 from the spent SCR catalysts has strikingly social and environmental benefits as well as economic values. In this work, a “NaOH ​+ ​Na2CO3” system was employed to recycle 99.2% of anatase/rutile TiO2 nanospheres with a nanospherical morphology from the spent SCR catalysts by a simple sintering-leaching process. The observed photocatalytic performance of anatase/rutile TiO2 nanospheres was higher than that of the other TiO2 recovered from the spent SCR catalysts, commercial TiO2, and chemosynthetic TiO2, which can be ascribed to the enhanced separation of photo-excited electron/hole in a direct Z-scheme of anatase/rutile TiO2 homostructures. Additionally, high-purity V2O5 microrods with high H2S removal performance were efficiently prepared by a hydrothermal method in the leaching solution, which is superior to the traditional method including NH4VO3 precipitation and solvent extraction as the present method can recycle vanadate from low-grade filtrate with a 99.6% of recovery rate. This study develops an alternative method for controlling pollution of vanadate to soil and water and recycling of valuable metals.

Design of rutile nanospheres decorated rGO/β-CD nanoflakes composite: A sustainable electrocatalyst for effective non-enzymatic determination of L-Tyrosine

A novel and facile electrochemical sensing device has fabricated based on TiO2@rGO/β-CD nanocomposite altered GCE for trace-level detection of L-Tyrosine. The crystalline nature, functional groups, shape morphology of nanocomposite were confirmed using various characterization techniques. The FE-SEM results expose TiO2 nanospheres were strongly bind with flake-like rGO/β-CD composite. The layer-like morphology of GO was modified to a flake-like structure with reduction in occurrence of dextrin linkages attached to GO layers with host-guest supramolecular interaction. These features further confirmed using HR-TEM analysis. The TiO2 nanospheres exist in flake-like surface of rGO/β-CD composite that significantly enhanced the active superficial area, conductivity of nanocomposite. The fabricated electrode shows superior and improved electrocatalytic oxidation, high sensitivity and low detection limits towards L-Tyr. It was ascribed to synergistic recombination between the edge planes of carbon-based materials and TiO2 exist in nanocomposite. The TiO2@rGO/β-CD modified GCE response over wide dynamic range (0.01–1920 μM), LOD (7.6 nM) for L-Tyr detection. Additionally, it displayed notable repeatability, reproducibility and storage stability. Moreover, the practicability of the proposed sensor in Apple juice, Tyr tablet and recovery results satisfactory. All strategies proposed TiO2@rGO/β-CD nanocomposite as sustainable electrocatalyst that could be explored as excellent candidate for detecting the L-Tyrosine in real sample analysis.

Photocatalytic oxidation of ceftiofur sodium under UV–visible irradiation using plasmonic porous Ag-TiO2 nanospheres

In this study, 250 nm sized porous anatase TiO2 nanospheres (TiO2 NSPs) composed of ∼ 10 nm sized anatase TiO2 nanoparticles are obtained through a green synthetic route and their surfaces have been decorated with 3–4 nm sized plasmonic silver nanoparticles (AgNPs). Photoluminescence studies confirm that the AgNPs presence on TiO2 NSPs surface effectively inhibits the radiative charge recombination and thus facilitates charge separation process at the Ag-TiO2 NSPs interface, causing an enhanced photocatalytic activity. About 92% of the ceftiofur sodium (CFS) antibiotic taken initially is oxidized by Ag-TiO2 NSPs upon 90 min white light irradiation, while Ag loaded Degussa P25 TiO2 nanoparticles effects only 71% CFS oxidation. The synergistic effect given by plasmonic AgNPs and the continuous framework of anatase TiO2 NPs contributes to inhibit the electron-hole recombination in the Ag-TiO2 NSPs. Oxidation products of CFS in different water sources and their eco-toxicity effects identified through LC-MS and microtox-bioassays, respectively, indicate that the obtained oxidation products are non-toxic compared to pure CFS. Therefore, porous Ag-TiO2 NSPs could be successfully applied in photocatalytic oxidation technologies, exploiting sunlight for the effective removal of pharmaceutical pollutants from wastewater.