Commercial TiO2 Research Articles

Bioinspired Strategy for Efficient TiO2/Au/CdS Photocatalysts Based On Mesocrystal Superstructures in Biominerals and Charge-Transfer Pathway in Natural Photosynthesis.

Natural photosynthesis involves an efficient charge-transfer pathway through exquisitely arranged photosystems and electron transport intermediates, which separate photogenerated carriers to realize high quantum efficiency. It inspires a rational design construction of artificial photosynthesis systems and the architectures of semiconductors are essential to achieve optimal performance. Of note, biomineralization processes could form various mesocrystals with well-ordered superstructures for unique optical applications. Inspired by both natural photosynthesis and biomineralization, we construct a ternary superstructure-based mesocrystal TiO2 (meso-TiO2)/Au/CdS artificial photosynthesis system by a green photo-assisted method. The well-ordered superstructure of meso-TiO2 and efficient charge-transfer pathway among the three components are crucial for retarding charge recombination. As a result, the meso-TiO2/Au/CdS photocatalyst displays enhanced visible light-driven photocatalytic hydrogen evolution (4.60 mmol h-1 g-1), which is 3.2 times higher than that of commercial TiO2 (P25)/Au/CdS with disordered TiO2 nanocrystal aggregates (1.41 mmol h-1 g-1). This work provides a promising bioinspired design strategy for photocatalysts with an improved solar conversion efficiency.

Enhancement of photocatalytic activity by Z-scheme heterojunction of CaTiO3 nanocuboids and P25

Photocatalysis is an interesting approach to convert solar energy into chemical energy. To achieve efficient energy conversion, a mixed photocatalyst of CaTiO3 nanocuboids and commercial anatase TiO2 nanoparticles P25 were used. This is due to the formation of a heterostructure between CaTiO3 nanocuboids and P25, which enhances the photocatalytic activity. Experiments on the degradation of methylene blue under black light irradiation showed that the hybrid photocatalyst exhibited 11 % higher degradation performance than P25 only. Moreover, a photocatalyst film was formed on FTO glass and used as an electrode for a photoelectrochemical cell (PEC). This is the first time CaTiO3 nanocuboids were mixed with P25 and used as electrodes of PECs.

Synthesis of uniformly dispersed Fe2TiO5 nanodisks: a sensitive photoelectrochemical sensor for glucose monitoring in human blood serum.

A novel photoelectrochemical (PEC) sensor was constructed, using Fe2TiO5 nanodisks under visible-light irradiation, for the determination of glucose in human blood serum. The uniformly dispersed Fe2TiO5 nanodisks were synthesized for the first time by an ion exchange method and subsequent heat treatment. As excellent catalysts, the Fe2TiO5 nanodisks can directly catalyze the oxidation of glucose to produce current in the absence of glucose oxidase. Compared with commercial TiO2, the Fe2TiO5 nanodisks exhibit better activity in the electrocatalytic oxidation of glucose and can generate a photocurrent as a signal for glucose detection. The PEC sensor shows a wide linear range (4 μM-10 mM), a low limit of detection (0.588 μM) and a super sensitivity of 2653 μA mM-1 cm-2, which are much better than similar configurations reported previously. This PEC sensor has been successfully used to monitor glucose in human blood serum. Moreover, this PEC glucose sensor based on Fe2TiO5 nanodisks possesses great potential for application in point-of-care clinical diagnosis.

Preparation of modified TiO2 and its photocatalytic properties

In this chapter, tetrabutyl titanate was used as the titanium source, and the photocatalytic performance of commercial TiO₂ and self-made TiO₂ was compared by sol-gel method. Since ready-made commercial TiO₂ is not easy to be doped and modified, this chapter also performs alkali solution surface modification at the same time as self-made TiO₂ (that is, the TiO₂ to be modified is immersed in alkali solution at different pH values and then dried), and the photocatalytic performance of the two before and after the surface modification of alkali solution is compared. In order to improve the photocatalytic performance of self-made TiO₂, this chapter modifies the iron doping of self-made TiO₂ during the preparation process to enhance its photocatalytic performance. After iron doping modification of TiO₂, in order to further improve its performance, the modified sample was modified with alkali solution surface. In this paper, the microscopic characterization and nitrogen and oxygen catalytic performance tests of each sample were carried out, and the results showed that the photocatalytic performance of self-prepared TiO₂ was significantly better than that of commercial TiO₂. Among the TiO₂ modified by different pH solutions, the catalytic performance was the best at pH 11.5, and the photocatalytic performance of Fe-doped TiO₂ was also improved to varying degrees compared with pure TiO₂, among which Fe doping 0.5% contributed the most to the photocatalytic performance. After the surface modification of Fe (0.5%)-TiO₂ with the best doping amount by alkali solution, the photocatalytic performance was also improved.

Photocatalytic hydrogen production using bimetallic and trimetallic hydrotalcite as photocatalysts

• Bimetallic and trimetallic hydrotalcites were synthesized by coprecipitation method. • The formation of 2D structure characteristic of this type of material was observed. • The chemical composition was determined by XPS and FTIR analysis. • A difference in the positions of VB and CB was observed between both hydrotalcites. • Both hydrotalcites presented a higher production of H 2 than TiO 2. Bimetallic ZnAl and trimetallic ZnCuAl hydrotalcites were synthesized using the coprecipitation method. The presence of the characteristic peaks of layered double hydroxide phases was observed by XRD analysis, as well as the typical like flower morphology of these materials by FESEM and HRTEM analysis. Changes in the valence and conduction bands position, as well as in the band gap calculated by UV-vis spectroscopy and XPS techniques was noted by the presence of Cu in the material. In the photocatalytic behavior for H 2 production in presence of UV irradiation, ZnCuAl hydrotalcite showed the highest yield of H 2 in comparison to ZnAl material, being both photocatalysts more actives that the reference photocatalyst, consisting in commercial TiO 2 (Degussa P-25).

Design and synthesis of anisotropic crystals with π-conjugated rings toward giant birefringence

In this review, aiming to better judge the integrated properties of optical crystals, we came up with the birefringent quality factor and summarized our recent findings on the birefringent crystals similar to α-BaB2O4.

Improved visible light triggered photocatalytic activities of BiOCl photocatalysts via a synergistic effect of doping and heterojunction engineering.

To manipulate the photocatalytic activities of BiOCl photocatalysts, doping and heterojunction engineering are simultaneously adopted. Herein, the photocatalysts Sm3+-doped BiOCl and BiOCl:Sm3+@yg-C3N4 were designed, in which their phase structure, morphology, optical properties and photocatalytic activities were systematically discussed. Excited at 408 nm, red emissions are seen from Sm3+-doped BiOCl microplates and their intensities were impacted by doping content, reaching the maximum value when the Sm3+ content was 1 mol% and the involved concentration mechanism was dominated by quadrupole-quadrupole interaction. Through analyzing the degradation of TC, the visible light triggered photocatalytic behaviors of the resultant compounds were studied. Compared with BiOCl microplates, an improved TC removal ability was seen in Sm3+-doped BiOCl microplates and the products with a Sm3+ content of 0.5 mol% show the best performance. Moreover, through constructing the heterojunction with g-C3N4, the TC removal capacity was further enhanced and the BiOCl:Sm3+@60%g-C3N4 exhibits the optimal photocatalytic activity, which was also much better than that of the commercial SnO2 and TiO2. Accordingly, the ˙O2-, h+ and ˙OH active species were proven to contribute to the involved visible light driven photocatalytic mechanism. Furthermore, the separation and recombination of photogenerated carries via the Z-scheme transfer process in the designed heterojunction composites, led to splendid photocatalytic properties. Additionally, it was verified that the TC solution treated with synthesized compounds was nontoxic toward plant growth. Our findings may propose an available route to regulate the photocatalytic performance of the visible light driven photocatalysts.

TiO2-NGQD composite photocatalysts with switchable photocurrent response.

A series of titanium dioxide-nitrogen doped graphene quantum dot (TiO2-NGQD) composite photocatalysts were synthesized through a simple hydrothermal reaction with varied NGQD content. Through a proposed Z-Scheme heterojunction, the composites were able to achieve increased photocurrent generation and photocatalytic degradation of phenol under both full spectrum and visible only illumination. The prepared composites were able to switch from anodic to cathodic photocurrent by changing the light source from full spectrum to visible wavelengths. The photocatalytic capabilities of the composites were tested by degrading phenol and this was monitored via nuclear magnetic resonance. All composites outperformed the commercial standard P25 TiO2 under both full spectrum and visible irradiation, with the 8 wt% NGQD composite showing a visible improvement of over 600% compared to P25. With the ability to manipulate the generation of majority charge carriers, TiO2-NGQDs have significant potential not only in photocatalysis, but in far reaching applications such as energy harvesting and water splitting.

Highly selective CO2 photoreduction to CO on MOF-derived TiO2.

Metal-Organic Framework (MOF)-derived TiO2, synthesised through the calcination of MIL-125-NH2, is investigated for its potential as a CO2 photoreduction catalyst. The effect of the reaction parameters: irradiance, temperature and partial pressure of water was investigated. Using a two-level design of experiments, we were able to evaluate the influence of each parameter and their potential interactions on the reaction products, specifically the production of CO and CH4. It was found that, for the explored range, the only statistically significant parameter is temperature, with an increase in temperature being correlated to enhanced production of both CO and CH4. Over the range of experimental settings explored, the MOF-derived TiO2 displays high selectivity towards CO (98%), with only a small amount of CH4 (2%) being produced. This is notable when compared to other state-of-the-art TiO2 based CO2 photoreduction catalysts, which often showcase lower selectivity. The MOF-derived TiO2 was found to have a peak production rate of 8.9 × 10-4 μmol cm-2 h-1 (2.6 μmol g-1 h-1) and 2.6 × 10-5 μmol cm-2 h-1 (0.10 μmol g-1 h-1) for CO and CH4, respectively. A comparison is made to commercial TiO2, P25 (Degussa), which was shown to have a similar activity towards CO production, 3.4 × 10-3 μmol cm-2 h-1 (5.9 μmol g-1 h-1), but a lower selectivity preference for CO (3 : 1 CH4 : CO) than the MOF-derived TiO2 material developed here. This paper showcases the potential for MIL-125-NH2 derived TiO2 to be further developed as a highly selective CO2 photoreduction catalyst for CO production.

Hydrothermal synthesis of mesoporous TiO2 nanoparticles for enhanced photocatalytic degradation of organic dye

In this work, mesoporous TiO2 nanoparticle photocatalyst has been prepared by hydrothermal method using titanium tetrachloride as precursor. The resulting photocatalysts have been characterized using X-ray diffraction (XRD), nitrogen adsorption-desorption analyses, RAMAN spectroscopy, Transmission Electron Microscopy (TEM) and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). The results showed that the synthesized 2 OiT was anatase phase and mesoporous with specific surface 133.45 m2/g. The decomposition of methylene blue dye under the influence of ultraviolet light was used to test the photocatalytic performance of the produced TiO2 photocatalyst. The photocatalytic activity of the TiO2 photocatalyst for the breakdown of methylene blue dye was significantly higher than that of the commercial TiO2 P25 used as a reference. Moreover, the prepared photocatalyst was stable and reusable. The larger surface area of hydrothermally produced TiO2 was the reason for this enhanced photocatalytic activity. As a result, it is expected that this approach of photocatalytically active semiconducting nanocatalysts will be used in industry to eliminate undesired organics from the environment.

Rubber Tiles Made from Secondary Raw Materials with Immobilized Titanium Dioxide as Passive Air Protection

The immobilization of titanium dioxide, particularly commercial TiO2 P25, on the surface of recycled rubber tiles presents a solution for achieving passive air protection. A completely new purpose for tiles was obtained by addressing air pollution and related health issues. Modified rubber tiles were prepared using a sol–gel method with three different proportions of TiO2 (2, 4, and 10 g) in the solution. The nature of TiO2 nanoparticles and their respective binding on the tile surface was determined using scanning electron microscopy (SEM) equipped with electron dispersion X-ray spectrometry (EDS) and Fourier-transform infrared (FTIR) spectroscopy. The SEM-EDS results showed that the most successful immobilization was achieved with the lowest amount of TiO2 in the sol–gel solution. The FTIR results confirmed a band at 950 cm−1 that was attributed to the Ti-O-Si bond. The stability and environmental impact of the treated rubber substrates were investigated by a leaching test. Photocatalytic oxidation was confirmed by the oxidation of NH3 to N2. Based on the results obtained, rubber substrates with an addition of 2 g of TiO2 have demonstrated prospects for further tests of the photocatalytic degradation of airborne pollutants.

Cube-like anatase TiO2 mesocrystals as effective electron-transporting materials toward high-performance perovskite solar cells

Electron-transporting materials (ETMs) with higher carrier mobility and a suitable band gap structure play a significant role in determining the photovoltaic performance of perovskite solar cells (PSCs). Herein, cube-like mesoporous single-crystal anatase TiO2 (Meso-TiO2) nanoparticles synthesized by using a facile hydrothermal method were utilized as an efficient ETM for PSCs. The superior semiconducting properties of the Meso-TiO2 based ETM enabled the best power conversion efficiency (PCE) of 20.05% for a PSC. Moreover, the device retained 80% of its initial PCE after being stored in ambient conditions for 20 days under 25 ± 5% relative humidity. In contrast to the commercial TiO2 ETM, the Meso-TiO2 ETM based PSC showed a distinguished interface with better interfacial conditions and improved carrier extraction originating from the cube-like mesoporous single-crystal anatase TiO2 ETM.

Tuning TiO2 Porosity of Multilayered Photoanode Towards Enhanced Performance of Dye Sensitized Solar Cell

In this paper, we prepared Titanium Dioxide (TiO2) based dye sensitized solar cells (DSSC). Downscaling of commercial TiO2 powder have been achieved by systematic ball milling carried out using home-made ball milling device. Thin films were prepared and samples were characterized by XRD, SEM, UV-Vis and I-V. The main objective of this work is to prepare TiO2 based (DSSC) using N3 dye and study the effect of the TiO2 grain size inside the photoanode layer on the efficiency of the solar cell. UV-vis study of nanometer sized TiO2 particles showed that the energy gab has shifted towards the lower wavelength in electromagnetic spectrum (blue shift), and then optical band gap is an indirect and allowed transition. Energy gap calculations of related grain size of showed quantum confinement effect. A sophisticated strategy for TiO2 films consisting of tailoring monolayer, bilayer and trilayer of mixed multisized nanoparticles were adopted and investigated as DSSC electrodes. Our results showed that the dye sensitized solar cells can be substantially altered due to the designs and the particle size distributions of the TiO2 photoelectrode. The maximum efficiency of 0.5% was reached by TiO2 photoelectrode designed as a trilayer with a particles of wide size distribution from about 12 to 340 nm in the middle layer. The approach of light scattering in submicrometer‐sized TiO2 nanoparticles aggregates was adopted in order to interpret the enhancement of our DSSC efficiency over extending the length transported by electromagnetic wave hence to promote the light acquiring efficiency of photoelectrode thin film. The relatively larger particle sizes afford the TiO2 films with both better packing and an increased capability for scattering of the incident electromagnetic wave, and hence improves our DSSC efficiency.

Ultrathin carbon-coated Fe-TiO2-x nanostructures for enhanced photocatalysis under visible-light irradiation

Extending solar-light harvesting regions and improving charge separation are contributing to high-performance semiconductor photocatalysis. In this work, ultrathin carbon-coated Fe-TiO2-x nanostructures were prepared via one-pot calcination strategy for tetracycline degradation under visible-light irradiation. The experimental results showed that the carbon-coated Fe-TiO2-x composites displayed remarkably enhanced visible-light harvesting, and the forbidden band width droped to 2.60 eV. In addition, the transient photocurrent responses and electrochemical impedance spectra indicated the highest charge separation and lowest interfacial migration resistance of carbon-coated Fe-TiO2-x-3% composite, and the fluorescence emission spectra and linear sweep voltammetry curves also supported these above findings. The carbon-coated Fe-TiO2-x-3% sample showed the best photocatalytic performance with a rate constant of 0.02512 min−1 towards tetracycline degradation, approximately 3.02 times that of commercial TiO2, mainly attributed to the formation of Fe doping, oxygen vacancies, and relatively high surface areas.

High-performance gas-liquid-solid optofluidic microreactor with TiO2−x-Ag@HKUST-1/carbon paper for efficient photocatalytic nitrogen fixation to ammonia

The low efficiency of photocatalytic nitrogen fixation to ammonia is determined by the low quantum efficiency photocatalyst and the configuration of the reactor.Therefore, a new method was adopted to introduce a gas-liquid-solid optofluidic microreactor with gas-liquid two-chambers into the photocatalytic nitrogen fixation reaction, and a novel and efficient TiO2−x-Ag@HKUST-1/ carbon paper composite membrane was successfully synthesized. The porous structure of HKUST-1/carbon paper can well adsorb N2, and the uniformly dispersed Ag and Ti3+ in the TiO2−x are bridged by O vacancies to form the Ti3+-Ov-Ag active center. These together improve the activity of photocatalytic nitrogen fixation to ammonia. The experimental results show that the TiO2−x-Ag@HKUST-1/carbon paper composite membrane can continuously reduce N2 to ammonia under visible light, and the yield can reach 10.62 mg.h-1.gcat-1and the corresponding apparent quantum yield (AQY) under 450 nm illumination reaches 2.08%, which is much higher than that of commercial TiO2(P25), HKUST-1, and also higher than most of the reported TiO2-based photocatalysts. This shows the superiority of the gas-liquid two-chambers gas-liquid-solid optofluidic microreactor in photocatalytic nitrogen fixation.This work can also be seen as a step towards the development of high-efficiency continuous photocatalytic nitrogen fixation to ammonia technology.

Fabrication of In(OH)3–In2S3–Cu2O nanofiber for highly efficient photocatalytic hydrogen evolution under blue light LED excitation

This study synthesized the In(OH)3–In2S3 nanosheet via a simple hydrothermal method. The different amounts of In(OH)3–In2S3 nanosheet used to synthesize In(OH)3–In2S3–Cu2O composite by a wet chemical method. FESEM, FETEM, XRD, XPS, BET, UV–vis DRS, and PL spectroscopy characterized the In(OH)3–In2S3–Cu2O composite. Compared with In(OH)3–In2S3 nanosheet, In(OH)3–In2S3–Cu2O composite can exhibit the synergistic effects of higher specific surface area, higher light-harvesting capacity, and accelerating the separation and migration of photogenerated charge carriers. In addition, In(OH)3–In2S3–Cu2O nanofiber was fabricated via a facile electrospinning process at the different amounts of In(OH)3–In2S3 nanosheet. The manufacturing process offers many advantages, such as simplicity, low temperature, and without templates. The effect of operational parameters (such as the reaction conditions of photocatalysts, pH values, sacrificial reagents, and light sources) on the photocatalytic hydrogen production of In(OH)3–In2S3–Cu2O nanofiber was investigated. The results indicate that the appropriate reaction conditions of In(OH)3–In2S3–Cu2O nanofiber can reveal higher efficient photocatalytic water splitting than commercial TiO2 or ZnO nanofiber under blue light LED excitation. Furthermore, In(OH)3–In2S3–Cu2O nanofiber can provide a simple fabrication process, high photocatalytic activity, and high reusability shall be beneficial for the practical application of photocatalytic hydrogen production.

Hierarchical ZnS layers-coated Ti3+-TiO2 nanostructures for boosted visible-light photocatalytic norfloxacin degradation

Self-doped Ti3+-TiO2 and amorphous ZnS layers-coated Ti3+-TiO2 nanostructures were successfully fabricated for via a calcination-ultrasonic synthesis strategy for organic pollutant degradation under visible-light illumination. The experimental results revealed that the synthesized Ti3+-TiO2 clusters displayed efficient visible-light absorption and photocatalytic performance. It was also found that amorphous ZnS layers were formed on the coral-like Ti3+-TiO2 clusters via an ultrasonic synthesis method, and the strongly combined interfaces greatly boosted the charge separation between ZnS layers and self-doped Ti3+-TiO2 clusters. The synthesized Ti3+-TiO2@ZnS-15% heterojunction presented the highest photocatalytic activity with a rate constant of 0.03197 min−1, approximately 9.87 times of commercial TiO2. In addition, the prepared Ti3+-TiO2@ZnS composites also exhibited highly boosted photocatalytic performance towards ciprofloxacin and tetracycline degradation under visible-light illumination compared with those of commercial TiO2, Ti3+-TiO2, and ZnS samples. Finally, the norfloxacin degradation pathways and visible-light photocatalytic mechanism over nanostructured Ti3+-TiO2@ZnS heterojunctions were suggested.

Computational, Investigational Explorations on Structural, Electro-Optic Behavior of Pelargonidin Organic Colorant for TiO2 Based DSSCs

In an expedition for green-energy generation and to lower the cost per watt of solar energy, environmentally friendly biotic colorants were separated from Tectona grandis seeds. The prime colorant in the extract is pelargonidin which sensitizes titanium dioxide (TiO2)-based photo anodes. The pelargonidin-sensitized TiO2 nanomaterials endured structural, photosensitive, spectral and current-voltage interpretations. Frontier molecular orbital analysis, physicochemical and electronic parameter computation, UV–visible and DOS spectral analysis, van der Waals prediction and molecular electrostatic potential map were performed theoretically with Gaussian tools, and IR symmetry response was computed using the crystal maker software package. The pelargonidin-sensitized TiO2-created dye-sensitized solar cells which exhibited capable solar light energy to photon conversion proficiency. For comparative purposes, the commercial P25 Degussa TiO2-based DSSC was also fabricated and its proficiency was analyzed. The commercial TiO2 exhibited 57 % higher proficiency in comparison to the sol-gel-derived TiO2-based DSSC.

Novel synthesis of N-doped TiO2 flower-like microspheres with excellent photocatalytic activity for removal of Cr(VI) and methylene blue

N-doped TiO2 flower-like microspheres (N-TFMs) were synthesized via a novel solvothermal method followed by calcination. It is found that the flower-like microspheres are 600–800 nm in diameter and consist of ultrathin nanosheet with a thickness of ca. 3 nm, which possess a high specific surface area up to 304 m2/g. Besides, N dopant was effectively incorporated into TFMs and no additional nitrogen source was required during calcination. The synthesized N-TFMs exhibit much higher photocatalytic activity for the removal of Cr(VI) and methylene blue than commercial P25 TiO2 under visible-light irradiation. Owing to the advantages of open-type morphology, ultrathin thickness and novel N doping, the synthesized N-TFMs maybe have a wide application prospect in environmental purification.

Novel polypropylene-TiO2:Bi spherical floater for the efficient photocatalytic degradation of the recalcitrant 2,4,6-TCP herbicide

In this work, spherical photocatalytic floaters were fabricated by depositing TiO2:Bi (TBi) particles on polypropylene (PP) spheres (recycled from beer cans). These particles were deposited on the sphere (TBi-sphere) by the spray coating technique and evaluated their performance for the photocatalytic degradation of 2,4,6-trichlorophenol (2,4,6-TCP) herbicide. SEM images demonstrated that the BTi powders consisted in conglomerated grains with sizes of 20–80 nm and the analysis by X-ray diffraction confirmed the presence of rutile and anatase phases in the BTi. The photocatalytic experiments showed that the TBi and TBi-sphere produced maximum degradation of 90 and 97% for 2,4,6-TCP, respectively, after 4 h under UV–Vis light. The photocatalytic powders/composites were reused 3 times and the loss of degradation efficiency was 3 and 16% for the TBi powder and TBi-sphere, respectively. This means that the TBi-sphere is more stable for the continuous degradation of the 2,4,6-TCP contaminant. The TiO2:Bi powder was compared with the commercial TiO2 (P25) and found that the TiO2:Bi powder had higher light absorption (≈42%) and higher surface area (≈105%) than the P25. Therefore, the degradation percentage for the 2,4,6-TCP was 52% higher in the sample doped with Bi. Also, scavenger experiments were carried out and found that the main oxidizing agents produced for the degradation of 2,4,6-TCP were •OH− radicals and •O2− anions. Other species such as h+ were also produced at lower amount. Hence, our results demonstrated that spherical/floatable photocatalytic composites are a viable option to remove herbicide residuals from the water, which is of interest in water-treatment-plants.