Hierarchical Porous TiO2 Research Articles

Au@ZnS core–shell nanoparticles decorated 3D hierarchical porous TiO2 photocatalysts for visible-light-driven CO2 reduction into CH4

Hereby, the core–shell structured Au@ZnS nanoparticles were precipitated on three-dimensionally ordered macro-mesoporous TiO2 (Au@ZnS/3DOMm-TiO2) by GBMR/P method. The slow photon effect of 3DOM structure leads to increase the light trapping and absorption efficiency. The hierarchical porous structure improves the specific surface area of the carrier, providing a larger internal void for desorption of reaction products and additional activation sites for the CO2 reduction. In the all-solid Z-scheme system, electrons are transferred along the direction from TiO2 to Au and finally to the surface of ZnS is realized to participate in the reaction of CO2 reduction. Under irradiation of visible light, ternary Au@ZnS/3DOMm-TiO2-2 catalyst exhibits the highest catalytic activity for CO2 photoreduction with H2O, i.e., the formation rate and selectivity of CH4 product is 33.2 µmol g-1h−1 and 91.5 %, respectively. The design of Z-scheme heterojunctions on 3D macro-mesoporous oxide surfaces are expected to expand new ideas for the preparation of efficient photocatalysts.

3D dendritic hierarchically gradient nanoflowers in situ grown on conductive substrates for efficient hydrovoltaic power generation

3D hierarchical porous TiO2 nanoflowers (HTNFs) with balanced selectivity and permeability for efficient water-droplet-induced hydrovoltaic power generators.

Controllable synthesis of flower-like hierarchical porous TiO2 at room temperature and its affinity application.

Flower-like particles have attracted much attention due to their efficient surface accessible sites and unique hierarchical porous structure. However, their synthesis is usually challenging and requires complex procedures. Herein, we present a simple method for rapid preparation of flower-like hierarchical porous TiO2 (FHP-TiO2) at room temperature for the first time. This method can accurately control the size of FHP-TiO2 from 150 nm to 400 nm by combining co-assembly and Stober reaction. The formation mechanism and influencing factors of FHP-TiO2 were systematically investigated, and its excellent metal oxide affinity was confirmed by theoretical calculations. Due to its hierarchical porous structure, large surface area and high specificity performance, FHP-TiO2 served as an appealing restricted-access adsorbent for specific and efficient enrichment of molecules with phosphate groups in a complex sample matrix, thereby realizing the quantitative analysis of these important biomolecules by coupling with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Moreover, compared with other morphologies (rough surface, and hollow dendritic and mesoporous structure) of TiO2 and flower-like SiO2, FHP-TiO2 showed the best affinity binding ability. This research not only presents a novel approach for tunable room-temperature synthesis of FHP-TiO2 with different sizes, but also expands the application of FHP-TiO2 as an appealing sample-enricher for food safety monitoring and early disease diagnosis.

Highly efficient photoanode in visible light water splitting through development of Z-scheme structure between compositing TiO2 with GQDs and Ba doped VO2 (m) with smart selection of Ag nanoparticles sites

A highly efficient photoanode for water splitting under visible light is designed by placing Ag nanoparticles (NPs) at the interface of Ba doped VO2 (m) (BaV) and compositing hierarchical porous TiO2 NPs with a graphene quantum dots layer (TG). In fact, the electron flow direction in the photoanode is simply adjusted to develop the Z-scheme structure through solution processing assembly. A very high photocurrent of 2.15 mA cm−2 at 1.23 V vs. RHE is achieved for sequentially assembled reduced graphene oxide (RGO)/BaV/Ag/Ag@TG photoanode. This value is 30 times higher than that of pristine TiO2 photoanode (0.07 mA cm−2 at 1.23 V vs. RHE) and a 70 % increase over type-II heterojunction with RGO/Ag@TG/BaV assembly. Importantly, the stability of this Z-scheme photoanode is 10 times higher than its type-II heterojunction counterpart, making it a promising option for practical applications in water splitting under visible light.

A Fluoride-free Approach to Hierarchical Porous Anatase TiO2 Composed of Ultrathin Oriented Graphene-liked Reactive Nanosheets

Hierarchical porous anatase TiO2 is synthesis by a universal solvothermal reaction, However, most synthesis methods are usually carried out in the presence of environmentally unfriendly fluorides. In this study, hierarchical porous anatase TiO2 composed of ultrathin oriented graphene-liked rich in (001) crystal facets were successfully synthesized under fluoride-free conditions. By adjusting the nitrogen doping content, the thickness of the nanosheets was controlled, and the crystals were characterized using X-ray diffraction, scanning electron and transmission electron microscopy, as well as electron spectroscopy.

High-density triple-phase contact points for enhanced photocatalytic CO2 reduction to methanol

The efficiency of photocatalytic CO2 reduction reaction (PCRR) is restricted by the low solubility and mobility of CO2 in water, poor CO2 adsorption capacity of catalyst, and competition with hydrogen evolution reaction (HER). Recently, hydrophobic modification of the catalyst surface has been proposed as a potential solution to induce the formation of triple-phase contact points (TPCPs) of CO2 (gas phase), H2O (liquid phase), and catalysts (solid phase) near the surface of the catalyst, enabling direct delivery of highly concentrated CO2 molecules to the active reaction sites, resulting in higher CO2 and lower H+ surface concentrations. The TPCPs thus act as the ideal reaction points with enhanced PCRR and suppressed HER. However, the initial synthesis of triple-phase photocatalysts tends to possess a lower bulk density of TPCPs due to the simple structure leading to limited active points and CO2 adsorption sites. Here, based on constructing a hydrophobic hierarchical porous TiO2 (o-HPT) with interconnected macropores and mesopores structure, we have significantly increased the density of TPCPs in a unit volume of the photocatalyst. Compared with hydrophobic macroporous TiO2 (o-MacPT) or mesoporous TiO2 (o-MesPT), the o-HPT with increased TPCP density leads to enhanced photoactivity, enabling a high methanol production rate with 1111.5 µmol g−1 h−1 from PCRR. These results emphasize the significance of high-density TPCPs design and propose a potential path for developing efficient PCRR systems.

MXene/Fluoropolymer‐Derived Laser‐Carbonaceous All‐Fibrous Nanohybrid Patch for Soft Wearable Bioelectronics (Adv. Funct. Mater. 21/2023)

Laser-Carbonization In article number 2208894, Jae Y. Park and co-workers, report an electrochemical-electrophysiological multimodal biosensing patch based on MXene/fluoropolymer nanofibers (MFNFs)-derived hierarchical porous TiO2 nanocatalyst interconnected three-dimensional fibrous carbon nanohybrid electrodes. The nanohybrid electrode is produced via a one-step laser carbonaceous thermal oxidation of MFNFs. The nanohybrid modified biosensing patch integrated into textile is demonstrated to be capable of simultaneously and precisely monitoring sweat glucose with pH adjustment and electrocardiogram signals.

Phase control and induction of visible-light photocatalytic activity in hierarchical porous structure nanocrystalline TiO2 prepared using a MOF-5-derived nanoporous carbon template

BackgroundNanocasting is a powerful method to induce unique structural and morphological characteristics. It is known that the phase, morphology, and nanostructure of TiO2 facilitate its photocatalytic performance and band gap energy. In this context, we simultaneously controlled the TiO2 phase and improved its photocatalytic activity by choosing the appropriate carbon substrate and synthesis process. MethodsIn this study, a high surface area nanoporous carbon with an extremely interconnected mesoporous network and accessible pores in terms of depth and size was derived from MOF-5. This hard template used for the synthesis of titanium oxide (TiO2) nanoparticles by nanocasting. in addition to the anatase phase, the brookite phase was successfully produced using this nanocasting approach by penetrating NaF solution to the template pores under hydrothermal conditions. Significant FindingsThe results showed that, the interconnected mesoporous network of the carbon template led to the formation of brookite and anatase TiO2 with highly developed mesoporous and macroporous structures and very high surface areas of 109 and 126 m2g−1, respectively. Furthermore, the fabricated brookite and anatase showed enhanced photocatalytic efficiency in visible light because of the increase in light harvesting ability and the reduction in band gap energy to 2.84 and 2.60 eV, respectively.

MXene/Fluoropolymer‐Derived Laser‐Carbonaceous All‐Fibrous Nanohybrid Patch for Soft Wearable Bioelectronics

AbstractWhile state‐of‐the‐art skin‐adhering fibrous electrodes have distinct benefits in personal wearable bioelectronics, considerable challenges persist in the production of fibrous‐based soft conductive biosensing nanomaterials and their integration into efficient multisensing platforms. Here, an electrochemical‐electrophysiological multimodal biosensing patch based on MXene/fluoropolymer nanofiber‐derived hierarchical porous TiO2 nanocatalyst interconnected 3D fibrous carbon nanohybrid electrodes is reported. The nanohybrid electrode is produced via a one‐step laser carbonaceous thermal oxidation, resulting in excellent elctroconductivity (sheet resistance = 15.6 Ω sq−1), rich active edges for effective electron transmission, and abundant support for enzyme immobilization. The features are attributed to three synergistic effects: i) conductivity of the interior, unoxidized MXene layers, ii) quick heterogeneous electron transmission of the exterior TiO2 nanoparticles, and iii) the porous disordered carbon's electron “bridge” effects. Based on the foregoing, the nanohybrid modified biosensing patch integrated into textile is demonstrated to be capable of simultaneously and precisely monitoring sweat glucose with pH adjustment (sensitivity of 77.12 µA mm−1 cm−2 within physiological concentrations of 0.01–2 × 10−3 m) and electrocardiogram signals (signal‐to‐noise ratio = 37.63 dB). This novel approach paves the way for controlled investigations of the nanohybrid, for several functionalization and design options, and for the mass manufacturing capabilities required in real‐world applications.

Controllable preparation and photocatalytic performance of hollow hierarchical porous TiO2/Ag composite microspheres

Mesoporous titania-based composites have attracted much attention in the world due to their large specific surface area, high material transport efficiency, and photocatalytic efficiency. The hollow and hierarchical porous structure is rarely involved in a binary photocatalytic material. In the present work, a novel type of hollow hierarchical porous TiO2/Ag composite microsphere with tunable microstructure was successfully prepared by simple solution methods, including sol-gel method, template method and impregnation method. Hollow hierarchical porous TiO2 microspheres were prepared by a sol-gel process with P123 as a hierarchical pore structure guide agent and template method with polystyrene microspheres as a hollow hard template. Further, hollow hierarchical porous TiO2/Ag composite microspheres were obtained by modifying Ag in the hollow hierarchical porous TiO2 microspheres by the impregnation method. The different hollow hierarchical porous TiO2/Ag composite microspheres are obtained by changing the molar ratio R of Ti/Ag. The optimal addition amount of Ti and Ag in sample HHPA6 (10:0.5) is the molar ratio of 10:0.5, and the experimental value of XPS is the molar ratio of 10:0. 91. Compared with the hollow hierarchical porous TiO2 microspheres, the excitation wavelength of composite microspheres is shifted to the visible light direction by 24 nm, and their response range and their light utilization rate were improved. When the molar ratio R of Ti/Ag is 10:0.5, hollow hierarchical porous TiO2/Ag composite microspheres have a specific surface area of 177 m2/g, the pore volume of 0.37 cm3/g, and the primary and secondary pore size of 4.04 nm and 7.74 nm, respectively. It shows the highest photocatalytic activity in the ultraviolet band of 365 nm and 395 nm, and the degradation rate of methyl orange solution is 96.84% and 98.65%, respectively. Their excellent photocatalytic performance is attributed to their special structure combining hierarchical pores and hollow structures as well as the synergistic effect of Ag and TiO2.

Immunomodulation and osteointegration of infected implants by ion-riched and hierarchical porous TiO2 matrix

Immunomodulation and osteointegration of infected implants by ion-riched and hierarchical porous TiO2 matrix

Hierarchical porous TiO2 with a uniform distribution of anchored gold nanoparticles for enhanced photocatalytic efficiency and accelerated charge separation for the degradation of antibiotics.

A novel approach to synthesize porous Au/TiO2 nanocomposites has been achieved through a pyrolytic strategy by employing NH2-MIL-125(Ti) as a TiO2 precursor, and photo-deposition of Au nanoparticles (NPs) onto porous nanocrystalline TiO2 with varying Au contents (0.05-0.5%). TEM images of Au/TiO2 nanocomposites showed that TiO2 particles were spherical structures, highly dispersed, and homogeneous with diameters of 10-15nm, and Au NPs (20-30nm) were anchored onto porous TiO2 matrices with a uniform distribution. The synthesized Au/TiO2 nanocomposites were assessed through the degradation of two antibiotic models, metronidazole (MNZ), and trimethoprim (TMP), under visible light and compared with undoped TiO2 and commercial TiO2 (P-25). The synthesized Au/TiO2 photocatalyst revealed enhanced photocatalytic performance in the mineralization (80%) and degradation (100%) of MNZ and TMP in both water matrices compared to undoped TiO2 (60%, 76%) and commercial P-25 (48%, 65%). The obtained 0.1% Au/TiO2 nanocomposite could complete the mineralization of TMP and MNZ with rate constant values (4.47 × 10-3min-1 and 5.23 × 10-1min-1) owing to the large well-developed porosity and high surface area of TiO2 and the small size of Au NPs with high dispersity, surface plasmon resonance, and stability. The recyclability of the 0.1% Au/TiO2 nanocomposite exhibited high durability without the leaching or loss of photocatalytic performance after four cycles. Complete degradation was achieved within 100min in the water matrix from real wastewater, indicating promising results for the degradation of pharmaceuticals in the different water matrices. The present work opens a new route to synthesize low-cost, effective, and high photocatalytic performance nanocomposites with a small Au content as a cocatalyst onto semiconductor materials.

Design and synthesis of glycopolymers for efficient photocatalytic hydrogen evolution

Saccharide-based homopolymers (PMDG and PMDM) and diblock copolymers with 9-vinylcarbazole (PNVK-b-PMDG and PNVK-b-PMDM) were synthesized by deacetylation of RAFT-generated corresponding acetyl-glucopyranoside and acetyl-maltose polymer segments. Synthesized polymers chemical structures were authenticated by spectroscopic methods. SEC investigational values of the polymers’ weight average molecular weights (Mw) were obtained in the orbit of 1849–11166 g/mol with 1.14–1.57 range polydispersity (Ð). The acetylated di-block copolymers exhibited higher thermal stability (Td5%: 265–274 °C) than the corresponding homopolymers (Td5%: 259–261 °C). The acetylated di-block copolymers showed higher Tg values (54–67 °C) than the corresponding deacetylated polymers (52 °C). The glycopolymers with hierarchical porous TiO2 (HPT) semiconductor photocatalyst exhibited relatively long lived charge carriers for efficient photon harvesting and enabling them to efficiently drive sacrificial H2 generation in aqueous NaOH under visible light. The hydrogen production rate gradually increased from 109 μmol g−1 h−1 to 881 μmol g−1 h−1 when the NaOH concentration was boosted from 1 M to 10 M using PNVK-b-PMDG as a sacrificial electron donor with HPT and platinum. The glucose-based PNVK-b-PMDG diblock copolymer exhibited higher hydrogen production of 881 μmol g−1 h−1 with an apparent quantum efficiency (AQY) of ∼ 2.15 % than the di-block from maltose (PNVK-b-PMDM) [730 μmol g−1 h−1, AQY: ∼1.78 %] in the presence of alkaline condition (aqueous NaOH, pH = 10). The pendant carbazole moieties of the diblock copolymers improved the efficiency of photocatalytic H2 production by facilitating interaction of free –OH groups of the glycopolymer segment with the HPT which provide significant increase in the reduction potential and decrease of the charge recombination. This work could lead to a more efficient photoreforming path of novel glycopolymer to harvest renewable H2 energy.

The synthesis of biotemplate‐based Bi2WO6/TiO2 composite photocatalyst for degradation of microcystin

AbstractMicrocystin is a harmful hepatic toxin produced by cyanobacteria, is a serious threat due to its toxicity to water ecosystems, and it is found recently that TiO2 photocatalyst is effective in degradation of microcystin. In this study, hierarchical porous Bi2WO6/ TiO2 composite photocatalysts were synthesized with a novel hydrothermal method by using rice husk as the biological template. The results showed that the original micro‐ and nanopores of rice husk were efficiently replicated by the synthesized porous TiO2 photocatalyst with a specific surface area of 137.09 m2/g, which increased by nearly 100 m2/g over the surface area. SEM, TEM, XRD, and XPS spectra showed that heterogeneous structures were formed by Bi2WO6 and TiO2, with which process the crystal structures of both were not affected. In the meantime, we studied the effect of hierarchical porous TiO2 photo‐catalyst, pure TiO2 photo‐catalyst, Bi2WO6 photo‐catalyst, Bi2WO6/ hierarchical porous TiO2 photo‐catalyst on degradation of 1 mg/L MC‐LR, and the results showed that to use the unique silicon‐carbon structure of rice husk to prepare hierarchical porous TiO2 photo‐catalyst can have the degradation rate of 53.5%, which is higher than that of commercially available TiO2 photo‐catalyst by 13.8%. Compared with a single photo‐catalyst, the photo‐catalytic activity of Bi2WO6/ hierarchical porous TiO2 photo‐catalyst is significantly improved. The optimal mingling amount of Bi2WO6 is 0.2 mol/mol. At this time, the degradation rate of MC‐LR is 85.3%, and the main active substances for degradation are h+ and ·OH. In addition, the degradation process of MC‐LR fit well with the kinetic model of Quasi Primary Reaction. The insight of green synthesis of Bi2WO6/ TiO2 composite photocatalysts for degradation of microcystins was provided by this study.

Three-Dimensional Hierarchical Porous TiO2 for Enhanced Adsorption and Photocatalytic Degradation of Remazol Dye.

Three-dimensional hierarchical mesoporous structures of titanium dioxide (3D-HPT) were synthesized by self-assembly emulsion polymerization. Polymethyl methacrylate (PMMA) and pluronic 123 (P123) were used as the soft templates and co-templates for assisting the formation of hierarchical 3D porous structures. The TiO2 crystal structure, morphology, and Remazol red dye degradation were investigated. The 3D-HPT and normal three-dimensional titanium dioxide (3D-T) presented the good connection of the nanoparticle-linked honeycomb within the form of anatase. The 3D-HPT structure showed greatly enhanced adsorption of Remazol dye, and facilitated the efficient photocatalytic breakdown of the dye. Surprisingly, 3D-HPT can adsorb approximately 40% of 24 ppm Remazol dye in the dark, which is superior to 3D-T and the commercial anatase at the same condition (approx. 5%). Moreover, 3D-HPT can completely decolorize Remazol dye within just 20 min, which is more than three folds faster than the commercial anatase, making it one of the most active photocatalysts that have been reported for degradation of Remazol dye. The superior photocatalytic performance is attributed to the higher specific surface area, amplified light-harvesting efficiency, and enhanced adsorption capacity into the hierarchical 3D inverse opal structure compared to the commercial anatase TiO2.

Controlled Loading of MoS2 on Hierarchical Porous TiO2 for Enhanced Photocatalytic Hydrogen Evolution

Controlled Loading of MoS₂ on Hierarchical Porous TiO₂ for Enhanced Photocatalytic Hydrogen Evolution

Tailoring hierarchical porous TiO2 based ternary rGO/NiO/TiO2 photocatalyst for efficient hydrogen production and degradation of Rhodamine B

This study reports a facile and cost effective approach for synthesizing a ternary photocatalyst rGO/NiO/TiO2 (RGNPT) based on three-dimensionally hierarchical porous TiO2 (PT) particles, rGO and NiO as a cocatalyst for efficient photocatalytic hydrogen generation. The efficient junction architecture of RGNPT was observed from the TEM study. The composite's morphology was tuned by varying the weight ratio variation of graphene oxide (5, 7.5, and 10 Wt%). The obtained material showed impressive photocatalytic efficiency for H2 production in aqueous methanol suspension. The p-n junction hybrid composite RGNPT-7.5Wt% showed superior activity towards H2 production yield 8,215 µmolg−1 after 4 h of light irradiation and apparent quantum yield efficiency 9.19%. The photocatalyst shows promising results of 88% of photo-degradation efficiency to Rhodamine B (Rh-B) dye. The RGNPT-7.5Wt% demonstrated the higher current density 0.16 µAcm−2 whereas NiO-porous TiO2 (NPT) showed ten folds lower of 0.017 µAcm−2 using Ag/AgCl electrode. The electron impedance spectroscopic results of RGNPT-7.5Wt% heterostructure exhibited higher photocurrent response and lower charge transfer resistance and significantly accelerate the electrons transfers across the NPT and NiO. Photoluminescence lifetime of RGNPT-7.5Wt% (τ = 3.21 ns) is 16 times higher than porous TiO2 (τ = 0.10 ns). This work manifestates that hierarchical porous TiO2 and rGO graphene plays a vital role in the electron transfer pathway, which is further considered an excellent strategy for synthesizing the ternary composites and enhancing photocatalytic hydrogen production.

Non-oxidative Coupling of Methane: N-type Doping of Niobium Single Atoms in TiO2 -SiO2 Induces Electron Localization.

Photodriven nonoxidative coupling of CH4 (NOCM) is an attractive potential way to use abundant methane resources. Herein, an n-type doped photocatalyst for NOCM is created by doping single-atom Nb into hierarchical porous TiO2 -SiO2 (TS) microarray, which exhibits a high conversion rate of 3.57 μmol g-1 h-1 with good recyclability. The Nb dopant replaces the 6-coordinated titanium on the (1 0 1) plane and forms shallow electron-trapped surface polarons along [0 1 0] direction and the comparison of different models proves that the electron localization caused by the n-type doping is beneficial to both methane activation and ethane desorption. The positive effect of n-type dopant on CH4 conversion is further verified on Mo-, W- and Ta-doped composites. In contrast, the doping of p-type dopant (Ga, Cu, Fe) shows a less active influence.

Non‐oxidative Coupling of Methane: N‐type Doping of Niobium Single Atoms in TiO2–SiO2 Induces Electron Localization

AbstractPhotodriven nonoxidative coupling of CH4 (NOCM) is an attractive potential way to use abundant methane resources. Herein, an n‐type doped photocatalyst for NOCM is created by doping single‐atom Nb into hierarchical porous TiO2–SiO2 (TS) microarray, which exhibits a high conversion rate of 3.57 μmol g−1 h−1 with good recyclability. The Nb dopant replaces the 6‐coordinated titanium on the (1 0 1) plane and forms shallow electron‐trapped surface polarons along [0 1 0] direction and the comparison of different models proves that the electron localization caused by the n‐type doping is beneficial to both methane activation and ethane desorption. The positive effect of n‐type dopant on CH4 conversion is further verified on Mo‐, W‐ and Ta‐doped composites. In contrast, the doping of p‐type dopant (Ga, Cu, Fe) shows a less active influence.

Investigation of microstructure and photocatalytic activity of quartz sand composite supported by hierarchical porous TiO<sub>2</sub>

Investigation of microstructure and photocatalytic activity of quartz sand composite supported by hierarchical porous TiO<sub>2</sub>