Designing a highly near infrared-reflective black nanoparticles for autonomous driving based on the refractive index and principle

HYPOTHESIS

The development of highly NIR reflective black single-shell hollow nanoparticles (BSS-HNPs) can overcome the Light Detection and Ranging (LiDAR) sensor limitations of dark-tone materials. The crystalline phase of TiO2 and the refractive index can be controlled by calcination temperature. The formation of hollow structure and the refractive index is expected to simultaneously increase the light reflection and LiDAR detectability.

EXPERIMENTS

The BSS-HNPs are synthesized using the sol-gel method, calcination, NaBH4 reduction, and etching to form a hollow structure with true blackness. The computational bandgap calculation is conducted to determine the bandgap energy (Eg) of the white and black TiO2 with different crystalline structures. The blackness of the as-synthesized materials is determined by the Commission on Illumination (CIE) L*a*b* color system.

FINDINGS

The hydrophilic nature of BSS-HNPs enables the formulation of hydrophilic paints, allowing the mono-layer coating. With the synergistic effects of hollow structure and the refractive index, BSS-HNPs manifested superb NIR reflectance at LiDAR detection wavelengths. The high detectability, blackness, and hollow structure of BSS-HNPs can expand the variety of LiDAR-detectable dark-tone materials.

Effect of basic and basic/acid modifications on the surface of PVDF membranes for the insertion of TiO2 and its use in environmental applications

Supporting titanium oxide (TiO2) on polymeric membrane surfaces is a strategy to increase the photocatalytic activity of this material as well as to modify membrane surface with antifouling properties or to develop hybrid processes of water treatment. The chemical characteristics of the polymeric membrane surfaces are a determining factor in the correct impregnation of TiO2 particles. In this work, the titanium oxide was immobilized on polyvinylidene fluoride (PVDF) membrane surface by direct impregnation during the synthesis of the inorganic particles by sol-gel route. The PVDF membranes were previously modified by treatments based on an alkaline attack followed by acid treatment. The final TiO2-modified membranes were characterized by infrared and Raman spectroscopy, as well as by scanning electron microscopy. In addition, the changes on the surface characteristics were determined by contact angle measurements. Finally, the membranes were tested on the photocatalytic degradation of methyl orange (MO). The results obtained indicate that the basic/acid pretreatment allows the generation of active sites in the membrane and that when carrying out the synthesis of TiO2 on the membrane, it can be anchored stably on its surface and through the pores. The microscopies indicate that the structure of the membrane is not compromised by the pretreatment. The amount of TiO2 deposited on the membrane was of 0.1580 ± 0.01773 mg TiO2/cm2 membrane. With this amount of TiO2, a degradation percentage of 98.2% is achieved after 450 min; when the membrane is used for a second cycle, a degradation percentage of 82.0% is obtained, which remains constant for 3 subsequent cycles. This method, which uses the PVDF membrane as a support for TiO2 particles, represents a low-cost and easy-to-prepare insertion procedure, with good degradation percentages, which means that the membrane can be used for subsequent studies in filtration systems in the treatment of effluents from the textile industry.

Synthesis of Fluoride-Substituted Layered Perovskites ZnMoO4 with an Enhanced Photocatalytic Activity

Oxyfluorides possess considerable attention for their multiple excellent properties, but the conventional high-temperature solid-state syntheses have seen bottlenecks in the synthesis of new compounds. Herein, we report a novel layered oxyfluoride ZnMoO4:F, which is prepared by a facile hydrothermal method using ZnF2 as the fluoride source. The fluoride anions are successfully introduced into the oxygen sublattice, which is confirmed by a combined analysis using XRD, STEM, and TGA techniques. The as-synthesized ZnMoO4:F has an absorption edge at around 550 nm, indicating a red shift of Eg to the visible region compared to the oxide counterpart. The layered oxyfluoride exhibits an enhanced photocatalytic active for hydrogen evolution under simulated sunlight (λ > 350 nm), and the activity of ZnMoO4:F (651.9 μmol g-1) was 2 times higher than that of ZnMoO4 (309.7 μmol g-1). Further electrochemical analysis has shown that the conduction band position plays a critical role in the high performances of ZnMoO4:F. This work sheds new light on the future design and synthesis of novel fluoride-doped materials for photocatalysis applications.

Hydrothermal Synthesis of FeOOH and Fe2O3 Modified Self-Organizing Immobilized TiO2 Nanotubes for Photocatalytic Degradation of 1H-Benzotriazole

In this study, titanium dioxide nanotubes were prepared by electrochemical anodization technique and modified with an aqueous solution of FeCl3 using hydrothermal synthesis method to control the amount and distribution of iron compounds on the anatase TiO2 nanotubes. The objective was to synthesize immobilized FeOOH@TiO2 or Fe2O3@TiO2 photocatalysts designed for the flow-through reactor systems; to investigate thermal treatment effect on the photocatalytic efficiency; to determine appropriate Fe-compounds concentration for the maximum photocatalytic activity improvement, and to explain the mechanism responsible for the enhancement. The photocatalysts were tested for the degradation of 1H-benzotriazole in water under UV/solar light irradiation. Up to two times increase in the photocatalytic activity was obtained when TiO2 nanotubes were modified with 0.8 mM Fe. At higher Fe concentrations (8 mM and 80 mM), the photocatalytic activity of the given photocatalysts decreased. To confirm the formation of FeOOH or Fe2O3 species, and to clarify the mechanism of photoactivity, X-ray diffraction (XRD), Raman spectroscopy (RS), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray spectroscopy (EDS) and UV-Vis spectroscopy were used.

Highly Characteristic Adsorption Based on Single Crystal {001}-TiO2 Surface Molecular Recognition Promotes Enhanced Oxidation

Exploring the adsorption and selective removal mechanism of target pollutants on the catalytic interface is an important research topic in the field of environmental sewage treatment. However, the molecular recognition based on the surface of single crystals is still unclear. Single crystal molecularly imprinted TiO₂ (001-MI-TiO₂) with a highly exposed {001} plane was prepared by a hydrothermal method to characteristically adsorb and degrade phenol. The kinetics of phenol oxidation on 001-MI-TiO₂ was 12.93 times that of polycrystal nonimprinted TiO₂. The phenol adsorption quantity of 001-MI-TiO₂ was 1.68 times that of the polycrystal molecularly imprinted TiO₂ (MI-TiO₂). Compared with MI-TiO₂, the significantly increased removal of phenol on 001-MI-TiO₂ mainly attributed to the enhanced adsorption quantity and better photocatalytic performance. The recognition mechanism of phenol on the 001-MI-TiO₂ during the adsorption process was studied using attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), which indicated enhanced adsorption of phenol when compared with MI-TiO₂. The recognition between the phenol molecule and the imprinted sites mainly relied on the hydrogen bond between the π bond of the benzene ring and the hydroxyl group on the surface of TiO₂. Besides, the interferent ATR-FTIR results showed that the single crystal surface can significantly reduce noncharacteristic adsorption, indicating good selectivity for the targets. In addition, the degradation intermediates during the photocatalytic process were further analyzed by in situ infrared technology.

Fluorine-programmed nanozipping to tailored nanographenes on rutile TiO2 surfaces

The rational synthesis of nanographenes and carbon nanoribbons directly on nonmetallic surfaces has been an elusive goal for a long time. We report that activation of the carbon (C)–fluorine (F) bond is a reliable and versatile tool enabling intramolecular aryl-aryl coupling directly on metal oxide surfaces. A challenging multistep transformation enabled by C–F bond activation led to a dominolike coupling that yielded tailored nanographenes directly on the rutile titania surface. Because of efficient regioselective zipping, we obtained the target nanographenes from flexible precursors. Fluorine positions in the precursor structure unambiguously dictated the running of the “zipping program,” resulting in the rolling up of oligophenylene chains. The high efficiency of the hydrogen fluoride zipping makes our approach attractive for the rational synthesis of nanographenes and nanoribbons directly on insulating and semiconducting surfaces.

Nucleation of octahedral titanate crystals using waste anodic electrolyte from the anodization of TiO2 nanotubes

Anodization conducted in ethylene glycol with H₂O₂ produces nanotube arrays. Octahedral crystals were extracted from the electrolyte waste for chemical recycling.

Bio-mimicking TiO2 architectures for enhanced photocatalytic activity under UV and visible light

A multi-step chemical replication method using natural green leaves as templates can produce a porous, visible-light active TiO₂-based photocatalyst.

Structural characterization of Ag-doped TiO2 with enhanced photocatalytic activity

Ag-doped TiO₂ nanoparticles with different metallic content (0.5, 2.0, and 5.0% m/m) were prepared using a simple and cost-effective method based on a sol–gel technique, followed by thermal treatment.

Sol–gel synthesis of nanocrystal-constructed hierarchically porous TiO2 based composites for lithium ion batteries

Hierarchically porous TiO₂ based composites have been synthesized by a facile sol–gel method. As anode materials for lithium-ion batteries (LIBs), which exhibit excellent cycling stability and superior rate capability.