Carbon-coated TiO2 Research Articles

Preparation of C@CuNi/TiO2 with a local surface plasmon resonance for photocatalytic degradation of organic dyes and antibiotics under visible light irradiation

A composite photocatalyst with carbon-coated CuNi nanoparticles-loaded TiO2 nanotubes (C@CuNi/TiO2) was synthesized via a microwave hydrothermal alkali stripping method combined with subsequent in-situ carbothermal reduction. The structure, morphology, and surface chemical composition were investigated using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The findings demonstrate that the microwave hydrothermal alkali peeling enables the formation of a three-dimensional C@CuNi/TiO2 composite structure. The results of transient photocurrent response (i-t) and electrochemical impedance spectroscopy under visible light demonstrate that C@CuNi/TiO2 exhibits a reduced rate of electron-hole recombination and lower surface resistance compared to C@TiO2, C@Cu/TiO2, and C@Ni/TiO2. After a two-hour exposure to visible light, the composite photocatalyst C@CuNi/TiO2, featuring a molar ratio of 2 % CuNi nanoparticles to TiO2 nanotubes, exhibited remarkable degradation activity towards organic dyes (Rhodamine B (RhB), Methylene Blue (MB), Methyl Orange (MO)), as well as antibiotics (tetracycline (TC) and levofloxacin (LVFX)). After 5 cycles of photocatalytic reaction, the photodegradation activity of RhB remained above 79 %. It is indicated that CuNi nanoparticles effectively trap and enrich photoelectrons through the photoexcitation of TiO2 nanotubes. Additionally, the local surface plasmonic resonance (LSPR) effect of CuNi nanoparticles reduces the recombination rate of photogenerated electron/hole and the electron transport resistance in the composite photocatalyst, thereby enhancing its overall photocatalytic activity.

An innovative synthesis of carbon-coated TiO2 nanoparticles as a host for Na+ intercalation in sodium-ion batteries.

In this work, an innovative route to synthesize an anatase TiO2@C composite is presented. The synthesis was conducted using a soft chemistry microwave-assisted method using titanium(IV) butoxide as a titanium precursor. The residual (un)converted titanium precursor remaining after TiO2 synthesis was used as a carbon precursor and thermally treated under H2 to obtain nanoparticles of the TiO2@C composite. A superior reversible specific capacity was obtained with TiO2@C (120 mA h g-1 at a C/20 rate, 3rd cycle) compared to that with pristine TiO2 (66.5 mA h g-1 at a C/20 rate, 3rd cycle), in agreement with the importance of carbon coating addition to TiO2 nanoparticles as negative electrode materials for sodium-ion batteries.

Metal-organic framework derived S-doped anatase TiO2@C to store Na+ with high-rate and long-cycle life

The design of a reasonable structure and component regulation are valid methods for enhancing the electrochemical properties of TiO2, which serves as prominent anode in sodium-ion batteries with exceptional structural stability. Herein, the carbon-coated anatase TiO2 doped with S (S-TiO2 @C) was synthesized via a facile metal-organic framework-assisted approach. The S atoms partially substitute oxygen atoms in the lattice, thereby enhancing the capacitive behavior, facilitating charge transfer kinetics, and augmenting the diffusion coefficient of Na+. With exceptionally high porosity and substantial carbon content, the caky S-TiO2 @C electrode manifests superior rate capability of 167.7 mAh g−1 at 5.0 A g−1 and long-cycle life of 239.0 mAh g−1 at 2.0 A g−1 over 4000 cycles. It is foreseeable that the strategy of anionic doping and carbon coating on the metal oxide with porous structure to optimize the sodium storage capability of the electrode will be applied in the future.

Hydrothermal synthesis of carbon-coated mixed crystalline phase TiO2 nanoparticle carbon microsphere composites as high performance anode materials for Li-ion batteries

Hydrothermal synthesis of carbon-coated mixed crystalline phase TiO2 nanoparticle carbon microsphere composites as high performance anode materials for Li-ion batteries

Nanoengineering of N-doped carbon-coated anatase TiO2 nanoparticles for high-performance sodium ion battery

Nanoengineering of N-doped carbon-coated anatase TiO2 nanoparticles for high-performance sodium ion battery

Freestanding TiO2 Nanoparticle-Embedded High Directional Carbon Composite Host for High-Loading Low-Temperature Lithium–Sulfur Batteries

Improving the low-temperature performance of lithium–sulfur batteries is significant for future applications. Meanwhile, a low temperature often leads to sluggish charge transfer kinetics and low energy output. Herein, we designed a thick freestanding TiO2 nanoparticle-embedded three-dimensional carbon composite (TiO2@C@CSC) host with high directional channels, aiming at achieving a high-performance low-temperature lithium–sulfur battery. The carbon-coated TiO2 nanoparticles (TiO2@C) are derived from polyimide-coated TiO2 nanoparticles and embedded in the channels. The chitosan-foam-derived carbon framework (CSC) has vertically aligned channels, which kinetically accelerates ion/electron transport and precisely confines sulfur/polysulfides within its channels. TiO2@C nanoparticles could facilitate the adsorption and conversion of polysulfides. The combination of vertically aligned channels and TiO2@C nanoparticles further provides a chemical gradient that prevents the diffusion of polysulfides and enhances the reaction kinetics at low temperatures. The designed host also has enough accommodation space, which is beneficial to improving the mass loading and utilization efficiency of active sulfur. Finally, the energy storage performance of TiO2@C@CSC as a sulfur host was investigated under 30, −20, and −40 °C. Under 30 °C, the initial discharge capacity of TiO2@C@CSC is 679 mAh g–1 at 1C with 4.0 mg cm–2 sulfur, and an initial capacity of 969 mAh g–1 could be obtained at 0.1C with the sulfur loading mass of 10.0 mg cm–2. Under −20 °C, the performance of TiO2@C@CSC with loading masses of 2.5, 5.0, 10.0, and 20.0 mg cm–2 was investigated, and the corresponding initial capacities at 0.05C were 1573, 924, 242, and 13 mAh g–1, respectively. As the temperature drops to −40 °C, the efficiency becomes lower but the charge–discharge process can still be complete. This work presents a promising direction for developing high-energy low-temperature lithium–sulfur batteries.

Carbon-coated TiO2 anode with solid electrolyte interphase engineered by Ca(ClO4)2 as electrolyte additive towards superior sodium storage

Sodium-ion batteries (SIBs) have attracted much attention for their high energy densities and low cost. However, the unstable solid-liquid interphase seriously restricts the development and application of SIBs. Herein, Ca(ClO4)2 as a new-type electrolyte additive is developed to engineer the solid-liquid interphase of carbon-coated anodes. In the electrolyte with an appropriate concentration of Ca(ClO4)2, Ca2+ can insert into the carbon coating and form a passivation layer during the first cycle, reducing the irreversible sodium-ion capture in the carbon coating and the electrolyte decomposition at the solid-liquid interface. Thus, the carbon-coated anode with a thin and stable solid electrolyte interphase (SEI) layer formed realizes the superior sodium storage performance with enhanced sodium-ion diffusion kinetics. Specifically, after adding 0.015 M Ca(ClO4)2 into the electrolyte, the reversible capacity of carbon-coated TiO2 anode could be greatly improved from 271.2 mAh g−1 to 335.1 mAh g−1 at 50 mA g−1, with the initial coulombic efficiency increasing from 41.2 % to 48.7 %. This study provides an alternative strategy to optimizing the SEI layer of carbon-coated TiO2 anode for superior sodium storage property, which also can be applied to other carbon-coated anodes for SIBs.

Carbon-Coated Flower-Like TiO2 Nanosphere as an Ultrastable Anode Material for Potassium-Ion Batteries: Structure Design and Mechanism Study

Carbon-Coated Flower-Like TiO₂ Nanosphere as an Ultrastable Anode Material for Potassium-Ion Batteries: Structure Design and Mechanism Study

Ni/CNTs and carbon coating engineering to synergistically optimize the interfacial behaviors of TiO2 for thermal conductive microwave absorbers

With the coming of 5G era, endowing the microwave absorbers with a light weight and a high thermal conductivity is crucial yet challenging. Combining dielectric/magnetic components with the abundant heterointerfaces has been considered as a promising approach for the development of functional materials with excellent microwave absorption (MA) performances. Herein, we successfully constructed a hierarchical hetero-nanobrush architecture with carbon-coated TiO2 as a backbone decorated by Ni-catalyzed carbon nanotubes (TiO2@C-Ni/CNTs) for excellent MA and thermal management application, and investigated the influence of the Ni/CNTs content on its MA property. CNTs and the well-distributed Ni nanoparticles on top can promote dielectric behaviors and magnetic performances of composites, which is beneficial to the formation of dielectric and magnetic coupling network. Furthermore, the multiple core-shell structures included in TiO2@C-Ni/CNTs composites have the vast heterogeneous interfaces, which can result in multiple relaxation and effective interfacial polarization. Under the synergic action of the conductive loss, interface polarization, and three-dimensional spatial network structure, as-synthesized TiO2@C-Ni/CNTs nanobrushes possess superior MA performances with the minimum reflection loss (RL) of −32.3 dB at 17.3 GHz with a thickness of 1.6 mm and the broadest effective absorption bandwidth (EAB) of 5.5 GHz with a thickness of 1.8 mm. Furthermore, the thermal conductivities and diffusivities of the TiO2@C-Ni/CNTs/nature rubber hybrids are also effectively enhanced. This work provides an idea to design magnetic-dielectric composite nanostructures for MA and thermal management materials.

Synthesis of monolayer carbon-coated TiO2 as visible-light-responsive photocatalysts

Increasing visible light absorption and constructing an active surface for TiO2 have long been pursued to obtain high photocatalytic activities. Modifying TiO2 at an atomic scale is desirable to optimize its surface state and band structure but remains a huge challenge. Herein, we developed an ultrasmall (∼5 nm) visible-light-responsive TiO2 photocatalyst with a novel hybrid structure (TiO2/C) through a chemical vapor deposition process on large scale. Environmental in-situ transmission electron microscope studies confirmed the anatase TiO2 with a monolayer carbon shell in a hybrid structure. The resulted structure possesses narrowed bandgap 2.83 eV, favoring the enhanced visible-light-responsive photocatalytic activity. Density functional theory (DFT) simulations confirm the tunable mechanism of carbon-induced localized energy band within the bandgap of TiO2. As a physical barrier without turning TiO2 black, the monolayer carbon shell stabilizes Ti3+ inside TiO2, facilitates the separation of photo-induced carriers and enriches abundant absorbing sites of target pollutants. Consequently, the TiO2/C exhibits outstanding photocatalytic performance in both photoelectrochemical water oxidation and dye degradation under visible light besides superior activity for hydrogen evolution under simulated sunlight irradiation. This design proved a meaningful strategy in obtaining visible-light-responsive photocatalysts with a stable active surface for industrial application.

Nitrogen-impregnated carbon-coated TiO2 nanoparticles for N2 reduction to ammonia under ambient conditions

Various methods for ammonia production are being studied world wide. The electrochemical nitrogen reduction reaction (eNRR) has been considered an ideal eco-friendly approach for ammonia production. In this study, we proposed a nitrogen-impregnated carbon coating strategy to increase the activity of TiO2-based catalysts for eNRR. Electrochemical measurements revealed that TiO2@N-C resulted in a higher ammonia yield rate (5.302 μg h−1 cm−2) and enhanced Faradaic efficiency (2.46%) at −0.1 V vs. reversible hydrogen electrode in 0.1 M KOH electrolyte. The N-impregnated carbon coating enhanced electron conductivity and electrocatalytic activity, which indicates better performance of the eNRR.

Killing two birds with one stone: Silver nanoparticles loaded on ultrathin N-doped carbon-coated TiO2 porous spheres with narrow bandgap for efficient SERS sensing and photoinduced antibacterial applications

The bifunctional applications of noble metal-TiO2 heterojunctions are an interesting topic, such as antibacterial agents and chemical sensors via surface-enhanced Raman spectroscopy (SERS). The vital factor is to narrow the bandgap of TiO2 and shift the absorption wavelengths from ultraviolet to visible region. In this study, we reported the design and the fabrication of TiO2 spheres coated with an ultrathin nitrogen-doped carbon (NC) shell and subsequent loading Ag nanoparticles. This strategy endowed TiO2 spheres with a narrow bandgap (2.34 eV) and high fluorescence quenching ability. The TiO2@NC/Ag composites exhibited excellent charge transfer-induced SERS performance with high enhancement factor of 8.0 × 106 and good uniformity. The composites were further developed as a SERS sensor for rapid detection of phenformin hydrochloride in human urine with a low detection limit of 5 nM. In the antibacterial application, TiO2@NC/Ag showed a promising bactericidal feature against Escherichia coli under low-power LED (6 W) irradiation, which immensely emerged the synergistic antibacterial role of TiO2@NC and Ag. The inhibition rate under the LED irradiation for 8 h increased from 59.8% to 87.6% as compared to the rate in the dark.

Integrated heterojunction and photothermal effect multiple enhanced ratiometric electrochemiluminescence immunosensor based on calcination controlled and tunable TiO2 mesocrystals

Stratifin (SFN) is considered to be a new biomarker of cancers. In clinical medicine, combining tissue chip technology and immunohistochemical methods qualitatively prove that the abnormal expression of SFN is related to cancer. However, the quantitative detection of SFN is rarely performed. Herein, an ultrasensitive ratiometric ECL immunosensor was constructed to realize SFN determination. A polyvinylpyrrolidone (PVP)-assisted synthesis of TiO2 (PVP-TiO2)@Poly[(9,9-dioctyfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadia-zol-4,8-diyl)] (PFBT) nanomaterial with anodic ECL signal and carbon-coated TiO2 (C-TiO2)-loaded graphitic carbon nitride quantum dots (g-C3N4 QDs) with cathodic ECL signal were firstly used as a pair of luminophores to generate two potential-resolved ECL signals. PVP-TiO2 provided a substrate for the immobilization of biomolecules. C-TiO2 due to the high specific surface area loaded a large amount of g-C3N4 QDs, thereby increasing the ECL intensity. Not only that, the heterojunction formed by semiconductors could also further enhance ECL signal. Impressively, PFBT-C-TiO2 conjugation possessed outstanding photothermal property, which could serve as photothermal convertor device and accelerate the electrochemical mass transfer on the electrode surface, further amplified ECL signal. The ratiometric biosensor showed good linear response for SFN from 10−6ng mL–1 to 0.1 ng mL–1 with a detection limit of 0.33 fg mL–1.

TiO2/C tetragons with a double-side concave nanostructure and its high rate performance on Na-ion storage

TiO2 is acting as a low-cost and promising candidate for a high capacity anode material of Na-ion batteries. Its insufficient cyclability and poor capacity utilisation for Na-ion storage can be improved by manipulating its nanostructures. We designed and prepared a carbon-coated TiO2 (TiO2/C) material with a double-side concave structure and a large surface area. The as-synthesised TiO2/C with such special nanostructure, delivered a high capacity of ca. 175 mAh g−1 at 1 A g−1 rate with roughly 100% capacity retention over 1600 cycles and ca. 100% Coulombic efficiency. More significantly, TiO2/C concave tetragons exhibited an outstanding rate capacity of 150 mAh g−1 and 60 mAh g−1 at 5 A g−1 and 20 A g−1, respectively. These results demonstrate the design of the special TiO2/C concave tetragons allows a sufficiently long cycle life for battery applications, superior reversibility and enhanced rate for the Na-ion storage.

In-situ carbon-coated TiO2 boosting the visible-light photocatalytic hydrogen evolution

A straightforward hydrolysis–carbonization strategy for synthesizing carbon-coated TiO2 photocatalyst is developed. During the calcination process, boric acid functions as a template to maintain the size of TiO2 nanoparticles, expose more active surfaces, and further improve photocatalytic activity. And butyl alcohol generated from the hydrolysis of butyl titanate is carbonized and covered on the surface of TiO2 nanoparticles, forming in-situ carbon-coated TiO2 photocatalyst. Under the irradiation of Xenon lamp, the catalyst TiO2-500-W shows excellent photocatalytic hydrogen evolution ability (434.91 μmol h−1 g−1) and recycling stability. The band gap of carbon-coated TiO2-500-W is 2.82 eV so that it can even promote the hydrogen evolution under visible-light irradiation. Experiments and DFT calculations reveal that the presence of carbon sheet on TiO2 can reduce the band gap, generate valence band tail, and decrease the work-function, which facilitate the improvement of photocatalytic activity for H2 evolution.

Monodisperse core-shell Li4Ti5O12@C submicron particles as high-rate anode materials for lithium-ion batteries

Monodisperse spinel Li4Ti5O12 (LTO) particles coated with a carbon layer (LTO@C) are prepared by using a solid-phase sintering reaction between pre-synthesized carbon-coated TiO2 particles and lithium carbonate. The core-shell structured LTO@C particles have an average size of about 320 nm, and a carbon shell thickness of about 10 nm. While the TiO2 particles that are pre-coated with a carbon layer generate LTO@C particles with monodisperse un-aggregated morphology, the TiO2 particles without carbon coating eventually lead to aggregated LTO particles with an irregular morphology. Much better rate performances are observed for LTO@C particles than the un-coated LTO particles. The discharge specific capacity of the typical LTO@C sample is about 165.5 mAh g−1 at 0.1 C and 147.7 mAh g−1 at 20 C. The discharge specific capacity still keeps at 133.6 mAh g−1 after 200 cycles. The results demonstrate that the presence of carbon shell on the surface of TiO2 particles can prevent the particle agglomeration and limit the growth of lithium titanate grains within the space of carbon shell, and finally generate monodisperse un-aggregated morphology which can increase the contact area between the active material and the electrolyte. Furthermore, the uniform carbon shell can establish a conductive network to improve the overall electronic conductivity, which is beneficial to the improvement of the rate performances of LTO anodes for the applications of lithium-ion batteries.

The synergistic effect of P-doping and carbon coating for boosting electrochemical performance of TiO2 nanospheres for sodium-ion batteries

P-doping is an effective way to modulate the electronic structure and improve the Na+ diffusion kinetics of TiO2, enabling enhanced electrochemical performance. However, it is a challenge to prepare TiO2 with a high P-doping concentration starting from TiO2 in a crystalline state. In this work, we design a novel two-step route for constructing a carbon-coated anatase P-doping TiO2 nanospheres (denote as (P-AnTSS)@NC) with high P-doping concentration, by utilizing amorphous TiO2 nanospheres with the ultra-high specific area as P-doping precursor firstly, and followed by carbon coating treatment. Experimental results demonstrate that P is successfully doped into the crystal lattice and carbon layer is well coated on the surface of TiO2, with P-doping and carbon-coating contents of ~13.5 wt% and 10.4 wt%, respectively, which results in the enhanced pseudocapacitive behavior as well as favorable Na+ and electron transferring kinetics. The (P-AnTSS)@NC sample shows excellent rate and cycle performance, exhibiting specific capacities of 177 and 115 mAh/g at 0.1 and 1.0 A/g after 150 and 2000 cycles, respectively.

Carbon-coated Single-phase Ti4O7 Nanoparticles as Electrocatalyst Support

The unique structure of Magnéli phases TiOx renders them effective for the electrochemical applications. This work demonstrates a synthesis of carbon-coated Magnéli phases TiOx (TiOx@C) nanoparticles from 3-aminophenol and rutile titania (TiO2) nanoparticles as a support for platinum (Pt) electrocatalyst. 3-aminophenol was polymerized and carbonized on the surface of TiO2 nanoparticles respectively in a microwave hydrothermal reactor and a tubular furnace. Reduction of the carbon-coated TiO2 (TiO2@C) into TiOx@C was performed in hydrogen atmosphere at 800-1050 °C. The carbon coating effectively prevented TiO2 nanoparticles from sintering, resulted in TiOx@C sizes from 50 to 100 nm. Single-phase Ti4O7 core, which has the highest theoretical electrical conductivity among the Magnéli phases, was obtained from reduction of TiO2@C at 1000 °C. for 10 min C/Ti4O7-supported Pt exhibited an electrochemical surface area of 46 m2 mgPt-1 at 15% Pt loading, slightly higher than that reported for commercial TKK electrocatalyst with 20% Pt loading (44.13 m2 mgPt-1).

Facile synthesis of uniform N-doped carbon-coated TiO2 hollow spheres with enhanced lithium storage performance.

Great efforts, such as nano-structuring and carbon coating, have been devoted to addressing the poor rate performance of TiO2 anodes in lithium ion batteries, which is mainly caused by sluggish Li ion diffusion and poor electrical conductivity of the bulk material. However, the complicated fabrication processes make most of these strategies much low practical significance. Herein, a scalable and facile strategy based on sacrificial template-accelerated hydrolysis and polydopamine coating is proposed to manufacture uniform N-doped carbon-coated TiO2 hollow spheres. The nanostructured hollow structure can shorten the path of Li+ insertion/extraction in the electrode material. More importantly, the uniform carbon layer can improve the electronic conductivity of TiO2 during long-term cycling. Thus, a reversible capacity can be obtained of as high as 390.2 mA h g-1 at a current density of 0.1 A g-1. Furthermore, a high capacity of 166.3 mA h g-1 after 2000 cycles at 5.0 A g-1 shows that the carbon-coated TiO2 hollow spheres deliver good capacity retention and cycling performance.

Self-Driven Reactive Oxygen Species Generation via Interfacial Oxygen Vacancies on Carbon-Coated TiO2-x with Versatile Applications.

The effective activation and utilization of O2 have always been the focus of scientists because of its wide applications in catalysis, organic synthesis, life and medical science. Here, a novel method for activating O2 spontaneously via interfacial oxygen vacancies on carbon-coated TiO2-x to generate reactive oxygen species (ROS) with versatile applications is reported. The interfacial oxygen vacancies can be stabilized by the carbon layer and hold its intrinsic properties for spontaneous oxygen activation without light irradiation, while common surface oxygen vacancies on TiO2-x are always consumed by the capture of H2O to form the surface hydroxyls. Thus, O2 absorbed at the interface of carbon and TiO2-x can be directly activated into singlet oxygen (1O2) or superoxide radicals (·O2-), confirmed both experimentally and theoretically. These reactive oxygen species exhibit excellent performance in oxidation reactions and inhibition of MCF-7 cancer cells, providing new insight into the effective utilization of O2 via oxygen vacancies on metal oxides.