Green preparation of in-situ oxidized TiO2/Ti3C2 heterostructure for photocatalytic hydrogen production

Laser-Treated MXene as an Electrochemical Agent to Boost Properties of Semitransparent Photoelectrode Based on Titania Nanotubes

In this study, Ti3C2Tx underwent laser treatment to reshape it, resulting in the formation of a TiO2/Ti3C2Tx heterojunction. The interaction with laser light induced the formation of spherical TiO2 composed of an anatase-rutile phase on the Ti3C2Tx surface. Such a heterostructure was loaded over a titania nanotube (TNT) layer, and the surface area was enhanced through immersion in a TiCl4 solution followed by thermal treatment. Consequently, the photon-to-electron conversion efficiency exhibits a 10-fold increase as compared to bare TNT. Moreover, for the sample produced with optimized conditions, five times higher photoactivity is observed in comparison to bare TNT. It was shown that under visible light irradiation the most photoactive heterojunction based on the tubular layer reveals a substantial drop in the charge transfer resistance of about 32% with respect to the dark condition. This can be attributed to the narrower band gaps of the modified material and improvement of the separation efficiency of the photogenerated electron-hole pairs. Overall results suggest that this investigation underscores TiO2/Ti3C2Tx as a promising noble-metal-free material that enhances both the electrochemical and photoelectrochemical performances of electrode materials based on TNT that can be further used in light-harvesting applications.

A H2O2 Oxidation Approach to Ti3C2/TiO2 for Efficient Photocatalytic Removal of Distinct Organic Pollutants in Water

To develop versatile photocatalysts for efficient degradation of distinct organic pollutants in water is a continuous pursuit in environment remediation. Herein, we directly oxidize Ti3C2 MXene with hydrogen peroxide to produce C-doped anatase TiO2 nanowires with aggregates maintaining a layered architecture of the MXene. The Ti3C2 MXene provides a titanium source for TiO2, a carbon source for in situ C-doping, and templates for nanowire aggregates. Under UV light illumination, the optimized Ti3C2/TiO2 exhibits a reaction rate constant 1.5 times that of the benchmark P25 TiO2 nanoparticles, toward photocatalytic degradations of trace phenol in water. The mechanism study suggests that photogenerated holes play key roles on the phenol degradation, either directly oxidizing phenol molecules or in an indirect way through oxidizing first the surface hydroxyl groups. The unreacted Ti3C2 MXene, although with trace amounts, is supposed to facilitate electron transfer, which inhibits charge recombination. The unique nanostructure of layered aggregates of nanowires, abundant surface oxygen vacancies arising from the carbon doping, and probably the Ti3C2/TiO2 heterojunction guarantee the high photocatalytic efficiency toward removals of organic pollutants in water. The photocatalyst also exhibits an activity superior to, or at least comparable to, the benchmark P25 TiO2 toward photodegradations for typical persistent organic pollutants of phenol, dye molecule of rhodamine B, antibiotic of tetracycline, pharmaceutical wastewater of ofloxacin, and pesticide of N,N-dimethylformamide, when evaluated in total organic carbon removal.

TiO2nanorod arrays/Ti3C2TxMXene nanosheet composites with efficient photocatalytic activity

Semiconductor photocatalysis holds significant promise in addressing both environmental and energy challenges. However, a major hurdle in photocatalytic processes remains the efficient separation of photoinduced charge carriers. In this study, TiO2nanorod arrays were employed by glancing angle deposition technique, onto which Ti3C2TxMXene was deposited through a spin-coating process. This hybrid approach aims to amplify the photocatalytic efficacy of TiO2nanorod arrays. Through photocurrent efficiency characterization testing, an optimal loading of TiO2/Ti3C2Txcomposites is identified. Remarkably, this composite exhibits a 40% increase in photocurrent density in comparison to pristine TiO2. This enhancement is attributed to the exceptional electrical conductivity and expansive specific surface area inherent to Ti3C2TxMXene. These attributes facilitate swift transport of photoinduced electrons, consequently refining the separation and migration of electron-hole pairs. The synergistic TiO2/Ti3C2Txcomposite showcases its potential across various domains including photoelectrochemical water splitting and diverse photocatalytic devices. As such, this composite material stands as a novel and promising entity for advancing photocatalytic applications. This study can offer an innovative approach for designing simple and efficient photocatalytic materials composed of MXene co-catalysts and TiO2for efficient water electrolysis on semiconductors.

Synthesis of AgBr/Ti3C2@TiO2 ternary composite for photocatalytic dehydrogenation of 1,4-dihydropyridine and photocatalytic degradation of tetracycline hydrochloride

In this work, AgBr/Ti₃C₂@TiO₂ ternary composite photocatalyst was prepared by a solvothermal and precipitation method with the aims of introducing Ti₃C₂ as a cocatalyst and TiO₂ as a compositing semiconductor. The crystal structure, morphology, elemental state, functional groups and photoelectrochemical properties were studied by XRD, SEM, TEM, XPS, FI-IR and EIS. The photocatalytic performances of the composites were investigated by the photodehydrogenation of diethyl 1,4-dihydro-2,6-dimethyl-3,5-pyridinedicarboxylate (1,4-DHP) and the photodegradation of tetracycline hydrochloride (TCH) under visible light irradiation (λ > 400 nm). The AgBr/Ti₃C₂@TiO₂ composite photocatalyst showed enhanced photocatalytic performance in both photocatalytic reactions. The photocatalytic activity of the composite photocatalyst is dependent on the proportional content of Ti₃C₂@TiO₂. With optimized Ti₃C₂@TiO₂ proportion, the photocatalytic ability of the AgBr/Ti₃C₂@TiO₂ composite was 24.5 times as high as that of Ti₃C₂@TiO₂ for photodehydrogenation of 1,4-DHP and 1.9 times as high as that of pure AgBr for photodegradation of TCH. The enhanced photocatalytic performance of the AgBr/Ti₃C₂@TiO₂ composite should be due to the formation of a p-n heterojunction structure between AgBr and Ti₃C₂@TiO₂ and the excellent electronic properties of Ti₃C₂, which enhanced the visible light absorption capacity, lowered the internal resistance, speeded up the charge transfer and reduced the recombination efficiency of photo-generated carriers. Mechanism studies showed that superoxide free radical (˙O₂^-) was the main active species. In addition, the composite photocatalyst also displayed good stability, indicating its reutilization in practical application.

Simple preparation of in-situ oxidized titanium carbide MXene for photocatalytic degradation of catechol

Photocatalytic system has been widely applied to treat the highly toxic and refractory aromatics sewage water pollution problem. However, developing highly active and excellent durability photocatalysts is always the long-term...