Composite nanoarchitectonics with TiO2 nanocrystals and superior thin Ti3C2Tx nanosheets towards efficient NO removal

Tungsten Oxide/g-C3N4 Heterostructures: Composition, Structure, and Photocatalytic Applications

The construction of heterostructures promotes extending the light adsorption range of graphitic carbon nitride (g-C3N4) materials, improving the photogenerated charge carrier separation/transfer efficiency for attaining much enhanced performances. Because defective tungsten oxide (WOx) materials possess rich composition/morphology and an extended light response in the near-infrared region, WOx is a quite popular nanocomponent for modifying g-C3N4, forming heterostructures that can be used for various photocatalytic applications involving water splitting, CO2 reduction, NOx removal, H2O2 generation, and related chemical to fuel conversion reactions. In this review, important aspects of WOx/g-C3N4 heterostructure photocatalysts are reviewed to provide paradigms for composition adjustment, structural design, and photocatalytic applications of these materials. The WOx growth control in amorphous and crystalline g-C3N4, adjustment on heterostructure types (e.g., type II and Z-scheme), and the catalytic performances of the composite system are also discussed in detail. Moreover, the effects of synthetic methodologies and preparation parameters on the formation of two-dimensional layered heterostructures are discussed to provide inspiration for the construction of state-of-the-art WOx/g-C3N4 heterostructures that can be utilized for photoredox reactions. The challenges and prospects of the heterostructure formation and the photocatalytic applications of the heterostructures in future research are also summarized.

Titanium Carbide (Ti3C2Tx) MXene for Sequestration of Aquatic Pollutants

The rapid expansion of industrialization has resulted in the release of multiple ecological contaminants in gaseous, liquid, and solid forms, which pose significant environmental risks to many different ecosystems. The efficient and cost-effective removal of these environmental pollutants has attracted global attention. This growing concern has prompted the synthesis and optimization of nanomaterials and their application as potential pollutant removal. In this context, MXene is considered an outstanding photocatalytic candidate due to its unique physicochemical and mechanical properties, which include high specific surface area, physiological compatibility, and robust electrodynamics. This review highlights recent advances in shaping titanium carbide (Ti3C2Tx) MXenes, emphasizing the importance of termination groups to boost photoactivity and product selectivity, with a primary focus on engineering aspects. First, a broad overview of Ti3C2Tx MXene is provided, delving into its catalytic properties and the formation of surface termination groups to establish a comprehensive understanding of its fundamental catalytic structure. Subsequently, the effects of engineering the morphology of Ti3C2Tx MXene into different structures, such as two-dimensional (2D) accordion-like forms, monolayers, hierarchies, quantum dots, and nanotubes. Finally, a concise overview of the removal of different environmental pollutants is presented, and the forthcoming challenges, along with their prospective outlooks, are delineated.

Accelerating carrier separation to boost the photocatalytic CO2 reduction performance of ternary heterojunction Ag-Ti3C2Tx/ZnO catalysts

Developing low-cost and efficient photocatalyst/co-catalyst systems that promote CO2 reduction remains a challenge. In this work, Ag-Ti3C2Tx composites were made using a self-reduction technique, and unique Ag-Ti3C2Tx/ZnO ternary heterojunction structure photocatalysts were created using an electrostatic self-assembly process. The photocatalyst's close-contact heterogeneous interface increases photogenerated carrier migration efficiency. The combination of Ti3C2Tx and Ag improves the adsorption active sites and reaction centers for ZnO, making it a key site for CO2 adsorption and activation. The best photocatalysts had CO and CH4 reduction efficiencies of 11.985 and 0.768 μmol g-1 h-1, respectively. The CO2 conversion was 3.35 times better than that of pure ZnO, which demonstrated remarkable stability even after four cycle trials with no sacrificial agent. Furthermore, in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) and valence band spectroscopy were utilized to propose the photocatalytic reaction mechanism and electron transfer channels of the Ag-Ti3C2Tx/ZnO system, confirming that CHO* and CO* are the important intermediates in the generation of CH4 and CO. This study introduces a novel method for the development of new and efficient photocatalysts and reveals that Ti3C2Tx MXene is a viable co-catalyst for applications.

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.

Multifunctional MnFe2O4/TiO2/Ti3C2Tx composites based on in-situ grown TiO2 for efficient microwave absorption, high hydrophobicity, and heat dissipation properties

Despite the fact that the 2D structure Ti3C2Tx with abundant defects and functional groups contributes to the high microwave absorption (MA) performance, it is difficulty to improve the strength and bandwidth by pursuing higher conductivity or loading more groups due to the limitation of intrinsic properties. Therefore, it is important to ingeniously design efficient Ti3C2Tx based MA composites assembling the features of abundant surface groups, good dispersibility, multiple composition, and precise structure. Inspired by the fact that Ti3C2Tx contains thermodynamically metastable marginal Ti atoms, TiO2 nanoparticles can be grown in-situ on Ti3C2Tx nanosheets uniformly and increase the spacing of Ti3C2Tx layers, and then MnFe2O4 nanoparticles are introduced into the layers of Ti3C2Tx by electrostatic self-assembly method for optimized impedance matching. This designed hierarchical MnFe2O4/TiO2/Ti3C2Tx composites shows excellent MA performance, and the minimum reflection loss (RLmin) reaches -46.91 dB with a thickness of 2.5 mm at frequency of 10.4 GHz. The high MA performance mainly comes from the enhanced interfacial polarization induced by edges location and interface region among TiO2, MnFe2O4, and Ti3C2Tx. In addition, the conduction loss existed in the interior untreated Ti3C2Tx, the dielectric loss generated by multiple composition, the multiple scattering from improved large surface specific area all contribute to the excellent MA performance. Meanwhile, the simple preparation process and good stability storage at room temperature under air atmosphere of the MnFe2O4/TiO2/Ti3C2Tx composites promote its exploration on practical use, and the lab-gown cloth coated with MnFe2O4/TiO2/Ti3C2Tx composites shows better electromagnetic shielding properties, hydrophobicity, and heat transfer ability than pure fabric, showing the potential for practical application.