Controllable Fabrication of Heterogeneous p-TiO2 QDs@g-C3N4 p-n Junction for Efficient Photocatalysis

The Collision between g-C3 N4 and QDs in the Fields of Energy and Environment: Synergistic Effects for Efficient Photocatalysis

Recently, graphitic carbon nitride (g-C₃ N₄ ) has attracted increasing interest due to its visible light absorption, suitable energy band structure, and excellent stability. However, low specific surface area, finite visible light response range (<460 nm), and rapid photogenerated electron-hole (e^- -h⁺ ) pairs recombination of the pristine g-C₃ N₄ limit its practical applications. The small size of quantum dots (QDs) endows the properties of abundant active sites, wide absorption spectrum, and adjustable bandgap, but inevitable aggregation. Studies have confirmed that the integration of g-C₃ N₄ and QDs not only overcomes these limitations of individual component, but also successfully inherits each advantage. Encouraged by these advantages, the synthetic strategies and the fundamental of QDs/g-C₃ N₄ composites are briefly elaborated in this review. Particularly, the synergistic effects of QDs/g-C₃ N₄ composites are analyzed comprehensively, including the enhancement of the photocatalytic performance and the avoidance of aggregation. Then, the photocatalytic applications of QDs/g-C₃ N₄ composites in the fields of environment and energy are described and further combined with DFT calculation to further reveal the reaction mechanisms. Moreover, the stability and reusability of QDs/g-C₃ N₄ composites are analyzed. Finally, the future development of these composites and the solution of existing problems are prospected.

Fabrication and characterization of a TiBs@MCN cable-like photocatalyst with high photocatalytic performance under visible light irradiation

A cable-like photocatalyst, TiBs@MCN, with a larger specific surface area and higher visible-light photocatalytic activity, is successfully fabricated by an in situ hydrothermal self-assembly approach.

Surface modification to control the secondary pollution of photocatalytic nitric oxide removal over monolithic protonated g-C3N4/graphene oxide aerogel

Recently, photocatalytic NO_x treatment has attracted great attention on account of the use of environmental-friendly and tremendous energy source. However, the difficult recovery of most reported powdery photocatalysts and the high generation rate of toxic NO₂ byproduct limit its application. Here, we designed a novel monolithic protonated g-C₃N₄/graphene oxide aerogel through a direct frozen-drying method. A remarkable surface electric charge change of negative g-C₃N₄ to positive protonated g-C₃N₄ can be observed after the protonating treatment, which connects with negative graphene oxide nanosheets through the formation of strong electrostatic self-assembly to accelerate the photogenerated charge carriers transfer. Graphene oxide aerogel acts as a monolithic substrate, which provides abundant porous structure, enhanced visible-light absorption, and electrons transport pathway to improve photocatalytic activity. Importantly, the introduction of H atoms on the N atoms of p-C₃N₄ promotes the activation of oxygen atoms, thus improving the oxidization of NO₂ to nitrate. As a result, protonated g-C₃N₄/graphene oxide aerogel reveals an excellent NO removal ratio (46.1%) and low NO₂ generation (2.4%), demonstrating its excellent promising for air pollution purification. Our current work affords novel innovative insight for the construction of monolithic photocatalysts to control the secondary pollution for environmental remediation.

Editorial: Special Issue on “Emerging Trends in TiO2 Photocatalysis and Applications”

It is not an exaggerated fact that the semiconductor titanium dioxide (TiO2) has been evolved as a prototypical material to understand the photocatalytic process and has been demonstrated for various photocatalytic applications such as pollutants degradation, water splitting, heavy metal reduction, CO2 conversion, N2 fixation, bacterial disinfection, etc [...]

Enhanced photocatalytic activity of anatase by the rational modification of the {001} facets with Fe(iii) ions

Fe(iii) ion-modified TiO₂ exhibits the highest reaction efficiency for the decomposition of dye molecules and p-chlorophenol due to electron-trapping centers.

Effect of Heterointerface on NO2 Sensing Properties of In-Situ Formed TiO2 QDs-Decorated NiO Nanosheets

In this work, TiO₂ QDs-modified NiO nanosheets were employed to improve the room temperature NO₂ sensing properties of NiO. The gas sensing studies showed that the response of nanocomposites with the optimal ratio to 60 ppm NO₂ was nearly 10 times larger than that of bare NiO, exhibiting a potential application in gas sensing. Considering the commonly reported immature mechanism that the effective charge transfer between two phases contributes to an enhanced sensitivity, the QDs sensitization mechanism was further detailed by designing a series of contrast experiments. First, the important role of the QDs size effect was revealed by comparing the little enhanced sensitivity of TiO₂ particle-modified NiO with the largely enhanced sensitivity of TiO₂ QDs-NiO. Second, and more importantly, direct evidence of the heterointerface charge transfer efficiency was detailed by the extracted interface bond (Ti-O-Ni) using XPS peak fitting. This work can thus provide guidelines to design more QDs-modified nanocomposites with higher sensitivity for practical applications.