Polyoxometalate@g-C3N4 nanocomposite for enhancing visible light photoelectrocatalytic performance

Design strategies and mechanisms of g-C3N4-based photoanodes for photoelectrocatalytic degradation of organic pollutants in water

Emerging photoelectrocatalytic (PEC) systems integrate the advantages of photocatalysis and electrocatalysis and are considered as a promising technology for solving the global organic pollution problem in water environments. Among the photoelectrocatalytic materials applied for organic pollutant degradation, graphitic carbon nitride (CN) has the combined advantages of environmental compatibility, stability, low cost, and visible light response. However, pristine CN has disadvantages such as low specific surface area, low electrical conductivity, and high charge complexation rate, and how to improve the degradation efficiency of PEC reaction and the mineralization rate of organic matter is the main problem faced in this field. Therefore, this paper reviews the progress of various functionalized CN used for PEC reaction in recent years, and the degradation efficiency of these CN-based materials is critically evaluated. First, the basic principles of PEC degradation of organic pollutants are outlined. Then, engineering strategies to enhance the PEC activity of CN (including morphology control, elemental doping, and heterojunction construction) are focused on, and the structure-activity relationships between these engineering strategies and PEC activity are discussed. In addition, the important role of influencing factors on the PEC system is summarized in terms of mechanism, to provide guidance for the subsequent research. Finally, suggestions and perspectives are provided for the preparation of efficient and stable CN-based photoelectrocatalysts for practical wastewater treatment applications.

Recent Progress in Doped g-C3N4 Photocatalyst for Solar Water Splitting: A Review

Graphitic carbon nitride (g-C₃N₄) photocatalysis for water splitting is harvested as a fascinating way for addressing the global energy crisis. At present, numerous research subjects have been achieved to design and develop g-C₃N₄ photocatalysis, and the photocatalytic system still suffers from low efficiency that is far from practical applications. Here, there is an inspiring review on the latest progress of the doping strategies to modify g-C₃N₄ for enhancing the efficiency of photocatalytic water splitting, including non-metal doping, metal doping, and molecular doping. Finally, the review concludes a summary and highlights some perspectives on the challenges and future research of g-C₃N₄ photocatalysts.

Polyoxometalate Modified by Zeolite Imidazole Framework for the pH-Responsive Electrodynamic/Chemodynamic Therapy

Electrodynamic therapy (EDT) and chemodynamic therapy (CDT) have the potential for future tumor treatment; however, their underlying applications are greatly hindered owing to their inherent drawbacks. The combination of EDT and CDT has been considered to be an effective way to maximize the superiorities of these two ROS-based methodologies. However, the development of novel nanomaterials with "one-for-all" functions still remains a big challenge. In this work, the polyoxometalate nanoparticles (NPs) were decorated using the zeolite imidazole framework (POM@ZIF-8) in order to integrate the EDT with CDT. The resulting POM@ZIF-8 NPs can effectively induce the generation of reactive oxygen species (ROS) via a catalytic reaction on the surface of POM NPs induced by an electric field (E). At the same time, POM@ZIF-8 NPs can catalyze the intracellular H₂O₂ into ROS via a Fenton-like reaction, thereby achieving the combination of EDT and CDT. Besides, since ZIF-8 is acid-responsive, it can protect normal tissues and avoid side effects. Of great note is that the cytotoxicity and the apoptosis rate of the POM@ZIF-8+E group (80%) were found to be significantly higher than that of the E group (55%). As a result, a high tumor inhibition phenomenon can be observed both in vitro and in vivo. The present study thus provides an alternative concept for combinational therapeutic modality with exceptional efficacy.

Insight into the activity of TiO2@nitrogen-doped hollow carbon spheres supported on g-C3N4 for robust photocatalytic performance

Designing an advance nanostructure semiconductor is an efficient strategy to promote the charge separation and thus improve the photocatalytic activity. Herein, a relatively high recombination rate of electron-hole pairs and low specific surface area of g-C₃N₄ (GCN) were subjected to the surface deposition of the core shell nanoparticles composed of nitrogen doped hollow carbon spheres (N-HCSs) as the supporting scaffold and TiO₂ nanoparticles as the photoactive layer. The ternary composites with different TiO₂@N-HCS content were prepared through a simplified nanocasting method followed by the two consecutive hydrothermal process. The effects of nitrogen doping in carbon framework, and nanoparticles amount were evaluated on the photocatalytic ability through the photodegradation of tetracycline (TC) molecules under the visible light irradiation. At the optimum content of core shell nanoparticles (7 wt%), the solar-driven TC photocatalytic degradation for ternary composite was approximately 85%, which was much better (about three times) than that of the pure GCN. More interestingly, the experimental results revealed that doping of nitrogen atoms has a positive role on the charge separation and the resulting photocatalytic efficiency. The employed hollow carbon spheres here play three important roles: (1) providing a substrate to uniformly dispersion of TiO₂ nanoparticles without any aggregation; (2) reducing the combination of charge carriers and improving the separation of photoinduced carriers; (3) formation of larger surface area and more active sites on the photocatalyst surface. Furthermore, the underlying photocatalytic degradation mechanism was introduced by the controlled experiments using photoluminescent and radical scavenger tests.