Synergistic mechanisms of carbon-based materials for VOCs photocatalytic degradation: A critical review

With the rapid expansion of human activities, there has been a significant increase in the release of volatile organic compounds (VOCs) from factories and interior decoration materials, posing a substantial risk to the surrounding ecosystem and human health. Photocatalysis technology based on semiconductors has emerged as a promising solution for mitigating atmospheric pollution and indoor air quality concerns. However, single semiconductors encounter several challenges when it comes to VOC photodegradation, including issues like the weak adsorption capacity for VOC molecules, insufficient surface-active sites, and limited light utilization. In recent decades, carbon-based materials have gained considerable interest in photodegrading VOCs owing to their strong adsorption capacity, electrical conductivity, broad light absorption range, and tunable surface characteristics. The incorporation of carbon materials can enhance the photodegradation efficiency of VOCs by facilitating the transfer of VOCs from the ambient air to the surface of the photocatalysts, increasing the number of active surface sites, expanding the light absorption region, and promoting the separation of charge carriers. This review provides a comprehensive overview of the applications of carbon materials with different dimensions in enhancing the performance of semiconductors for the photocatalytic degradation of VOCs. Based on the fundamental principles of photocatalytic VOC degradation, this review explores the factors influencing the degradation performance of catalysts and elucidates the degradation mechanisms. Moreover, it summarizes a range of synthesis approaches for carbon-based photocatalysts, discussing the multiple roles played by carbon materials in these processes. In conclusion, the review offers insights into the current state of carbon-based photocatalysts and outlines the existing challenges. It also provides a perspective on the future development of these materials, highlighting the need for continued research and innovation in this field.

Recent Progress of Carbon Dots for Air Pollutants Detection and Photocatalytic Removal: Synthesis, Modifications, and Applications

Rapid industrialization has inevitably led to serious air pollution problems, thus it is urgent to develop detection and treatment technologies for qualitative and quantitative analysis and efficient removal of harmful pollutants. Notably, the employment of functional nanomaterials, in sensing and photocatalytic technologies, is promising to achieve efficient in situ detection and removal of gaseous pollutants. Among them, carbon dots (CDs) have shown significant potential due to their superior properties, such as controllable structures, easy surface modification, adjustable energy band, and excellent electron-transfer capacities. Moreover, their environmentally friendly preparation and efficient capture of solar energy provide a green option for sustainably addressing environmental problems. Here, recent advances in the rational design of CDs-based sensors and photocatalysts are highlighted. An overview of their applications in air pollutants detection and photocatalytic removal is presented, especially the diverse sensing and photocatalytic mechanisms of CDs are discussed. Finally, the challenges and perspectives are also provided, emphasizing the importance of synthetic mechanism investigation and rational design of structures.

Photocatalysis and perovskite oxide-based materials: a remedy for a clean and sustainable future

The massive use of non-renewable energy resources by humankind to fulfill their energy demands is causing severe environmental issues. Photocatalysis is considered one of the potential solutions for a clean and sustainable future because of its cleanliness, inexhaustibility, efficiency, and cost-effectiveness. Significant efforts have been made to design highly proficient photocatalyst materials for various applications such as water pollutant degradation, water splitting, CO2 reduction, and nitrogen fixation. Perovskite photocatalyst materials are gained special attention due to their exceptional properties because of their flexibility in chemical composition, structure, bandgap, oxidation states, and valence states. The current review is focused on perovskite materials and their applications in photocatalysis. Special attention has been given to the structural, stoichiometric, and compositional flexibility of perovskite photocatalyst materials. The photocatalytic activity of perovskite materials in different photocatalysis applications is also discussed. Various mechanisms involved in photocatalysis application from wastewater treatment to hydrogen production are also provided. The key objective of this review is to encapsulate the role of perovskite materials in photocatalysis along with their fundamental properties to provide valuable insight for addressing future environmental challenges.

2D/2D Bi2WO6/Protonated g-C3N4 step-scheme heterojunctions for enhancing the photodegradation of 17β-estradiol: promotional role of electrostatic interaction

A Bi2WO6/protonated g-C3N4 step-scheme heterojunction with an intimate interface though electrostatic interaction exhibited enhanced photodegradation of 17β-estradiol under visible light.

Synthesis and characterization of CuxO/Bi2O3 oxides for removal of HCHO under visible light irradiation

Cu_xO/Bi₂O₃ oxides grown on nickel foam were synthesized via an electrodeposition method to degrade indoor HCHO under visible light irradiation and fully characterized by XRD, SEM, FT-IR, and UV-Vis technologies. The characterization results showed that the Cu_xO/Bi₂O₃ oxides were successfully loaded on nickel foam and the visible light response spectrum was expanded to 740 nm. Plackett-Burman design combined with central composite design has been used to optimize factors that affect HCHO removal performance. The results demonstrated that bismuth nitrate content, polyethylene glycol 600 content, sintering time, and lactic acid concentration were the four most important factors affecting the HCHO removal performance over Cu_xO/Bi₂O₃ sample. The optimum Cu_xO/Bi₂O₃ sample could degrade 88.796% of HCHO in 300 min at the conditions of 4.28 mol/L lactic acid, 4.86% polyethylene glycol 600, 194.03 min sintering time, and 45.83 g bismuth nitrate, and the HCHO removal rate remained 82.3% after five cycles. A plausible mechanism for the degradation of HCHO under visible light irradiation was proposed. This work provides a feasible solution for removing indoor formaldehyde in the field of photocatalysis.

Efficient photocatalytic degradation of volatile organic compounds over carbon quantum dots decorated Bi2WO6 under visible light

A series of CQDs/Bi₂WO₆ (CBW) hybrid materials with different loading amounts of carbon quantum dots (CQDs) were prepared via a facile in situ hydrothermal method. As determined by multiple techniques including XRD, TEM, UV-vis, PL, TPR, and XPS, the CBW possessed expanded visible light response interval, decreased recombination rate of the photogenerated electron hole, and enhanced oxidation ability as compared with the pristine Bi₂WO₆. In addition, with different loading amounts of CQDs, the optical and electronic properties of the corresponding CBW were different. These CBW materials performed superior activities to the pristine Bi₂WO₆ in the photodegradation of VOCs under visible light, among which the CBW-2 demonstrated the best activity of almost complete degradation within only 120 min. Moreover, the CBW-2 exhibited high stability and reusability after five cycles.

Degradation of gaseous unsymmetrical dimethylhydrazine by vacuum ultraviolet coupled with MnO2

Enhanced degradation of gaseous UDMH under VUV irradiation by catalytic ozonation with MnO₂.