Engineering S-scheme Ag2CO3/g-c3N4 heterojunctions sonochemically to eradicate Rhodamine B dye under solar irradiation

Constructing 3D flower-like S-scheme N-Bi2O2CO3/g-C3N4 heterojunction with enhanced photocatalytic performance

Mineral processing wastewater contains a lot of organic matter and heavy metal ions, and poor self-degradation ability makes it a key treatment object in environmental treatment. Photocatalysis is a promising technology to efficiently mineralize refractory contaminants from wastewater. In this work, 3D flower-like S-scheme N-Bi2O2CO3/g-C3N4 heterostructures were successfully constructed by hydrothermal method with the auxiliary of ionic liquids. The photocatalytic experiments show that the catalytic activity of heterojunction photocatalysts was significantly higher than that of bare g-C3N4 and N-Bi2O2CO3 for the degradation of two pollutants. NBOC/CN-2 shows the highest photocatalytic performance, and the degradation efficiency of sodium isobutyl xanthate (SIBX) on NBOC/CN-2 is 1.85 and 3 times that of bare g-C3N4 and Bi2O2CO3, respectively. The degradation efficiency of m-Cresol on NBOC/CN-2 is 8.34 and 6.93 times that of bare g-C3N4 and N-Bi2O2CO3, respectively. This significantly enhanced photocatalytic activity is attributed to the formation of flower-like heterojunctions, which can greatly increase the specific surface area and facilitate the separation and migration of photogenerated carriers. Total organic carbon (TOC) experiment proves that the two pollutants are effectively mineralized under the action of the prepared photocatalyst. The degradation path of m-Cresol degradation products was inferred based on the ion fragments. The capture experiment and Nitro-blue tetrazolium (NBT)-•O2- measurement show that superoxide radical plays a major role in photocatalytic degradation. The outstanding stability of the prepared flower-like heterojunction samples was examined by cyclic experiments. The S-scheme charge transfer mechanism has been proposed to explain the boosted activity of the flower-like heterojunction photocatalyst. This work provides a new idea for the design of efficient and stable g-C3N4-based photocatalyst for the photocatalytic degradation of refractory wastewater.

Advances in ultrasound-assisted synthesis of photocatalysts and sonophotocatalytic processes: A review

Water pollution and the global energy crisis are two significant challenges that the world is facing today. Ultrasound-assisted synthesis offers a simple, versatile, and green synthetic tool for nanostructured materials that are often unavailable by traditional synthesis. Furthermore, the integration of ultrasound and photocatalysis has recently received considerable interest due to its potential for environmental remediation as a low-cost, efficient, and environmentally friendly technique. The underlying principles and mechanisms of sonophotocatalysis, including enhanced mass transfer, improved catalyst-pollutant interaction, and reactive species production have been discussed. Various organic pollutants as dyes, pharmaceuticals, pesticides, and emerging organic pollutants are targeted based on their improved sonophotocatalytic degradation efficiency. Additionally, the important factors affecting sonophotocatalytic processes and the advantages and challenges associated with these processes are discussed. Overall, this review provides a comprehensive understanding of sono-assisted synthesis and photocatalytic degradation of organic pollutants and prospects for progress in this field.

Potato-on-rod like of Z-scheme plasmon Ag2CrO4-Ag2Mo2O7 heterojunction nanophotocatalyst with high stability and accelerated photo-degradation evolution of organic contaminants

The shocking increase of resistant dye pollutants in the environment and their harmful effects has become a potential threat to the ecosystem. In the current work, the novel and highly efficient potato-on-rod-like Z-scheme plasmon Ag2CrO4-Ag2Mo2O7 heterojunction nano-photocatalyst was synthesized by precipitation method to photodegrade different organic dyes under artificial sunlight. The required analysises were carried out to characterize nanophotocatalysts. FESEM and TEM results showed the placement way of potato-like Ag2CrO4 between/on rod-like Ag2Mo2O7 which was leading to suitable structure and surface morphology. Besides, the morphology observations released the meso-/macroporous potato-on-rod like architecture self-assembled by nanoparticles. DRS analysis also confirmed two band gap energies of 2.55 and 1.72 eV in Ag2CrO4-Ag2Mo2O7 (3:1) resulting from forming a heterojunction structure and the plasmon Ag. Ag2CrO4-Ag2Mo2O7 (3:1) nanophotocatalyst exhibited the most remarkable activity in the photodegradation of 10 mg/L 2-naphthol orange (97.8%), 10 mg/L rhodamine B (99.7%), 10 mg/L crystal violet (98.9%), and 10 mg/L methyl orange (56.1%) with a catalyst dosage of 0.1 gr for about 90 min. The appropriate energy band gap, the formation of the heterostructure, the presence of meso (0.0038 cm3/g) and macro (0.0044 cm3/g) holes, and pore diameter at about 17.2 nm based on BET-BJH analysis that facilitated the penetration of pollutant molecules, increased pollutant adsorption and demonstrated stunning capability of efficient light harvesting, the reason was electron-hole pairs recombination rate reduction. Moreover, the fabricated samples showed tremendous catalyst constancy and reusability even after the fourth run. Results have shown the remarkable photocatalytic activity under visible light and provide an environment-friendly and green strategy to overcome the challenges of organic pollutants present in aqueous solutions.