Oxygen Vacancy Enhanced Photoreduction Cr(VI) on Few-Layers BiOBr Nanosheets

Comprehensive Insights into the Family of Atomically Thin 2D-Materials for Diverse Photocatalytic Applications

2D materials with their fascinating physiochemical, structural, and electronic properties have attracted researchers and have been used for a variety of applications such as electrocatalysis, photocatalysis, energy storage, magnetoresistance, and sensing. In recent times, 2D materials have gained great momentum in the spectrum of photocatalytic applications such as pollutant degradation, water splitting, CO2 reduction, NH3 production, microbial disinfection, and heavy metal reduction, thanks to their superior properties including visible light responsive band gap, improved charge separation and electron mobility, suppressed charge recombination and high surface reactive sites, and thus enhance the photocatalytic properties rationally as compared to 3D and other low-dimensional materials. In this context, this review spot-lights the family of various 2D materials, their properties and their 2D structure-induced photocatalytic mechanisms while giving an overview on their synthesis methods along with a detailed discussion on their diverse photocatalytic applications. Furthermore, the challenges and the future opportunities are also presented related to the future developments and advancements of 2D materials for the large-scale real-time photocatalytic applications.

Cocatalyst loaded Al-SrTiO3 cubes for Congo red dye photo-degradation under wide range of light

The continued pollution, waste, and unequal distribution of the limited amount of fresh water on earth are pushing the world into water scarcity crisis. Consequently, development of revolutionary, cost-effective, and efficient techniques for water purification is essential. Herein, molten flux method was used for the preparation of micro-sized Al-doped SrTiO₃ photocatalyst loaded with RhCr₂O₃ and CoOOH cocatalysts via simple impregnation method for the photo-assisted degradation of Congo red dye under UV and visible irradiation compared with P25 standard photocatalyst. In addition, photoelectrochemical analysis was conducted to reveal the separation and transfer efficiency of the photogenerated e^-/h⁺ pairs playing the key role in photocatalysis. SEM and TEM analyses revealed that both P25 and the pristine SrTiO₃ have spherical shapes, while Al-doped SrTiO₃ and the sample loaded with cocatalysts have cubic shapes with a relatively higher particle size reaching 145 nm. In addition, the lowest bandgap is due to Al⁺³ ion doping and excessive surface oxygen vacancies, as confirmed by both UV-Vis diffuse-reflectance and XPS analyses. The loading of the cocatalysts resulted in a change in the bandgap from n-type (pristine SrTiO₃ and Al-SrTiO₃) into p-type (cocatalyst loaded sample) as exhibited by Mott-Schottky plots. Besides, the cocatalyst-loaded sample exhibited good performance stability after 5 cycles of the photocatalytic removal of Congo red dye. OH^· radical was the primary species responsible for CR degradation as confirmed by experiments with radical scavengers. The observed performance of the prepared samples under both UV and visible light could foster the ongoing efforts towards more efficient photocatalysts for water purification.

Enhanced photocatalytic and antimicrobial performance of a multifunctional Cu-loaded nanocomposite under UV light: theoretical and experimental study

Due to modern industrialization and population growth, access to clean water has become a global challenge. In this study, a metal-semiconductor heterojunction was constructed between Cu NPs and the Co_0.5Ni_0.5Fe₂O₄/SiO₂/TiO₂ composite matrix for the photodegradation of potassium permanganate, hexavalent chromium Cr(VI) and p-nitroaniline (pNA) under UV light. In addition, the electronic and adsorption properties after Cu loading were evaluated using density functional theory (DFT) calculations. Moreover, the antimicrobial properties of the prepared samples toward pathogenic bacteria and unicellular fungi were investigated. Photocatalytic measurements show the outstanding efficiency of the Cu-loaded nanocomposite compared to that of bare Cu NPs and the composite matrix. Degradation efficiencies of 44% after 80 min, 100% after 60 min, and 65% after 90 min were obtained against potassium permanganate, Cr(VI), and pNA, respectively. Similarly, the antimicrobial evaluation showed high ZOI, lower MIC, higher protein leakage amount, and cell lysis of nearly all microbes treated with the Cu-loaded nanocomposite.

Photocatalysis: Activity of Nanomaterials

Photocatalytic processes have shown great potential as a low-cost, green-chemical, and sustainable technology able to address energy and environmental issues [...]

Efficient reduction of Cr(VI) by a BMO/Bi2S3 heterojunction via synergistic adsorption and photocatalysis under visible light

The development of efficient visible light driven photocatalyst is the premise of the progress of photocatalytic technology. In this paper, a well-designed orthorhombic Bi₂MoO₆/Bi₂S₃ (BMO/Bi₂S₃) composite was obtained by a two-step fabrication route. Using MoO₃ nanobelt as a sacrificial template, BMO nanosheet-based framework was prepared by refluxing process. Through anion exchange reaction of the synthesized BMO to introduce Bi₂S₃ nanosheets, and BMO/Bi₂S₃ heterojunction was successfully constructed. Simultaneously, the Bi₂S₃ loading percentage of BMO/Bi₂S₃ was controlled by tuning the anion exchange time. The intimate interfacial contact between the BMO framework and Bi₂S₃ nanosheets endows the nanocomposites with high adsorption and photocatalytic removal of Cr(VI). Photocatalytic tests show that BMO/Bi₂S₃-1 composite possess the highest activity with 100 % removal rate of Cr(VI) in 15 min. The dramatically enhanced adsorption and photocatalytic capacity of BMO/Bi₂S₃ photocatalysts can be ascribed to the frame structure, large surface area and numerous nanochannels. In addition, the BMO/Bi₂S₃ photocatalyst is highly stable during the reaction and can be used repeatedly. These features indicate that the BMO/Bi₂S₃ composite could be used for environmental remediation and wastewater treatment.