Controllable synthesis of TiO2 chemically bonded graphene for photocatalytic hydrogen evolution and dye degradation

Visible Light-Triggered Catalytic Performance of Reduced Graphene Oxide Decorated With Copper Oxide Nanocomposite for Degradation of Rhodamine B Dye and Kinetics Studies

Herein, novel nanocomposites based on reduced graphene oxide decorated copper oxide nanoparticles (rGO/CuO) were prepared by the in situ co-precipitation method. The structural, morphological, and optical characterization of as-prepared nanocomposites was performed by powdered x-ray diffraction (p-XRD), scanning electron microscopy (SEM), and Fourier-transform infrared (FTIR), Raman, and ultraviolet-visible (UV-Vis) spectroscopy, respectively. The as-prepared nanocomposites exhibited better photocatalytic activity of rhodamine B dye with maximum ~94% degradation in 120 min with a rate constant of 0.2353 min-1 under optimized conditions. Furthermore, the effects of solution pH and catalyst loading are studied on the degradation process. Therefore, this state-of-the-art strategy for the decoration of CuO nanoparticles onto the surface of rGO nanosheets could be an ideal platform for fabricating highly efficient photocatalysts.

Sustainable Natural Deep Eutectic Solvent-Mediated Synthesis of Magnesium Zirconate Nanoparticles: A Photocatalyst for the Degradation of Anti-Viral Drug

The anti-viral drug hydroxychloroquine (HCQ) has captivated significant interest in the pharmaceutical field, as it is a quinolone derivative. Its unrestrained occurrence causes prominent health hazards owing to its persistent, carcinogenic, recalcitrant, and teratogenic nature. Herein, in this work, an experimental investigation was carried out toward the photocatalytic degradation of HCQ drug using magnesium zirconate (MgZrO3) nanoparticles as an effective photocatalyst. A comprehensive characterizations of the as-synthesized material was carried out. The photocatalytic degradation of the HCQ drug was examined with various sources of light energies. The obtained outcomes indicated that ±85% of HCQ was degraded using a MgZrO3 photocatalyst within 30 min of the reaction time under UV-visible (ultraviolet) light irradiation. Further, other significant operational parameters such as various catalyst dosages, HCQ concentrations, pH, scavengers, and salts were examined. The degradation studies revealed that the reaction followed pseudo-first-order kinetics. Hence, this perovskite-type MgZrO3 has grasped profound attention in environmental remediation, significantly in photocatalytic degradation of HCQ drug. This comprehensive research offers green synthesis strategy as a substantial framework for providing effective photocatalyst that addresses contemporary water pollution issues linked to notable results. This aids in targeting era-driven advancements toward a clean and safe future environment.

Development of an antimicrobial inorganic polymer based on fly ash and metakaolin incorporated by nano-TiO2 for reactive dye removal

Advanced and eco-friendly construction materials are being developed to reduce pollution and improve wastewater treatment efficiency. One such material is a photocatalytic nanocomposite that uses industrial wastes and natural substances to eliminate pollution. A recent study explored using an inorganic polymer composite (FM) made from a mixture of 70% fly ash and 30% metakaolin, with sodium hydroxide and sodium silicate as an alkali activator. The study evaluated the mechanical and hydration characteristics of the FM composite after 28 days in 100% humidity at room temperature. The study also examined the effect of adding 2.5 wt.% of Nano-TiO2 to FM composite and how it affects its properties. Results indicate that adding Nano-TiO2 to FM composite enhances its mechanical, antibacterial, and photocatalytic capabilities. Specifically, FM-TiO2 composite showed 90% removal of reactive blue 19 dye effluent in sunlight after 90 min, making it an excellent choice for sustainable wastewater treatment. This study presents a cost-effective, eco-friendly solution to wastewater treatment, with added antimicrobial properties from Nano-TiO2.

Efficient light-driven hydrogen evolution and azo dye degradation over the GdVO4@g-C3N4 heterostructure

A straightforward hydrothermal technique was used for the synthesis of a g-C₃N₄/GdVO₄ (CN/GdV) heterostructure as an alternate material for energy and environmental applications. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) were used to characterize the synthesized g-C₃N₄ (CN), GdVO₄ (GdV), and the CN/GdV heterostructure. The characterization results revealed the distribution of GdV over CN sheets. The as-fabricated materials were tested for their capacity to evolve hydrogen gas and degrade two azo dyes (Amaranth; AMR and Reactive Red2; RR2) in the presence of visible light. When compared to pure CN and GdV, the efficiency of CN/GdV toward hydrogen evolution was high, with H₂ evolution of 8234, 10 838, and 16 234 μmol g^-1 in 4 h, respectively. The CN/GdV heterostructure was able to degrade 96% and 93% of AMR (60 min) and RR2 (80 min), respectively. The enhanced activity with CN/GdV could be attributed to the type-II heterostructure and decreased recombination of charge carriers. The intermediate analysis of AMR and RR2 degradation was conducted using mass spectrometry (MS). The mechanism of photocatalysis was investigated and is discussed based on the optical and electrochemical characterizations. The efficient photocatalytic characteristics of CN/GdV could promote further research on metal vanadate nanocomposite materials.

Decontamination of wastewater containing contaminants of emerging concern by electrooxidation and Fenton-based processes - A review on the relevance of materials and methods

In recent years, there has been an increasingly growing interest regarding the use of electrochemical advanced oxidation processes (EAOPs) which are considered highly promising alternative treatment techniques for addressing environmental issues related to pollutants of emerging concern. In EAOPs, electrogenerated oxidizing agents, such as hydroxyl radical (HO^•), can react non-selectively with a wide range of organic compounds, degrading and mineralizing their structures to unharmful molecules like CO₂, H₂O, and inorganic ions. To this date, a broad spectrum of advanced electrocatalysts have been developed and applied for the treatment of compounds of interest in different matrices, specifically aiming at enhancing the degradation performance. New combined methods have also been employed as alternative treatment techniques targeted at circumventing the major obstacles encountered in Fenton-based processes, such as high costs and energy consumption, which still contribute significantly toward inhibiting the large-scale application of these processes. First, some fundamental aspects of EAOPs will be presented. Further, we will provide an overview of electrode materials which have been recently developed and reported in the literature, highlighting different anode and cathode structures employed in EAOPs, their main advantages and disadvantages, as well as their contribution to the performance of the treatment processes. The influence of operating parameters, such as initial concentrations, pH effect, temperature, supporting electrolyte, and radiation source, on the treatment processes were also studied. Finally, hybrid techniques which have been reported in the literature and critically assess the most recent techniques used for evaluating the degradation efficiency of the treatment processes.

Gadolinium sesquisulfide anchored N-doped reduced graphene oxide for sensitive detection and degradation of carbendazim

Agriculture is having a major role in solving issues associated with food shortages across the globe. Carbendazim (CZM) is one of the fungicides which is commonly used in agriculture to grow crops in large quantities and fast. Monitoring CZM content is in high demand for environmental remediation. The present work deals with the synthesis of gadolinium sesquisulfide anchored Nitrogen-doped reduced graphene oxide (Gd₂S₃/NRGO) through a simple microwave-assisted method. X-ray diffraction and morphological studies confirm the formation of the nanocomposite. Gd₂S₃/NRGO showed enhanced activity both in electrochemical detection and light-driven degradation of CZM compared to Gd₂S₃ and NRGO. Gd₂S₃/NRGO modified glassy carbon electrode (GCE) exhibit a wide linear range of 0.01-450 μM CZM with 0.009 μM LOD using differential pulse voltammetry (DPV). Gd₂S₃/NRGO@GCE showed good selectivity, stability, and recovery (98.13-99.10%) in the river water sample. In addition, Gd₂S₃/NRGO has been explored towards the visible-light-induced degradation of CZM. The reactions conditions were optimized to achieve maximum efficiency. 94% of CZM was degraded within 90 min in presence of Gd₂S₃/NRGO. Mechanism of electrochemical redox reaction and degradation of CZM in presence of Gd₂S₃/NRGO has been explored to the maximum extent possible. Degradation intermediates were identified using LC-MS.

Nitrogen doped carbon spheres from Tamarindus indica shell decorated with vanadium pentoxide; photoelectrochemical water splitting, photochemical hydrogen evolution & degradation of Bisphenol A

At present energy and environmental remediation are of highest priority for the well defined sustainability. Multifunctional materials that solve both the issues are on high demand. In the present work, a simple method has been followed to extract carbon spheres fromTamarindus indica(commonly known astamarind fruit) shelland doped with nitrogen (N-CS). Vanadium pentoxide nanoflakes were decorated aroundN-CS and the resultant is labeled as V₂O₅/N-CS nanocomposite. The spectroscopic, microscopic, elemental mapping and x-ray photoelectron spectroscopic characterization confirm the nitrogen doping and formation of hybrid material. N-CS, V₂O₅, and V₂O₅/N-CS nanocompositehave been evaluated for their efficiency to evolve hydrogen and for degradation of Bisphenol A (BPA) under visible light. In addition, electrocatalytic hydrogen evolution in presence of light has also been evaluated. The DRS spectrum proves the decrease in the bandgap of V₂O₅ upon its decoration around N-CS material. In a photochemical experiment, the V₂O₅/N-CS nanocomposite evolved 18,600 μmolg^-1 of H_2.Electrochemical hydrogen evolution has also been evaluated in presence of light and obtained the onset potential of -60mV with 52 mV dec^-1 Tafel slope value. Scavenger studies indicate superoxide radicals and hydroxyl radicals are the active species responsible for the degradation of BPA. BPA degradation pathway has been predicted with the support of LC-MS results of the intermediates. All these results indicate the synthesized nanocomposite could be an efficient, stable multifunctional material for photocatalytic applications.

Photocatalytic Degradation of Sulfolane Using a LED-Based Photocatalytic Treatment System

Sulfolane is an emerging industrial pollutant detected in the environments near many oil and gas plants in North America. So far, numerous advanced oxidation processes have been investigated to treat sulfolane in aqueous media. However, there is only a few papers that discuss the degradation of sulfolane using photocatalysis. In this study, photocatalytic degradation of sulfolane using titanium dioxide (TiO2) and reduced graphene oxide TiO2 composite (RGO-TiO2) in a light-emitting diode (LED) photoreactor was investigated. The impact of different waters (ultrapure water, tap water, and groundwater) and type of irradiation (UVA-LED and mercury lamp) on photocatalytic degradation of sulfolane were also studied. In addition, a reusability test was conducted for the photocatalyst to examine the degradation of sulfolane in three consecutive cycles with new batches of sulfolane-contaminated water. The results show that LED-based photocatalysis was effective in degrading sulfolane in waters even after three photocatalytic cycles. UVA-LEDs displayed more efficient use of photon energy when compared with the mercury lamps as they have a narrow emission spectrum coinciding with the absorption of TiO2. The combination of UVA-LED and TiO2 yielded better performance than UVA-LED and RGO-TiO2 for the degradation of sulfolane. Much lower sulfolane degradation rates were observed in tap water and groundwater than ultrapure water.

Review of MXene-based nanocomposites for photocatalysis

Since multilayered MXenes (Ti₃C₂T_x, a new family of two-dimensional materials) were initially introduced by researchers at Drexel University in 2011, various MXene-based nanocomposites have received increased attention as photocatalysts owing to their exceptional properties (e.g., rich surface chemistry, adjustable bandgap structures, high electrical conductivity, hydrophilicity, thermal stability, and large specific surface area). Therefore, we present a comprehensive review of recent studies on fabrication methods for MXene-based photocatalysts and photocatalytic performance for contaminant degradation, CO₂ reduction, H₂ evolution, and N₂ fixation with various MXene-based nanocomposites. In addition, this review briefly discusses the stability of MXene-based nanophotocatalysts, current limitations, and future research needs, along with the various corresponding challenges, in an effort to reveal the unique properties of MXene-based nanocomposites.

Recent Developments of TiO2-Based Photocatalysis in the Hydrogen Evolution and Photodegradation: A Review

The growth of industrialization, which is forced to use non-renewable energy sources, leads to an increase in environmental pollution. Therefore, it is necessary not only to reduce the use of fossil fuels to meet energy needs but also to replace it with cleaner fuels. Production of hydrogen by splitting water is considered one of the most promising ways to use solar energy. TiO₂ is an amphoteric oxide that occurs naturally in several modifications. This review summarizes recent advances of doped TiO₂-based photocatalysts used in hydrogen production and the degradation of organic pollutants in water. An intense scientific and practical interest in these processes is aroused by the fact that they aim to solve global problems of energy conservation and ecology.

Localized Building Titania-Graphene Charge Transfer Interfaces for Enhanced Photocatalytic Performance

Achieving high photocatalytic activity of titania-graphene composites calls for well-controlled titania size and efficient charge transfer interfaces. However, it is rather difficult because of easy restacking of graphene sheets and random nucleation and growth of titania nanoparticles in solution. Here, we reported a facile way to control the TiO₂ sizes and interfaces by localizing the nucleation and growth of titania on graphene sheets, which prohibits both restacking of graphene and random growth of TiO₂. As a result, a composite with controllably less than 10-nm-sized TiO₂ nanoparticles evenly distributed on thin graphene sheets was achieved. Thanks to the small size of titania and efficient charge transfer interfaces, the TiO₂/graphene composite exhibits a significant enhancement of photocatalytic H₂ evolution activity, reaching 1.35 mmol g^-1 h^-1. Furthermore, the composite also shows high photocatalytic activity on dye degradation under visible light illumination.