Enhanced photocatalytic degradation of rhodamine B and malachite green employing BiFeO3/g-C3N4 nanocomposites: An efficient visible-light photocatalyst

Controlled solvothermal synthesis of self-assembled SrTiO3 microstructures for expeditious solar-driven photocatalysis dye effluents degradation

In this work, the self-assembled SrTiO3 (STO) microstructures were synthesized via a facile one-step solvothermal method. As the solvothermal temperature increased from 140 °C to 200 °C, the STO changed from a flower-like architecture to finally an irregularly aggregated flake-like morphology. The photocatalytic performance of as-synthesized samples was assessed through the degradation of rhodamine B (RhB) and malachite green (MG) under simulated solar irradiation. The results indicated that the photocatalytic performance of STO samples depended on their morphology, in which the hierarchical flower-like STO synthesized at 160 °C demonstrated the highest photoactivities. The photocatalytic enhancement of STO-160 was benefited from its large surface area and mesoporous configuration, hence facilitating the presence of more reactive species and accelerating the charge separation. Moreover, the real-world practicality of STO-160 photocatalysis was examined via the real printed ink wastewater-containing RhB and MG treatment. The phytotoxicity analyses demonstrated that the photocatalytically treated wastewater increased the germination of mung bean seeds, and the good reusability of synthesized STO-160 in photodegradation reaction also promoted its application in practical scenarios. This work highlights the promising potential of tailored STO microstructures for effective environmental remediation applications.

Effect of Morphology Modification of BiFeO3 on Photocatalytic Efficacy of P-g-C3N4/BiFeO3 Composites

This current study assessed the impacts of morphology adjustment of perovskite BiFeO3 (BFO) on the construction and photocatalytic activity of P-infused g-C3N4/U-BiFeO3 (U-BFO/PCN) heterostructured composite photocatalysts. Favorable formation of U-BFO/PCN composites was attained via urea-aided morphology-controlled hydrothermal synthesis of BFO followed by solvosonication-mediated fusion with already synthesized P-g-C3N4 to form U-BFO/PCN composites. The prepared bare and composite photocatalysts' morphological, textural, structural, optical, and photocatalytic performance were meticulously examined through various analytical characterization techniques and photodegradation of aqueous rhodamine B (RhB). Ellipsoids and flakes morphological structures were obtained for U-BFO and BFO, and their effects on the successful fabrication of the heterojunctions were also established. The U-BFO/PCN composite exhibits 99.2% efficiency within 20 min of visible-light irradiation, surpassing BFO/PCN (88.5%), PCN (66.8%), and U-BFO (26.1%). The pseudo-first-order kinetics of U-BFO/PCN composites is 2.41 × 10-1 min-1, equivalent to 2.2 times, 57 times, and 4.3 times of BFO/PCN (1.08 × 10-1 min-1), U-BFO, (4.20 × 10-3 min-1), and PCN, (5.60 × 10-2 min-1), respectively. The recyclability test demonstrates an outstanding photostability for U-BFO/PCN after four cyclic runs. This improved photocatalytic activity exhibited by the composites can be attributed to enhanced visible-light utilization and additional accessible active sites due to surface and electronic band modification of CN via P-doping and effective charge separation achieved via successful composites formation.

An insight decipher on photocatalytic degradation of microplastics: Mechanism, limitations, and future outlook

Plastic material manufacturing and buildup over the past 50 years has significantly increased pollution levels. Microplastics (MPs) and non-biodegradable residual plastic films have become the two most pressing environmental issues among the numerous types of plastic pollution. These tiny plastic flakes enter water systems from a variety of sources, contaminating the water. Since MPs can be consumed by people and aquatic species and eventually make their way into the food chain, their presence in the environment poses a serious concern. Traditional technologies can remove MPs to some extent, but their functional groups, stable covalent bonds, and hydrophobic nature make them difficult to eliminate completely. The urgent need to develop a sustainable solution to the worldwide contamination caused by MPs has led to the exploration of various techniques. Advanced oxidation processes (AOPs) such as photo-catalytic oxidation, photo-degradation, and electrochemical oxidation have been investigated. Among these, photocatalysis stands out as the most promising method for degrading MPs. Photocatalysis is an environmentally friendly process that utilizes light energy to facilitate a chemical reaction, breaking down MPs into carbon dioxide and water-soluble hydrocarbons under aqueous conditions. In photocatalysis, semiconductors act as photocatalysts by absorbing energy from a light source, becoming excited, and generating reactive oxygen species (ROS). These ROS, including hydroxyl radicals (•OH) and superoxide ions ( [Formula: see text] ), play a crucial role in the degradation of MPs. This extensive review provides a detailed exploration of the mechanisms and processes underlying the photocatalytic removal of MPs, emphasizing its potential as an efficient and environmentally friendly approach to address the issue of plastic pollution.

Photodegradation of rhodamine-B in aqueous environment using visible-active gC3N4@CS-MoS2 nanocomposite

Rapid industrial expansion leads to environmental pollution especially in an aqueous environment. Photocatalytic degradation is one of the most efficient and environmentally friendly techniques used to treat industrial pollution due to its complete degradation capability of a variety of water contaminants to their non-toxic state. Graphitic carbon nitride (gC3N4) and molybdenum disulfide (MoS2) provide efficient dye degradation, but MoS2 has few disadvantages. Hence, chitosan (CS) supported gC3N4-MoS2 hybrid nanocomposite was developed in this study to reduce these issues by accelerating the degradation of dye molecules such as rhodamine-B under visible light. The prepared gC3N4@CS-MoS2 hybrid nanocomposite was thoroughly characterized using various analytical tools including FTIR, XRD, SEM, EDX, XPS, UV-Visible, and PL spectra. Several influencing parameters such as irradiation time, initial pH, dosage, and initial dye concentration were optimized by batch mode. The photodegradation of rhodamine-B could be induced by the heterogeneous gC3N4@CS-MoS2-water hybrid nanocomposite. The narrow band gap of gC3N4@CS-MoS2 (1.80 eV) makes it suitable for effective degradation of rhodamine-B due to more active in the visible region and attained its highest degradation efficiency of 99% after 40 min at pH 8 with minimum dosage of 60 mg. The possible degradation mechanism was tentatively proposed for rhodamine-B dye molecules from aqueous environment. The present work shows a novel photocatalyst for the purification and detoxification of dye molecules as well as other water contaminants found in polluted wastewater.

An S-scheme heterojunction between Mn/Mg co-doped BiFeO3 and g-C3N4 nanosheets for photodegradation of organic pollutants

BiFe1-2xMnxMgxO3 (BFMM, x = 0-8%) was mixed with exfoliated g-C3N4 (GCN) to form a composite for establishing an S-scheme heterojunction for photodegradation. BFMM was synthesized by sol-gel method, and showed a decreased band gap from 2.24 eV to 1.75 eV as x increased from 0% to 7%, allowing a more efficient absorption of sunlight. GCN was prepared by thermal polymerization of melamine and then exfoliated to form nanosheets by sulfur acid in order to increase the specific surface area and thus increase reaction sites. A composite with a weight ratio of BFMM/GCN equal to 1 : 3 was prepared by sintering the powder mixture at 300 °C. Such a composite showed a greatly improved efficiency in photodegradation of methylene blue, which was over 6 times faster than pristine BiFeO3, and the Mn/Mg co-doping improved the efficiency by 48%. The Mott-Schottky plots showed that both GCN and BFMM are n-type semiconductors with flat-band potentials of -0.79 and +0.11 V (vs. NHE), respectively. So, the band alignment allowed the S-scheme to work, leading to an efficient separation of photogenerated electrons and holes, which was confirmed by the greatly increased photocurrents measured with the composites.

Doped graphitic carbon nitride (g-C3N4) catalysts for efficient photodegradation of tetracycline antibiotics in aquatic environments

Tetracyclines (TCs) antibiotics are very common and often used in both human and veterinary medicines. More than 75% of TCs are excreted in an active condition and released into the environment, posing a risk to the ecosystem and human health. Residual antibiotics are in global water bodies, causing antibiotic resistance and genotoxicity in humans and aquatic organisms. The ever-increasing number of multi-resistant bacteria caused by the widespread use of antibiotics in the environment has sparked a renewed interest in developing more sustainable antibiotic degradation processes. In this regard, photodegradation technique provides a promising solution to resolve this growing issue, paving the way for complete antibiotic degradation with the generation of non-toxic by-products. As a fascinating activity towards visible light range shown by semiconductor, graphitic carbon nitride (g-C₃N₄) has a medium bandgap, non-toxicity, chemically stable complex, and thermally great strength. Recent studies have concentrated on the performance of g-C₃N₄ as a photocatalyst for treating wastewater. Pure g-C₃N₄ exhibits limited photocatalytic activity due to insufficient sunlight usage, small surface area, and a high rate of recombination of electron and hole ([Formula: see text] & [Formula: see text]) pairs created in photocatalytic activity. Doping of g-C₃N₄ is a very effective method for improving the activity as element doped g-C₃N₄ shows excellent bandgap and electronic structure. Doping significantly broadens the light-responsive range and reduces recombination of e^- & h⁺ pairs. Under above context, this review provides a systematic and comprehensive outlook of designing doped g-C₃N₄ as well as efficiency for TCs degradation in aquatic environment.

Visible-light driven excellent photocatalytic degradation of ofloxacin antibiotic using BiFeO3 nanoparticles

The extensive exploration of multiferroic materials for degradation of contaminants and environmental remediation is promptly strengthened because of their distinct applications. BiFeO₃, a prominent class of multiferroics, have received immense attention in recent times. Present study reports the synthesis of a highly crystalline BiFeO₃ via facile combustion method. The prepared catalyst was characterized using different techniques like XRD, FTIR, FESEM, EDS, XPS, DRS and PL. From DRS results, the energy band gap of BiFeO₃ was computed as 2.1 eV which was suitable enough for its exploration as a visible light photocatalyst. Therefore, BiFeO₃ was efficiently utilized for the degradation of ofloxacin drug under the exposure of visible light. The obtained results depicted 80% ofloxacin degradation under optimized conditions (pH 8, 0.5 g/L catalyst dose and 10 mg/L drug concentration) in 180 min. Pseudo first order kinetics was followed with rate constant 0.0097 min^-1, as inferred from the kinetic studies. Furthermore, 64% TOC reduction was attained by utilizing the prepared catalyst under optimum conditions. Additionally, the photocatalytic experiments showed excellent degradation efficiency even after five cycles which demonstrated good stability of the fabricated catalyst.

Noble metal-free doped graphitic carbon nitride (g-C3N4) for efficient photodegradation of antibiotics: progress, limitations, and future directions

Graphitic carbon nitride (g-C₃N₄) is well recognised as one of the most promising materials for photocatalytic activities such as environmental remediation via organic pollution elimination. New methods of nanoscale structure design introduce tunable electrical characteristics and broaden their use as visible light-induced photocatalysts. This paper summarises the most recent developments in the design of g-C₃N₄ with element doping. Various methods of introducing metal and nonmetal elements into g-C₃N₄ have been investigated in order to simultaneously tune the material's textural and electronic properties to improve its response to the entire visible light range, facilitate charge separation, and extend charge carrier lifetime. The degradation of antibiotics is one of the application domains of such doped g-C₃N₄. We expect that this research will provide fresh insights into clear design methods for efficient photocatalysts that will solve environmental challenges in a sustainable manner. Finally, the problems and potential associated with g-C₃N₄-based nanomaterials are discussed. This review is expected to encourage the ongoing development of g-C₃N₄-based materials for greater efficiency in photocatalytic antibiotic degradation.