Inorganic–organic nanohybrid of MoS2-PANI for advanced photocatalytic application

Tailoring functional two-dimensional nanohybrids: A comprehensive approach for enhancing photocatalytic remediation

Photocatalysis is gaining prominence as a viable alternative to conventional biohazard treatment technologies. Two-dimensional (2D) nanomaterials have become crucial for fabricating novel photocatalysts due to their nanosheet architectures, large surface areas, and remarkable physicochemical properties. Furthermore, a variety of applications are possible with 2D nanomaterials, either in combination with other functional nanoparticles or by utilizing their inherent properties. Henceforth, the review commences its exploration into the synthesis of these materials, delving into their inherent properties and assessing their biocompatibility. Subsequently, an overview of mechanisms involved in the photocatalytic degradation of pollutants and the processes related to antimicrobial action is presented. As an integral part of our review, we conduct a systematic analysis of existing challenges and various types of 2D nanohybrid materials tailored for applications in the photocatalytic degradation of contaminants and the inactivation of pathogens through photocatalysis. This investigation will aid to contribute to the formulation of decision-making criteria and design principles for the next generation of 2D nanohybrid materials. Additionally, it is crucial to emphasize that further research is imperative for advancing our understanding of 2D nanohybrid materials.

Mechanistic view of MoS2 confined chitosan-polyaniline hybrid composite for the photo-oxidation of cationic dyes

In this article, we describe the formulation of polyaniline-chitosan/MoS2 (PANI-CS @MoS2) blended composite and evaluated its efficiency to degrade the dye molecules Rhodamine B (RhB) and Malachite Green (MG) under visible light. In the photocatalytic mechanism, the CS acts as an electron carrier and binding agent during the oxidation reaction to decrease the recombination of electrons and holes generated by the irradiation of light. FTIR, XPS, XRD, TG, Zeta Potential, UV, SEM, AFM and TEM were used to characterize the PANI-CS@MoS2 composite after it had been synthesized. For the degradation analysis, 30 mg/L concentrations of 50 mL MG and RhB dye solutions were used. The recommended dosage of the composite was 100 mg. For MG and RhB dyes, the colour removal rates were 96.2 % and 91.5 %, respectively, under exposure to visible light and at the pH ranges of 8-11. After being exposed to visible light for 60 min, the whole decay process was accomplished. The photocatalyst offers great extensibility up to five iterations. The Langmuir-Hinshelwood kinetic model governs the rate of dye molecules degradation. The result of the study revealed that the PANI-CS@MoS2 composite matrix perhaps be a trustworthy and practical substrate for the efficient refinement of dye-deteriorated water⁠⁠⁠⁠⁠⁠⁠.

Fabrication of an S-Scheme Heterojunction Photocatalyst MoS2/PANI with Greatly Enhanced Photocatalytic Performance

As a promising catalyst, MoS2 has been widely studied owing to its high chemical reactivity, excellent electrical carrier mobility, good optical properties, and narrow band gap. However, the high recombination rate of photoinduced charge carriers limits its practical application in photocatalysis. In this study, MoS2 was coupled with PANI to fabricate an S-scheme heterojunction MoS2/PANI. The synthesized products were characterized systematically, and their photocatalytic properties were evaluated by photocatalytic degradation of norfloxacin (NOR) and rhodamine B (RhB). The obtained results indicated that the fabricated MoS2/PANI inorganic-organic heterojunction displayed tremendously enhanced photocatalytic activity. The degradation efficiencies for 60 mg L-1 of NOR and RhB are 86 and 100% under the simulated sunlight irradiation for 1 h with 10 mg of catalyst, which are 13 and 47 times higher than those of pure MoS2, respectively. Interestingly, it is superior to the previously reported related materials. The remarkably enhanced photocatalytic activity of MoS2 is assigned to the high charge conductivity feature of PANI and the formed S-scheme heterojunction that result in a steric separation of holes and electrons and conserve the initial powerful redox ability of the parent catalysts. This study provides a facile method to greatly improve the photocatalytic activity of MoS2 and facilitates its application for highly efficient removal of organic pollutants, such as antibiotic drugs and organic dyes, utilizing solar energy.

A polyaniline functionalized NiFeP nanosheet array-based electrochemical immunosensor using Au/Cu2O nanocubes as a signal amplifier for the detection of SARS-CoV-2 nucleocapsid protein

Coronavirus disease 2019 (COVID-19) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which emerged as a novel pathogen in 2019. The virus is responsible for a severe acute respiratory syndrome outbreak, affecting the respiratory system of infected individuals. COVID-19 is a super amplifier of basic diseases, and the disease with basic diseases is often more serious. Controlling the spread of the COVID-19 pandemic relies heavily on the timely and accurate detection of the virus. To resolve the problem, a polyaniline functionalized NiFeP nanosheet array-based electrochemical immunosensor using Au/Cu₂O nanocubes as a signal amplifier is fabricated for the detection of SARS-CoV-2 nucleocapsid protein (SARS-CoV-2 NP). Polyaniline (PANI) functionalized NiFeP nanosheet arrays are synthesized as an ideal sensing platform for the first time. PANI is coated on the surface of NiFeP by electropolymerization to enhance biocompatibility, beneficial for the efficient loading of the capture antibody (Ab₁). Significantly, Au/Cu₂O nanocubes possess excellent peroxidase-like activity and exhibit outstanding catalytic activity for the reduction of H₂O₂. Therefore, Au/Cu₂O nanocubes combine with a labeled antibody (Ab₂) through the Au-N bond to form labeled probes, which can effectively amplify current signals. Under optimal conditions, the immunosensor for the detection of SARS-CoV-2 NP shows a wide linear range of 10 fg mL^-1-20 ng mL^-1 and a low detection limit of 1.12 fg mL^-1 (S/N = 3). It also exhibits desirable selectivity, repeatability, and stability. Meanwhile, the excellent analytical performance in human serum samples confirms the practicality of the PANI functionalized NiFeP nanosheet array-based immunosensor. The electrochemical immunosensor based on the Au/Cu₂O nanocubes as a signal amplifier demonstrates great potential for application in the personalized point-of-care (POC) clinical diagnosis.

Synthesis of zeolite-doped polyaniline composite for photocatalytic degradation of methylene blue from aqueous solution

The generation of wastewater has increased rapidly with the expansion of industries, hence, posing a risk to human health and the environment. The development of novel materials and technologies for textile wastewater treatment is constantly evolving. In this work, the photocatalytic degradation of methylene blue employing ZSM-5 zeolite-doped polyaniline composites is presented. To fabricate ZSM-5-based polyaniline (PANI) composites, the simple approach of in situ oxidative polymerization has been adopted. Different weight ratios of ZSM-5 have been used for the synthesis, and samples have been labelled as PAZe-1, PAZe-5, and PAZe-10. Different characterization techniques were used to characterize the prepared composites, including field-emission scanning electron microscope (FESEM), transmission electron microscope (TEM), Fourier transform infrared (FT-IR), X-ray diffraction (XRD), and thermo-gravimetry analysis (TGA). The photocatalytic performance of polyaniline, ZSM-5, and their composites was assessed by monitoring the degradation of methylene blue in the presence of visible light. Degradation results of the polyaniline-doped composites were found to be better than that of the polyaniline alone. When the photocatalytic efficiencies of different composites were compared, the PAZe-1 showed the best performance, with 99.9% degradation efficiency after 210 min of irradiation, while PANI, PAZe-5, PAZe-10, and ZSM-5 show 38%, 82%, 71%, and 99% removal efficiency. Apart from methylene blue, the composite PAZe-1 was further explored for the degradation of other organic pollutants such as methyl orange, chlorpyrifos, 2,4-dichlorophenoxy acetic acid, and p-nitroaniline. To determine the reactive species involved in the photocatalysis mechanism, scavenger studies were performed.

Role of polyaniline in accomplishing a sustainable environment: recent trends in polyaniline for eradicating hazardous pollutants

Attaining a sustainable environment has become a prime area of research interest, as it is an utmost necessity for a healthy life. Hence, ample studies have been carried out in adopting different processes and utilizing various materials to attain the goal. Herein, we present an exclusive discussion on one such material, i.e., polyaniline (PANI) and its derivatives. Being an intrinsic conducting type, it has grabbed more attention due to its durability in different doped/un-doped states, promptness in structural alteration, and solution processability. This review presents an exhaustive discussion on published reports showing utilization of PANI and its derivative in various forms like pure and composites, for cleaning the environment through adsorption, photodegradation, etc., and the various methods adopted in order to achieve an optimum operating condition to obtain the maximum outcome. In addition to these merits and demerits, various technical challenges faced with materials have been also presented. Therefore, it is expected that this piece of work, presenting the exhaustive discussion on PANI and; its derivatives would help to develop a better understanding of this excellent conducting polymer PANI and provide a state of art on the role of this material for attaining sustainable surroundings for the living beings.

Nanosheets- and nanourchins-like nanostructures of MoSe2 for photocatalytic water purification: kinetics and reusability study

In this paper, we are reporting a simple hydrothermal technique for preparation of MoSe₂ nanostructures (nanourchins and nanosheets) using selenium and sodium molybdate as precursors. Samples are characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Raman spectroscopy, UV-Vis spectroscopy, Brunauer-Emmett-Teller (BET), and X-ray photoelectron spectroscopy (XPS). The FESEM revealed that the morphology of materials was varying significantly by changing pH value during synthesis. Photocatalytic degradation of anionic dye (MO), cationic dye (MB), and reduction of Cr(VI) into Cr(III) were performed. Nanosheets and nanourchins showed higher photocatalytic activity, enhanced photocatalytic degradation efficiency is correlated with the higher ^•OH radical concentration, crystallinity of material, and large surface area as evident through XPS, XRD, and BET, respectively. Photocatalysis mechanism along with role of reactive species (^•OH and holes) were explained using trapping experiments. Identification of degraded products was carried out using high-performance liquid chromatography (HPLC). Reaction kinetics and reusability of materials were also studied; wherein, it was observed that the materials have reusable properties.

BiOCl/WS2 hybrid nanosheet (2D/2D) heterojunctions for visible-light-driven photocatalytic degradation of organic/inorganic water pollutants

This report presents the superior visible-light-driven photocatalytic response of novel 2D/2D BiOCl/WS₂ (BW _X ) hybrid nanosheet heterojunctions prepared by a simple solution based sonochemical technique. These BW _X hybrid nanosheets are composed of 2D transition metal dichalcogenide material WS₂ and BiOCl nanosheets. The comparative study of photocatalytic activity of BiOCl and BiOCl/WS₂ hybrid nanosheets is carried out via photodegradation of Malachite Green (MG) and photoreduction of heavy metal ion Cr(vi) under visible light irradiation. The quantum efficiency of the samples is estimated in terms of the incident photon to electron conversion efficiency (IPCE) measurements. Nearly 98.4% of the MG degradation was achieved over BiOCl/WS₂ (2%) photocatalyst in 45 min of irradiation. BiOCl/WS₂ (2%) hybrid nanosheet catalyst showed the highest external quantum efficiency (EQE) in both the UV and visible regimes. This accomplishment demonstrated the promise of commercial application of the 2D/2D BiOCl/WS₂ (2%) hybrid nanosheet photocatalyst.

Improved Surface Functional and Photocatalytic Properties of Hybrid ZnO-MoS2-Deposited Membrane for Photocatalysis-Assisted Dye Filtration

The synergistic mechanism of photocatalytic-assisted dye degradation has been demonstrated using a hybrid ZnO-MoS₂-deposited photocatalytic membrane (PCM). Few layers of MoS₂ sheets were produced using the facile and efficient surfactant-assisted liquid-phase exfoliation method. In this process, hydrophilic moieties of an anionic surfactant were adsorbed on the surface of MoS₂, which aided exfoliation and promoted a stable dispersion due to the higher negative zeta potential of the exfoliated MoS₂ sheets. Further, the decoration of ZnO on the exfoliated MoS₂ sheets offered a bandgap energy reduction to about 2.77 eV, thus achieving an 87.12% degradation of methylene blue (MB) dye within 15 min of near UV-A irradiation (365 nm), as compared with pristine ZnO achieving only 56.89%. The photocatalysis-enhanced membrane filtration studies on the ZnO-MoS₂ PCM showed a complete removal of MB dye (~99.95%). The UV-assisted dye degradation on the ZnO-MoS₂ PCM offered a reduced membrane resistance, with the permeate flux gradually improving with the increase in the UV-irradiation time. The regeneration of the active ZnO-MoS₂ layer also proved to be quite efficient with no compromise in the dye removal efficiency.

Hybridized 2D Nanomaterials Toward Highly Efficient Photocatalysis for Degrading Pollutants: Current Status and Future Perspectives

Organic pollutants including industrial dyes and chemicals and agricultural waste have become a major environmental issue in recent years. As an alternative to simple adsorption, photocatalytic decontamination is an efficient and energy-saving technology to eliminate these pollutants from water environment, utilizing the energy of external light, and unique function of photocatalysts. Having a large specific surface area, numerous active sites, and varied band structures, 2D nanosheets have exhibited promising applications as an efficient photocatalyst for degrading organic pollutants, particularly hybridization with other functional components. The novel hybridization of 2D nanomaterials with various functional species is summarized systematically with emphasis on their enhanced photocatalytic activities and outstanding performances in environmental remediation. First, the mechanism of photocatalytic degradation is given for discussing the advantages/shortcomings of regular 2D materials and identifying the importance of constructing hybrid 2D photocatalysts. An overview of several types of intensively investigated 2D nanomaterials (i.e., graphene, g-C₃ N₄ , MoS₂ , WO₃ , Bi₂ O₃ , and BiOX) is then given to indicate their hybridized methodologies, synergistic effect, and improved applications in decontamination of organic dyes and other pollutants. Finally, future research directions are rationally suggested based on the current challenges.

Self-Assembled Two-Dimensional Molybdenum Disulfide Nanosheet Geno-Interface for the Detection of Salmonella

This report presents a novel lab-on-a-paper (LoP)-based device coupled with a molybdenum disulfide nanosheet (MoS2NS)-modified electrochemical genosensor for detecting Salmonella-specific DNA. Conductive electrodes were grafted on a paper-based substrate employing a stencil printing technique, and MoS2NS was decorated on the working electrode. MoS2NS has strong affinity toward nucleo bases, which made it a best sensing interface for the immobilization of DNA. Morphological, optical, and structural characterizations were accomplished using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), UV-vis spectroscopy (UV-vis), and Raman spectroscopy, repectively. The current studies of an electrochemical genosensor demonstrated a good linear detection range from 100-20 nM and a low limit of detection of 20 nM toward Salmonella DNA with R 2 = 0.991. The proposed LoP-based genosensor confirmed as a better sensing podium and an effectual immobilization matrix for DNA.