Electrocatalysis utilizing 2D materials is an encouraging approach for advancing sustainable energy conversion technologies. This review explores the strategies employed to achieve robust electrocatalytic activity of 2D materials in key reactions, namely, the OER, HER, and CO2RR. The distinct structural and electrical characteristics of 2D materials offer opportunities for rapid catalytic performance, indicating significant energy efficiency and selectivity. We systematically discuss the factors governing the electrocatalytic efficiency of two-dimensional materials, including their intrinsic properties, surface modification techniques, heterostructure engineering, and the role of defects. Furthermore, we summarize the recent advances in experimental and theoretical studies to understand the fundamental mechanisms of 2D materials with respect to their catalytic behavior. For the HER, OER, and ORR, defect engineering, phase engineering, interface engineering, and heteroatom doping techniques have been explored. In addition, in the case of the CO2RR, surface modification, surface-structure tuning, and electrolyte and electrolyzer optimization strategies were examined. This review emphasizes prospective two-dimensional materials as efficient and sustainable electrocatalysts for energy conversion processes. Moreover, it provides future insights into this rapidly evolving field and highlights the possible challenges. In conclusion, it aims to serve as a remarkable resource for researchers seeking to harness the potential response of two-dimensional materials for sustainable energy conversion applications.

Because of their uncontrolled proliferation, biofilm-based diseases pose severe hazards to human life. Biofilm production makes the immune system resistant to antibiotics, emphasizing the need of prevention in human health. When pathogenic bacteria and fungi are injected into people, they develop biofilms and cause waterborne illnesses. Understanding the methods by which these biofilms arise is thus critical for creating techniques for removing them from water systems. This overview introduces biofilms, highlighting adhesion and detachment phenomena and growth basics. Following that, their production and stability in drinking water distribution systems (DWDS) and their influence on living organisms are explored. This review focuses on biofilm treatment techniques such as ultrasound, photothermal and photodynamic methods, microbubbles, and chemical approaches (via nanomaterials). This review explores the latest physical and chemical techniques aimed at preventing biofilm development. It highlights chloramine, a stable chemical used in DWDS to suppress microbial growth, along with its decay kinetics. Additionally, it presents future study goals and recommendations regarding chloramine as a viable chemical for limiting microbial development..

2D structures have numerous attributes that make them effective for the fabrication of sensing devices. The aim of this review is to provide an update on the recent developments in the field of sensor devices made from atomically thin 2D materials.

Metal oxide nanoparticles (NPs) and their nanocomposites (NCs) are reviewed comprehensively for wastewater treatment. The controlled textural and morphological properties, variable surface chemistry, broad specific areas of the surface, crystalline nature, and excess availability of nanomaterials are the main factors responsible for adsorption and photocatalysis degradation behavior of nanostructured metal oxides (MOs) and their NCs. Oxides of iron, titanium, copper, zinc, tungsten, metal oxides, and graphene-based MO NCs with variable crystalline, morphological, and structural properties are studied, with an emphasis on recent challenges, improvements, and opportunities for adsorptive removal and photodegradation of organic contaminants such as dyes. This study also helps us to understand photocatalytic metal oxides and their NCs with photocatalytic action-related properties. Remarkable photocatalytic abilities, low-cost feasible approaches to processing and controlled band gap products render the use of metal oxides an extremely important photocatalytic approach for the degradation of organic pollutants. The thesis presents an excellent platform for researchers working on water treatment composites containing metal oxides and those working on MOs and NCs with adsorption photo-degrade, etc.

Developing innovative technologies for the effective treatment of organic contaminants comprising agricultural wastes, industrial dyes, and chemicals is gaining extraordinary importance across the globe. In the last few years, photocatalytic degradation has become an effective and established route to eliminate these pollutants from aqueous solution relative to simple adsorption. 2D nanomaterials exhibit great potential as an effectual photocatalyst in degradation of contaminants, especially hybridization with other functional components due to wide-ranging band structures, sufficient active sites, and significant specific surface area. Herein, the unique hybridization of 2D nanomaterials with numerous functional species is reviewed comprehensively by highlighting their improved photocatalytic performances and remarkable environmentally friendly activity. The chapter outlines the mechanism of photocatalytic degradation to explore the advantages/disadvantages of regular 2D materials and discover the significance of developing hybrid 2D photocatalysts.

In recent years, the process of photocatalytic degradation is considered as one of the outstanding strategies for removing pollutants from aqueous solutions than traditional adsorption. The wide-ranging band structures, sufficient active sites, and significant specific surface area of 2D materials offer them a significant amount of potential as an effective photocatalyst in the degradation of contaminants. This potential is especially evident in hybridization with other functional components such as metal oxides, sulfides, carbon nitrides, and graphene, amongst others. In this article, among the many available strategies, the one-of-a-kind hybridization of 2D materials with a large number of functional species is examined in great detail, with a focus on the enhanced photocatalytic performances and remarkable activity that is friendly to the environment that it enables for water desalination. Current developments in 2D hybrid photocatalysts for environmental remediation are discussed in this feature review article. The current review will inspire the reader to have a better understanding of the feasible optimization of 2D hybrid photocatalysts for solar energy harvesting, and at the end, the authors' recommendations aligned with future challenges and opportunities will set the path for readers. In addition, several different hybridization approaches are investigated.

A bismuth-based material serves as an interesting and innovative class of visible-light-driven photocatalysts that have paid a lot of attraction towards exceptional photo-oxidation capacity. The great progress for the decomposition of water oxidation and organic contaminants have been documented with the aid of photocatalytic strategies. At present, the classification of Bi-based photocatalysts can be given as bismuth metal, binary sulfides, multicomponent oxides, bismuth oxyhalides, binary oxides, and so forth. Although Bi provides advanced outcomes for photocatalysts towards energy development and environmental remediation, their productivity still is not at supreme level. Prompting recombination of e - -h + pairs (photogenerated) along with characteristic structural instability has restricted its applied usage. To resolve these issues, some strategies have been tendency to bismuth-rich strategy, elemental doping, facet control, defect engineering, and heterojunction. In this article, we represent a complete outline of their electronic structures, fundamental compositions, and synthesis schemes for numerous bismuth-based photocatalysts. Moreover, a number of environmental applications also have been conferred in detail, for instance degradation of water pollutants, H 2 -evolution, and CO 2 photoreduction, N 2 -fixation, as well as treatment of atmospheric pollutants. Utilizing the structural-property-activity associations, comprehensive methodologies for improvement of their photocatalytic progress have been discussed, including introduction of oxygen vacancies (Ov), heterojunction construction, bismuth-rich strategy, and morphology/facet control. Finally, a superior understanding for development of Bi-based photocatalysts and realistic design headed for environmental remediation via solar energy harvesting are outlined.

Background: Metal oxide (MO) nanomaterials and related nanocomposites have been extensively studied for their potential use in water treatment. Because of their controlled morphologies, texture qualities, variable surface chemistry, distinct crystalline nature, high stability, and tunable band edges, MO nanostructured materials are highly selective towards deleting organic contaminants and heavy metal ions via adsorption and semiconductor photocatalysis. Metal-enhanced photocatalysis has recently received increasing interest, mainly due to the ability of the metal to directly or indirectly degrade pollutants. A diverse selection of MOs, with titanium dioxide (TiO2), zinc oxide (ZnO), iron oxides (IO), and tungsten (W), as well as graphene-MOs nanocomposites with variable structure, crystalline, and morphological properties, offers a powerful platform for the growth of effective catalysts. Methods: The current work discusses novel advancements and potential for the removal of adsorptive and photocatalytic degradation of organic compounds (phenolic, pesticide molecules, dyes, and so on) as well as heavy metal ions using semiconductor materials. A photocatalyst based on a MO-scheme heterostructure can manage the appropriate conduction band (CB) and valence band (VB) locations, securing considerable redox aptitude. This review should be of interest to the broad readership dealing with applied and fundamental aspects of water treatments and material sciences. Various strategies including surface modification, plasmonic enhancement, and metal cocatalysts have been introduced to enhance photocatalytic performance. Significant findings: The current article discussed the significantly utilized synthesis strategies and mechanism of heterojunction photocatalysts using a Z-scheme. Furthermore, adsorption sections guarantee that mercury, chromium, cadmium, arsenic, and lead-based ions are successfully removed from polluted water via the adsorption route. Numerous characteristics, such as concentration, coexisting ions, pH, and kind of chemical have converged to comprehend the adsorption procedure. The technological challenges and future approaches are discussed to maximize the photocatalytic and adsorption efficacy and the reusability of MO-based nanomaterials for water security. (C) 2022 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Two-dimensional (2D) MXenes are a hotspot for environmental photocatalysis attributable to their extreme conductivity and tunable hydrophilicity. MXenes, as a prospective photocatalytic contender, provide quick photogenerated charge carrier isolation, resulting in abundant availability for surface functional groups in light-harvesting promising materials, as well as laying the groundwork for better photoconversion competency. This review presents a detailed discussion of recent research on MXene photocatalyst production methods and photocatalytic performance for pollutant degradation and water splitting with the addition of CO2 reduction. More importantly, when mixed with other traditional photocatalysts such as metal oxide, metal sulfide, g-C3N4, and so on shows tremendous performance, MXenes are widely used as co-catalysts to increase the efficacy of photocatalytic activities. Furthermore, the stability of MXene-based nanocomposite photocatalysts is briefly explored to expose the distinctive belongings of MXene-based nanocomposites; in the last section, future recommendations are also presented with conclusive results remarks.

In this work, synthesis of graphene oxide (GO) and reduced graphene oxide (rGO) was realized through a modified Hummers route. Different concentrations (5 and 10 wt%) of Ag were doped in MoS2and rGO using a hydrothermal technique. Synthesized Ag-MoS2and Ag-rGO were evaluated through XRD that confirmed the hexagonal structure of MoS2along with the transformation of GO to Ag-rGO as indicated by a shift in XRD peaks while Mo-O bonding and S=O functional groups were confirmed with FTIR. Morphological information of GO and formation of MoS2nanopetals as well as interlayer spacing were verified through FESEM and HRTEM respectively. Raman analysis was employed to probe any evidence regarding defect densities of GO. Optical properties of GO, MoS2, Ag-rGO, and Ag-MoS2were visualized through UV-vis and PL spectroscopy. Prepared products were employed as nanocatalysts to purify industrial wastewater. Experimental results revealed that Ag-rGO and Ag-MoS2showed 99% and 80% response in photocatalytic activity. Besides, the nanocatalyst (Ag-MoS2and Ag-rGO) exhibited 6.05 mm inhibition zones againstS. aureusgram positive (G+) and 3.05 mm forE. coligram negative (G-) in antibacterial activity. To rationalize biocidal mechanism of Ag-doped MoS2NPs and Ag-rGO,in silicomolecular docking study was employed for two enzymes i.e.β-lactamase and D-alanine-D-alanine ligase B (ddlB) from cell wall biosynthetic pathway and enoyl-[acylcarrier-protein] reductase (FabI) from fatty acid biosynthetic pathway belonging toS. aureus. The present study provides evidence for the development of cost-effective, environment friendly and viable candidate for photocatalytic and antimicrobial applications.

MoS2 nanosheets were developed by undertaking the liquid-phase exfoliation of bulk counterparts. In order to enhance its photocatalytic properties, the host material was doped with p-type transition metals (i.e., Ag, Co, Bi, and Zr). The hydrothermal technique was used to produce samples doped with 7.5 wt% transition metals (TM). X-ray diffraction detected the existence of 2H-phase by mirroring its reflection at 2θ ∼ 14°, while the peak distribution revealed the degree of exfoliation in samples. Low PL intensities indicated a lower recombination of electron-hole pairs, as corroborated by a high degree of photocatalytic action. Raman analysis was undertaken to identify molecular vibrations. The A1g mode in Raman spectra consistently showed a blueshift in all samples and the E12g mode was only slightly affected, which is evidence of the p-type doping in the MoS2 nanosheets. In the XPS spectrum, two characteristic peaks of Mo 3d appeared at 229.87 and 233.03 eV assigned to Mo-3d5/2 and Mo-3d3/2, respectively. Furthermore, a microstructural examination with HR-TEM and FESEM divulged a thin-layered structure of MoS2 consisting of flat, gently curved or twisted nanosheets. Diverse morphologies were observed with a non-uniform distribution of the dopant. Photocatalytic action of the TM-doped products effectively degraded methylene blue (MB) concentrations of up to 94 percent (for Ag-MoS2). The synergistic effect of doped MoS2 nanosheets against S. aureus in comparison to E. coli bacteria was also evaluated. The efficacy % age improved from (0-31.7%) and (23.5-55.2%) against E. coli, and (0-34.2%) and (8.3-69.23%) against S. aureus. Moreover, results from first principles calculations indicate that substitutional doping of TM atoms is indeed advantageous. Theoretical calculations confirmed that doping with Ag, Co, Bi, and Zr leads to a decrease in the band gap to a certain degree, in which the conduction band edge shifts toward lower energy, while the valence band shifts closer to the high energy end. It can be concluded that Ag, Co, and Bi impurities can lead to beneficial p-type doping in MoS2 monolayered structures. With regards to doping with Zr, the acceptor levels are formed above the edge of the valence band, revealing an introduction of the p-type character.

This study compares the catalytic and antimicrobial potential of BN nanosheets doped with various transition metals-TMs (Co, Cu, Ni, Zr, and Bi). Evaluation of catalytic activity demonstrated that prepared products can be used as efficient nanocatalysts for wastewater management. TMs-doped BN depicted higher bactericidal efficacy against S. aureus compared to E. coli with molecular docking analysis. Density functional theory calculations were also performed to investigate the structural stability and electronic behavior of samples. It was found that the band gap evolution corroborates well with the experimental trends, exhibiting a diminution of the band gap value with substitutional TM atoms. Moreover, the adsorption energies of NaBH4 molecule on undoped and TMs doped BN nanosheets are investigated, in which the adsorption energy between the Co-doped BN monolayer and NaBH4 is greater compared with other doped nanosheets.

A new era in the development of advanced functional materials was partly sparked by the discovery of 2D materials. In this respect, graphene is believed to have marked the origin of 2D materials. The ability to fabricate a vast majority of such advanced nanomaterials hinges upon the strength of interplanar interactions realized in their respective bulk counterparts. The present study undertakes the comparative analysis of oft-explored 2D materials such as Dirac 2D materials (GO, rGO), TMDCs (MoS2) and 2D insulators (BN) in the context of their structural, optical, thermal and morphological parameters. Despite implementing several methodologies including a combination of physical, chemical and biological techniques, aquatic and microbial pollution remains a challenge to this day. More recently, nanomaterials have attracted considerable attention as these are believed to hold an extraordinary prospective for utilization toward environmental remediation. Among several probable candidates, 2D materials hold immense appeal due to its useful properties including high absorptivity and large surface area, which enable them to be employed for multifaceted applications. In the present study, a wide range of experimental results extracted from numerous characterization techniques (i.e., XRD, UV–Vis, FTIR, HR-TEM, XPS, DSC-TGA, and Raman) is included. For instance, optical data obtained from these materials point toward a narrow bandgap, while HR-TEM images show large surface area, which suggests that these materials hold promising prospect for use in applications that require strong catalytic activity. Further experimental results indicate that photocatalytic and sonophotocatalytic potential is significantly enhanced by 2D materials. In this respect, rGO showed 60% degradation of synthetic pollutant in 100 min and MoS2 realized 55% degradation during the same duration. The present study suggests that rGO may be used as a superior photocatalyst in wastewater treatment and related environmental applications. Moreover, the sonophotocatalytic behavior exhibited by these materials showed consistently higher efficiency compared to the respective individual processes which is attributed to the formation of larger amounts of electron–hole pairs.

Nanostructured materials incorporated with biological reducing agents have shown significant potential for use in bactericidal applications. Such materials have also demonstrated considerable efficacy to counter effects of chemical toxicity. In this study, nanostructured molybdenum disulfide (MoS2) was doped with various concentrations (2.5, 5, 7.5, 10 wt%) of zirconium (Zr) using a hydrothermal route in order to assess its antimicrobial and catalytic potential. Doped and control samples were characterized with various techniques. X-ray diffraction (XRD) analysis confirmed the presence of the hexagonal phase of MoS2 and identification of various functional groups and characteristic peaks (Mo bonding) was carried out using FTIR spectra. Micrographs obtained from FESEM and HR-TEM showed a sheet-like surface morphology, while agglomeration of nanosheets was observed upon doping with nanoparticles. To seek further clarity regarding the layered features of S-Mo-S planes, the defect densities and electronic band structure of pure MoS2 and doped MoS2 samples were investigated through Raman analysis. Optical properties of Zr-doped MoS2 nanosheets were assessed using a UV-vis spectrophotometer and the results indicated a red-shift, i.e., movement of peaks towards longer wavelengths, of the material. Dynamics of migration and recombination of excited electron-hole pairs were investigated using PL spectroscopy, which was also used to confirm the presence of exfoliated nanosheets. In addition, the synthetic dye degradation potential of pure and doped samples was investigated in the presence of a reducing agent (NaBH4). It was noted that doped MoS2 showed superior catalytic activity compared to undoped MoS2. The nanocatalyst synthesized in this study exhibited enhanced antibacterial activity against E. coli and S. aureus at high concentrations (0.5, 1.0 mg/50 μl). The present study suggests a cost-effective and environmentally friendly material that can be used to remove toxins such as synthetic dyes and tannery pollutants from industrial wastewater.

In this study, boron nitride nanosheets (BN–NS) were prepared through exfoliation of bulk BN powder and efficacious incorporation of Ni (dopant material) was achieved using hydrothermal methodology. Hexagonal phase of BN (h-BN) was detected using x-ray difractometer (XRD). The presence of used chemicals was identified by functional group analysis through fourier transform infrared spectroscope (FTIR), which indicated strong vibrations for B–N and B–N–B. Optical examination carried out through absorption spectra extracted from UV–vis. spectroscopy point out absorption at deep UV state. Raman spectra were obtained to affirm structural molecular fingerprints of BN. Excitons behavior was studied using photoluminescence (PL) spectroscope. Scanning (SEM) and transmission electron microscopes (TEM) were used to investigate morphological and microstructural features while interlayer spacing was evaluated using HRTEM micrographs. Purity of the obtained product was studied by means of EDS analysis. Catalytic activity was undertaken to inspect dye degradation which was evaluated spectrophotometrically. This study provides experimental validation to the use of two-dimensional materials, especially BN–NS, for rapid and enhanced degradation of dyes.

Nanosheets incorporated with biological reducing agents are widely used to minimize the toxic effects of chemicals. Biologically amalgamated metal oxide nanomaterials have crucial importance in nanotechnology. In this study, bare and bismuth (Bi)-doped molybdenum disulfide (MoS2) nanosheets were synthesized via a hydrothermal method. Different Bi weight ratios of 2.5, 5, 7.5 and 10% were incorporated in a fixed amount of MoS2 to evaluate its catalytic and antimicrobial activities. Doped nanosheets were characterized using XRD, FTIR and UV-vis spectroscopy, FESEM, HRTEM, Raman, PL, DSC/TGA, EDX, XRF and XPS analysis. The XRD spectra confirmed that the doped nanosheets exhibit a hexagonal structure and their crystallite size increases gradually upon doping. The morphology and interlayer d-spacing of doped MoS2 were determined by FESEM and HRTEM. The presence of functional groups in the doped nanosheets was confirmed using FTIR, PL and Raman analysis. The absorption intensity increased and the corresponding measured band gap energy decreased with doping. The thermal stability and weight loss behaviour of the prepared samples were studied using DSC/TGA. The doped MoS2 nanosheets showed a higher catalytic potential compared to undoped MoS2. The doped Bi nanosheets exhibited higher antimicrobial activity against Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) at different concentrations of Bi (0.075 and 0.1), showing a tendency to counter the emerging drug resistance against pathogenic bacterial diseases. Consequently, significant inhibition zones were recorded against (MDR) S. aureus ranging from 2.25 to 3.3 mm and 3.25 to 5.05 mm at low and high concentrations of doped-Bi nanosheets and against Gram-negative E. coli ranging from 1 to 1.45 mm at high concentrations. In conclusion, the Bi-doped MoS2 nanocomposite has exhibited significant potential for use in industrial dye degradation applications. Its antibacterial properties can also mitigate health risks associated with the presence of several well-known pathogens in the environment.

The objective of this study is to analyze the effects of zirconium (Zr) and silver (Ag) doping on the photoactivity of titania (TiO2). Zr-Ag (ZA) co-doped TiO2 products were fabricated via sol-gel technique and their properties (structural and chemical) were characterized. The weight ratio of TiO2 was fixed, while weight ratios of Zr and Ag were varied from 2 to 4, 6 and 8 wt% while synthesized samples were calcined at 400 degrees C for 3 h. The XRD results demonstrated that the incorporation of metal doping agents failed to alter the host material's lattice structure, however, its crystallite size was reduced from 13.54 to 5.05 nm with increasing Zr4+ and Ag+ concentrations. FTIR spectroscopy was used to examine various functional groups. In the attained spectra, an ample absorption peak between 500 and 1000 cm(-1) was recorded, which was ascribed to Ti-O-Ti linkage vibration mode present within TiO2. Surface morphology, microstructure, SAED patterns and elemental composition were examined with FE-SEM, HR-TEM and EDX, which served to confirm the ZA-doped TiO2 product. Band gap energy of the co-doped material was significantly reduced as indicated by a higher wavelength redshift in the spectra. The photoactivity and kinetics of photo-products were investigated by observing photo-decolorization of methylene blue (MB) under a radiation source. Photodecomposition of MB was dramatically enhanced when titania co-doped with Zr and Ag was employed compared to un-doped or mono-doped TiO2. The ZA (8 wt%) co-doped TiO2 photocatalyst depicted the maximum MB removal efficiency (similar to 93%) within 90 min under a light source.