Ag2MoO4 nanoparticles encapsulated in g-C3N4 for sunlight photodegradation of pollutants

Acyclovir contamination in environment: Occurrence, transformation, toxicity, risk, and evaluation as a pharmaceutical indicator

Acyclovir (ACV), a widely used antiviral medication effective against herpes simplex viruses (HSV), is raising concern due to its pervasive presence in global water and the associated potential risks. ACV can undergo transformation under varying conditions, leading to the generation of diverse transformation products that may exhibit heightened toxicity. This review aims to present a comprehensive overview of the environmental impact of ACV. We compile data on ACV concentrations in different water sources worldwide to shed light on its global prevalence. The levels of ACV detected in both wastewater and natural water sources generally remain at low concentrations, typically in the range of ng L-1 level. ACV poses minimal threats to aquatic organisms and humans in comparison to its transformation products, and conventional wastewater treatment methods utilizing biological processes can reduce ACV concentrations, yet only achieve transformation rather than complete elimination of risks, as the intermediates often demonstrate elevated toxicity levels and increased persistence. Additionally, perspectives are proposed to inspire future research on risk assessment of ACV, its intermediates and other pharmaceuticals. Given the challenges in keeping pace with the proliferation of chemical varieties, prioritizing and optimizing risk assessment methodologies is imperative. To this end, the suitability of ACV indicators is evaluated by summarizing data across diverse water bodies.

Fundamentals of Flexoelectricity, Materials and Emerging Opportunities Toward Strain-Driven Nanocatalysts

Flexoelectricity, an intrinsic property observed in materials under nonuniform deformation, entails a coupling between polarization and strain gradients. Recent catalyst advancements have reignited interest in flexoelectricity, particularly at the nanoscale, where pronounced strain gradients promote robust flexoelectric effects. This paper comprehensively examines flexoelectricity, encompassing methodologies for precise measurement, elucidating its distinctions from related phenomena, and exploring its potential applications in augmenting catalytic properties. So far, the greatest potentials are based on lead strontium titanate (PST) and other metallic titanates such as titania (TiO2), strontium titanate (STO), barium strontium titanate (BST) sulfates (MoS2, ZnS) and halide perovskites (with archetype XPbI3). This review explores the promise of flexoelectric properties in addressing material and photocatalytic challenges, such as charge carrier recombination and ineffective surface charge separation. Additionally, it sheds light on the synergy with emerging paradigms like photo-flexo catalysis and synergistic flexo-piezo catalysis, specifically focusing on selective chemical transformations like green hydrogen production. Current limitations related to the usage of photoflexoelectricity for photocatalysis are mostly the stability of the used substance (susceptibility to photodegradation) or the voltage values, which represent the inferior potential for specific practical applications. This work underscores the indispensable role of flexoelectricity in catalysis and its capacity to steer future research and technological advancement.

Enzyme-Like Photocatalytic Octahedral Rh/Ag2MoO4 Accelerates Diabetic Wound Healing by Photo-Eradication of Pathogen and Relieving Wound Hypoxia

The harsh environment of diabetic wounds, including bacterial infection and wound hypoxia, is not conducive to wound healing. Herein, an enzyme-like photocatalytic octahedral Rh/Ag2MoO4 is developed to manage diabetic-infected wounds. The introduction of Rh nanoparticles with catalase-like catalytic activity can enhance the photothermal conversion and photocatalytic performance of Rh/Ag2MoO4 by improving near-infrared absorbance and promoting the separation of electron-hole pairs, respectively. Rh/Ag2MoO4 can effectively eliminate pathogens through a combination of photothermal and photocatalytic antibacterial therapy. After bacteria inactivation, Rh/Ag2MoO4 can catalyze hydrogen peroxide to produce oxygen to alleviate the hypoxic environment of diabetic wounds. The in vivo treatment effect demonstrated the excellent therapeutic performance of Rh/Ag2MoO4 on diabetic infected wounds by removing infectious pathogens and relieving oxygen deficiency, confirming the potential application of Rh/Ag2MoO4 in the treatment of diabetic infected wounds.

Recent advances in photocatalytic removal of antiviral drugs by Z-scheme and S-scheme heterojunction

The possible impact of antivirals on ecosystems and the emergence of antiviral resistance are the reasons for concern about their environmental release. Consequently, there has been a significant increase in curiosity regarding their presence in both organic and synthetic systems in recent years. The primary objective of this review is to address the void of information regarding the global presence of antiviral drugs in both wastewater and natural water sources. Photocatalytic degradation of pollutants is an eco-friendly, cost-effective method that effectively addresses environmental degradation. The development of efficient photocatalysts remains a significant issue in accelerating the degradation of pollutants, especially when employing solar light. Thus, the development of Z-scheme and S-scheme semiconductor heterojunctions has emerged as a viable method to improve light absorption and enhance the redox capability of photocatalysts. The principles of Z-scheme and S-scheme are reviewed extensively. The degradation route and occurrence of antiviral are discussed briefly. Finally, a short preview of the degradation of antiviral using Z-scheme and S-scheme is also highlighted.

Recent progress and prospect of graphitic carbon nitride-based photocatalytic materials for inactivation of Microcystis aeruginosa

The proliferation of harmful algal blooms is a global concern due to the risk they pose to the environment and human health. Algal toxins which are hazardous compounds produced by dangerous algae, can potentially kill humans. Researchers have been drawn to photocatalysis because of its clean and energy-saving properties. Graphite carbon nitride (g-C3N4) photocatalysts have been extensively studied for their ability to eliminate algae. These photocatalysts have attracted notice because of their cost-effectiveness, appropriate electronic structure, and exceptional chemical stability. This paper reviews the progress of photocatalytic inactivation of harmful algae by g-C3N4-based materials in recent years. A brief overview is given of a number of the modification techniques on g-C3N4-based photocatalytic materials, as well as the process of inactivating algal cells and destroying their toxins. Additionally, it provides a theoretical framework for future research on the eradication of algae using g-C3N4-based photocatalytic materials.

Recent Developments in Semiconductor-Based Photocatalytic Degradation of Antiviral Drug Pollutants

The prevalence of antiviral drugs (ATVs) has seen a substantial increase in response to the COVID-19 pandemic, leading to heightened concentrations of these pharmaceuticals in wastewater systems. The hydrophilic nature of ATVs has been identified as a significant factor contributing to the low degradation efficiency observed in wastewater treatment plants. This characteristic often necessitates the implementation of additional treatment steps to achieve the complete degradation of ATVs. Semiconductor-based photocatalysis has garnered considerable attention due to its promising potential in achieving efficient degradation rates and subsequent mineralization of pollutants, leveraging the inexhaustible energy of sunlight. However, in recent years, there have been few comprehensive reports that have thoroughly summarized and analyzed the application of photocatalysis for the removal of ATVs. This review commences by summarizing the types and occurrence of ATVs. Furthermore, it places a significant emphasis on delivering a comprehensive summary and analysis of the characteristics pertaining to the photocatalytic elimination of ATVs, utilizing semiconductor photocatalysts such as metal oxides, doped metal oxides, and heterojunctions. Ultimately, the review sheds light on the identified research gaps and key concerns, offering invaluable insights to steer future investigations in this field.

Evaluation of acyclovir adsorption on granular activated carbon from aqueous solutions: batch and fixed-bed parametric studies

The present study is aimed to assess the adsorptive potential of carbonaceous material for the acyclovir (ACVR) removal from the aquatic environment using batch and fixed-bed processes. In batch mode, the impact of various process conditions (contact time, pH, adsorbent dose, initial ACVR concentration, and temperature) on ACVR adsorption was investigated. Experimental results revealed that Langmuir isotherm and the pseudo-second-order kinetic model adequately represent the ACVR adsorption mechanism, indicating homogeneous adsorption. The process was found exothermic and spontaneous. Thermodynamic studies concluded that adsorption is a result of both physisorption and chemisorption. To understand the dynamic regime for the design of large-scale column studies, experimental data obtained from breakthrough curve were fitted to various analytical kinetic models. Yan model followed by Thomas model demonstrated a greater correlation of breakthrough data, confirming that the results are significant and are in line with Langmuir isotherm and pseudo-second-order kinetic. G-AC exhibits sufficient adsorption capacity for ACVR. Hence, it is concluded that it can be used in a fixed-bed column in continuous mode for the treatment of ACVR-contaminated wastewater.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s11696-023-02810-7.

In-situ synthesis of novel dual S-scheme AgI/Ag6Mo7O24/g-C3N4 heterojunctions with tandem structure for photocatalytic degradation of organic pollutants

The controllable design of multivariate heterojunction with sequential structures is of significant relevance for breaking the performance limit of binary composite photocatalysts. In this work, the novel dual S-scheme ternary-component AgI/Ag₆Mo₇O₂₄/exfoliated g-C₃N₄ (ECN) composite was prepared by a two-step in-situ synthetic strategy. The energy band bending at the heterointerface and the formation of dual built-in electric field could be observed due to distinct work functions of different components in the ternary composite. Benefiting from the sequential heterojunction structure, the AgI/Ag₆Mo₇O₂₄/ECN composite achieved 98.7% removal efficiency of 2-nitrophenol (2-NP) within 70 min under visible light irradiation, and AgI/Ag₆Mo₇O₂₄/ECN also showed higher degradation efficiency for a variety of organic pollutants such as methylene blue (MB), rhodamine B (RhB), methyl orange (MO), 4-nitrophenol (4-NP), 2-sec-butyl-4,6-dinitrophenol (DNBP) and tetracycline (TC). Notably, •OH and •O₂^- played dominant roles in the AgI/Ag₆Mo₇O₂₄/ECN set up, which was consistent with the dual S-scheme charge transfer mechanism. In-depth insights for the photodegradation of 2-NP were presented based on a combined DFT study and GC-MS analysis. Additionally, the photoreduction of Ag⁺ in AgI/Ag₆Mo₇O₂₄/ECN was also evaded by the fast transfer of photogenerated electrons through the dual S-scheme pathway, achieving the effect of killing two birds with one stone.

Antibacterial Z-scheme ZnIn2S4/Ag2MoO4 composite photocatalytic nanofibers with enhanced photocatalytic performance under visible light

Considering the biocompatibility of natural proteins and the strong photo-redox capability of Z-scheme heterojunctions, we fabricated Z-scheme ZnIn₂S₄/Ag₂MoO₄@Zein (Z ZA) photocatalytic membranes via electrospinning and in-situ precipitation for enrofloxacin (ENR) degradation. Z ZA exhibit a fiber structure wrapped with ZnIn₂S₄/Ag₂MoO₄ heterojunctions. Photocatalytic studies and various characterization results certified that the Z-scheme structure between ZnIn₂S₄ and Ag₂MoO₄ significantly increases the lifetime and separation efficiency of photogenerated carriers, which in turn enhances the photodegradation of ENR. The degradation rate of Z ZA-10 (ZnIn₂S₄/10 wt% Ag₂MoO₄@Zein) with the highest catalytic activity could reach 100% within 120 min compared with other samples. For ENR degradation, •O₂^- radicals were certified to be the primary active species by trapping experiments, and several possible conversion pathways of ENR in photocatalytic reactions were proposed. Furthermore, the antibacterial rates of Z ZA-20 (ZnIn₂S₄/20 wt% Ag₂MoO₄@Zein) against B. subtilis, P. aeruginosa, S. aureus, and E. coli could reach 90.09%, 89.78%, 84.34%, and 95.31%, respectively. Antibacterial evaluations and cytotoxicity assays demonstrated that Z ZA photocatalytic films had desirable antibacterial properties and low cytotoxicity, rendering them safe and effective for use in the treatment of antibiotic wastewater.

Carbon nitride-based Z-scheme heterojunctions for solar-driven advanced oxidation processes

Solar-driven advanced oxidation processes (AOPs) via direct photodegradation or indirect photocatalytic activation of typical oxidants, such as hydrogen peroxide (H₂O₂), peroxymonosulfate (PMS), and peroxydisulfate (PDS), have been deemed to be an efficient technology for wastewater remediation. Artificial Z-scheme structured materials represent a promising class of photocatalysts due to their spatially separated charge carriers and strong redox abilities. Herein, we summarize the development of metal-free graphitic carbon nitride (g-C₃N₄, CN)-based direct and indirect Z-scheme photocatalysts for solar-driven AOPs in removing organic pollutants from water. In the work, the classification of AOPs, definition and validation of Z-schemes are summarized firstly. The innovative engineering strategies (e.g., morphology and dimensionality control, element doping, defect engineering, cocatalyst loading, and tandem Z-scheme construction) over CN-based direct Z-scheme structure are then examined. Rational design of indirect CN-based Z-scheme systems using different charge mediators, such as solid conductive materials and soluble ion pairs, is further discussed. Through examining the relationship between the Z-scheme structure and activity (charge transfer and separation, light absorption, and reaction kinetics), we aim to provide more insights into the construction strategies and structure modification on CN-based Z-schemes towards improving their catalytic performances in AOPs. Lastly, limitations, challenges, and perspectives on future development in this emerging field are proposed.

Fluorescent graphitic carbon nitride with photocatalytic oxidase-like activity for anti-counterfeiting application

Herein bulk phenyl- and carbon-modified graphitic carbon nitride (PCCN) powders with tunable fluorescent emission from green-color to yellow-color were prepared by copolymerization of 2,4-diamino-6-phenyl-1,3,5-triazine and 2,2,6-triaminopyrimidine. The corresponding nanosheets with blue-color to green-color fluorescence were obtained by the oxidation of their bulk powders in sulfuric or nitric acid and then ultrasonic exfoliation. The typical PCCN_0.6 nanosheets not only displayed strong green-color fluorescence but also exhibited photocatalytic oxidase-like activity, which can catalyze the oxidation of substrates 3,3',5,5'-tetramethylbenzidine and Amplex UltraRed by O₂ to produce blue-color colorimetric product and pink-color fluorescent product, respectively. By taking advantage of green-color fluorescence and photocatalytic activity of PCCN_0.6 nanosheets, a prototype for high-level anti-counterfeiting application was demonstrated by using the mixture of PCCN_0.6 nanosheets and Amplex UltraRed as the fluorescent ink.

Plastic optical fibres applied on the photocatalytic degradation of phenol with Ag2MoO4 and ß-Ag2MoO4/Ag3PO4 under visible light

In this study, plastic optical fibre (POF) was considered as a light-transmitting medium and substrate for use in a photocatalytic environmental purification system, using Ag₂MoO₄ and β-Ag₂MoO₄/Ag₃PO₄ as photocatalysts. Pure Ag₂MoO₄ and a β-Ag₂MoO₄/Ag₃PO₄ composite were synthesized using a facile precipitation method. The composition, structures and optical properties of as-prepared catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), field-emission scanning electron microscopy (FESEM), UV/Vis diffuse reflectance spectroscopy (UV/Vis DRS), BET surface area and TGA/DTG. The catalysts were immobilized on POF and on the glass reactor surface and their efficiency in the phenol degradation was evaluated in a batch reactor under visible light. The use of POF offers advantages such as ease of handling and good adherence characteristics to support Ag₂MoO_4. The photoactivity follows the order β-Ag₂MoO₄/Ag₃PO₄ ≅ Ag₂MoO₄> TiO₂ P25, for photocatalysts immobilized on the glass reactor surface or in aqueous suspension. The immobilization of Ag₂MoO₄ on POF revealed that thinner Ag₂MoO₄ coatings achieved faster pollutant removal rates from solution, and the optimal catalyst deposition is 0.64 mg/cm², causing maximum the light penetration and electron-hole generation close to the solid-liquid interface.

Metal-organic frameworks derived C/TiO2 for visible light photocatalysis: Simple synthesis and contribution of carbon species

A series of in-situ carbon-doped TiO₂ (C_x/TiO₂) composites with a porous and crystalline structure were successfully synthesized via one-step and low-temperature calcination of titanium metal-organic framework (MOF), MIL-125(Ti). The resultant materials were comprehensively investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), N₂ adsorption-desorption measurements, UV-vis diffuse reflectance spectrum (DRS), photoluminescence (PL) spectra and photoelectrochemical measurements, and their photocatalytic activities for bisphenol A (BPA) degradation were assessed. Compared with the benchmark TiO₂ photocatalyst (P25), the C_x/TiO₂ composite material with high specific surface, lower band gap, and reduced photogenerated electron hole ratio exhibited outstanding photodegradation activity and durability for BPA, which could be attributed to the combined effect of co-doping of multiple carbon species (substituent carbon and carbonate) and porous structure. During BPA degradation, the holes and superoxide radicals were the primary role oxidative species in the reaction process. Therefore, this new efficient photocatalyst is promising candidate for photodegradation of organic pollutants.

A facile synthesis of nano AgBr attached potato-like Ag2MoO4 composite as highly visible-light active photocatalyst for purification of industrial waste-water

In recent times, silver (Ag) based semiconductors have been gained a lot of attention as photocatalysts for industrial waste-water treatment owing to their strong visible-light absorbing capability and small bandgap energy. Therefore, herein, we have designed and utilized a one-pot hydrothermal approach to the synthesis of nano-sized AgBr covered potato-like Ag₂MoO₄ composite photocatalysts for the elimination of organic wastes from the aquatic environment. To achieve a high-performance photocatalyst, a sequence of AgBr/Ag₂MoO₄ composites were acquired with varying CTAB from 1 to 4 mmol. Furthermore, the photocatalytic activity of these photocatalysts was confirmed from decomposing of Rhodamine B (RhB) dye via visible-light elucidation. It can be noticed that AgBr/Ag₂MoO₄ composites exhibited significantly increased photocatalytic behaviour as compared with pure AgBr and Ag₂MoO₄. Surprisingly, the AgBr/Ag₂MoO₄ composite obtained from 2 mmol CTAB was eliminated the entire RhB dye with 25 min. Also, the recycling experiment indicates the AgBr/Ag₂MoO₄ composite has an excellent photo-stability. Accordingly, the as-acquired AgBr/Ag₂MoO₄ composite would be a suitable photocatalytic material for industrial waste-water purification.

Fabrication of a novel ternary heterojunction composite Ag2MoO4/Ag2S/MoS2 with significantly enhanced photocatalytic performance

A novel ternary heterojunction Ag₂MoO₄/Ag₂S/MoS₂ was successfully fabricated via a facile two-step method. The prepared ternary heterojunction showed much enhanced catalytic activity compared with monomers and binary heterojunctions.

Investigations of Carbon Nitride-Supported Mn3O4 Oxide Nanoparticles for ORR

Earth-abundant Mn-based oxide nanoparticles are supported on carbon nitride using two different immobilization methods and tested for the oxygen reduction reaction. Compared to the metal free CN, the immobilization of Mn oxide enhances not only the electrocatalytic activity but also the selectivity towards the 4e- reduction reaction of O2 to H2O. The XPS analysis reveals the interaction of the pyridine N species with Mn3O4 nanoparticles being particularly beneficial. This interaction is realized—although to a limited extent—when preparing the catalysts via impregnation; via the oleic acid route it is not observed. Whilst this work shows the potential of these systems to catalyze the ORR, the main limiting factor is still the poor conductivity of the support which leads to overpotential.

Facet-, composition- and wavelength-dependent photocatalysis of Ag2MoO4

Faceted β-Ag2MoO4 microcrystals are prepared by controlled nucleation and growth in diethylene glycol (DEG) or dimethylsulfoxide (DMSO). Both serve as solvents for the liquid-phase synthesis and surface-active agents for the formation of faceted microcrystals. Due to its reducing properties, truncated β-Ag2MoO4@Ag octahedra are obtained in DEG. The synthesis in DMSO allows avoiding the formation of elemental silver and results in β-Ag2MoO4 cubes and cuboctahedra. Due to its band gap of 3.2 eV, photocatalytic activation of β-Ag2MoO4 is only possible under UV-light. To enable β-Ag2MoO4 for absorption of visible light, silver-coated β-Ag2MoO4@Ag and Ag2(Mo0.95Cr0.05)O4 with partial substitution of [MoO4]2- by [CrO4]2- were prepared, too. The photocatalytic activity of all the faceted microcrystals (truncated octahedra, cubes, cuboctahedra) and compositions (β-Ag2MoO4, β-Ag2MoO4@Ag, β-Ag2(Mo0.95Cr0.05)O4) is compared with regard to the photocatalytic decomposition of rhodamine B and the influence of the respective faceting, composition and wavelength.

Energy capture from thermolytic solutions and simulated sunlight coupled with hydrogen peroxide production and wastewater remediation

A novel solar salinity energy nexus was developed by combining a photocatalytic fuel cell (PFC) and a reverse electrodialysis (RED). The hybrid cell (called a PRC) can effectively transfer the solar energy and salinity gradient energy (which is regenerated by low grade industrial waste heat) to electrical energy coupled with enhanced pollutant (Rhodamine B, RhB) degradation and H₂O₂ production. Energy-Environment win-win will be realized. The open circuit voltage of the PRC was the sum of those of the PFC and the RED, and the RED stack made the larger contribution to the electricity production of PRC. The bias voltage generated from the RED stack accelerated the separation of photo-induced holes and electrons on the three-dimensional TiO₂ array photoanode, which enhanced RhB degradation and H₂O₂ production. The flow rate and concentration of the working fluids (ammonium bicarbonate) and the reaction conditions in the electrode chambers had substantial effects on the PRC performance. Under the optimal condition, the peak power density and energy efficiency of PRC reached 1500 mW m^-2 and 4.21% respectively. The performance of PRC on electricity production is better than photocatalytic electrolytic cell driven by desalination(PFCD), but not good as microbial reverse electrodialysis electrolysis cell (MREC).

Unvealing the role of β-Ag2MoO4 microcrystals to the improvement of antibacterial activity

Crystal morphology with different surfaces is important for improving the antibacterial activity of materials. In this experimental and theoretical study, the antibacterial activity of β-Ag₂MoO₄ microcrystals against the Gram-positive bacteria, namely, methicillin-resistant Staphylococcus aureus (MRSA), and the Gram-negative bacteria, namely, Escherichia coli (E. coli), was investigated. In this study, β-Ag₂MoO₄ crystals with different morphologies were synthetized by a simple co-precipitation method using three different solvents. The antimicrobial efficacy of the obtained microcrystals against both bacteria increased according to the solvent used in the following order: water < ammonia < ethanol. Supported by experimental evidence, a correlation between morphology, surface energy, and antibacterial performance was established. By using the theoretical Wulff construction, which was obtained by means of density functional calculations, the morphologies with large exposition of the (001) surface exhibited superior antibacterial activity. This study provides a low cost route for synthesizing β-Ag₂MoO₄ crystals and a guideline for enhancing the biological effect of biocides on pathogenic bacteria by the morphological modulation.

Novel carbon and defects co-modified g-C3N4 for highly efficient photocatalytic degradation of bisphenol A under visible light

Graphite carbon nitride (g-C₃N₄, CN) is considered as a promising semiconductor for environmental catalysis. However, pure CN can not meet the requirements for actual applications due to its high recombination rate of photogenerated electron-hole pairs and a relatively large band gap preventing full utilization of solar energy. In this work, we report synthesis of a novel carbon and defects co-modified g-C₃N₄ (C_xCN) by calcination of melamine activated by oxalic. This new catalyst C_xCN has porous structure with much higher surface areas compared with pristine CN. UV-vis analysis and DFT calculations show that C_xCN has a lower bandgap for enhancing visible light adsorption compared with CN. Photoluminescence (PL) and photoelectrochemical analyses show that C_xCN has a low recombination rate of photogenerated electron-hole pairs, which improves the utilization of solar energy. As a result, C_xCN samples show high efficiency for the degradation of bisphenol A (BPA) under visible light irradiation, where the best catalyst of C_xCN (C_1.0CN) samples shows about 22 times higher photocatalytic degradation rate than that of CN. Moreover, C_1.0CN shows high mineralization rate and can degrade BPA into CO₂ and H₂O by the generated active species, like superoxide radicals (O₂^-) and holes (h⁺).

Facile synthesis of new polyhedron-like WO3/butterfly-like Ag2MoO4 p–n junction photocatalysts with higher photocatalytic activity in UV/solar region light

A series of novel efficient polyhedron-like WO₃/butterfly-like Ag₂MoO₄ p–n junction photocatalysts (denoted as AMW-x) were designed and synthesized.

In Situ Synthesis, Characterization, and Catalytic Performance of Polypyrrole Polymer-Incorporated Ag2MoO4 Nanocomposite for Detection and Degradation of Environmental Pollutants and Pharmaceutical Drugs

Material combinations of semiconductor with conducting polymer are gaining growing interest due to their enhanced activities in photocatalysis as well as electrochemical sensing. In this present work, we report a facile in situ synthesis of polypyrrole (PPy) polymer-incorporated silver molybdate (Ag₂MoO₄) nanocomposite that is utilized as a photocatalyst and electrocatalyst for the degradation of pollutant heavy metals, namely, methylene blue (MB) and heavy metal (Cr(VI)), and ciprofloxacin (CIP) and for detection of the drug, azomycin. The synthesized nanocomposite was characterized by various theoretical, spectral, and microscopic studies. Matching of the powder X-ray diffraction pattern with JCPDS no. 76-1747 confirmed the formation of α-Ag₂MoO₄/PPy. The surface topography and spherical morphology of the nanocomposite were studied using field emission-scanning electron microscopy and transmission electron microscopy. Fourier transform infrared spectral detail expounds the smooth incorporation of PPy to Ag₂MoO₄. The as-synthesized nanocomposite performs as an efficient photocatalyst in the degradation of MB (99.9%), Cr(VI) (99%), and CIP drug (99.8%) within 10 min. In addition to this, the Ag₂MoO₄/PPy-modified glassy carbon electrode (GCE) demonstrated excellent electrocatalytic activity in terms of a higher cathodic peak current and lower peak potential when compared with other modified and unmodified GCEs for the detection of azomycin. The Ag₂MoO₄/PPy/GCE displayed a broader linear response range and lower detection limit of 0.5-499 μM and 65 nM, respectively. Moreover, other potentially co-interfering compounds, such as a similar functional group-containing biological substances and inorganic species, have no interference effect toward azomycin sensing.

The effective photocatalysis and antibacterial properties of AgBr/Ag2MoO4@ZnO composites under visible light irradiation

A novel Z-scheme AgBr/Ag₂MoO₄@ZnO photocatalyst was fabricated via a hydrothermal process and in situ growth method. X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy were used to determine the structure of the photocatalyst. The results showed that the composites were tightly connected by the (101) lattice plane of ZnO, the (222) plane of Ag₂MoO₄ and the (200) lattice plane of AgBr. Because of the strong redox activity and good separability of photoelectrons and holes induced by the Z-scheme structure, the photodegradation rate for ciprofloxacin (CIP) solution was 80.5% by the photocatalysis of 0.5 AgBr/Ag₂MoO₄@ZnO. In addition, more than 99.999% of Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa cells were killed within 60 min. These results demonstrate that AgBr/Ag₂MoO₄@ZnO is a promising photocatalyst, which can be used in organic pollutant degradation and the photocatalytic antibacterial area.

Graphene Oxide/BiOCl Nanocomposite Films as Efficient Visible Light Photocatalysts

A novel graphene oxide/BiOCl (GO/BiOCl) nanocomposite film was prepared via a spread coating method. In visible-light photocatalytically degrading Rhodamine B (RhB) experiments, 2 wt% GO/BiOCl could degrade 99% of RhB within 1.5 h and the rate constant was 12.2 times higher than that of pure BiOCl. The degradation efficiency still kept at 80% even after 4 recycles, evidencing the relatively good recyclability. The enhancement was attributed to the improvement of visible light adsorption and charge separation. Holes and superoxide radicals· O2- played a major role as reactive species. The values of conduction band and valence band for GO and BiOCl were calculated and a new photocatalytic mechanism of GO/BiOCl nanocomposite was proposed.

Facile Fabrication of BiOI/BiOCl Immobilized Films With Improved Visible Light Photocatalytic Performance

HIGHLIGHTS

A facial method was used to fabricate BiOI/BiOCl film at room temperature.

30% BiOI/BiOCl showed an excellent photocatalytic activity and stability.

Improvement of photocatalytic activity was owed to expanded visible light absorption and high separation efficiency of charge.

Photocatalysis has been considered to be one of the most promising ways to photodegrade organic pollutants. Herein, a series of BiOI/BiOCl films coating on FTO were fabricated through a simple method at room temperature. The photocatalytic efficiency of 30%BiOI/BiOCl could reach more than 99% aiming to degrading RhB and MB after 90 and 120 min, respectively. Compared with BiOCl, 30%BiOI/BiOCl showed 12 times higher efficiency when degrading RhB. In comparison with BiOI, 30%BiOI/BiOCl showed 5 and 6 times higher efficiency when degrading RhB and MB, respectively. These obvious enhancements were attributed to expanded visible light absorption and high separation performance of photoinduced charge. Moreover, the photocatalytic activity of 30%BiOI/BiOCl had no obvious decrease after five recycles, suggesting that it was a promising photocatalyst for the removal of MB and RhB pollutants. Finally, the possible growth process for the BiOI/BiOCl thin films and photocatalysis mechanism were investigated in details. This work would provide insight to the reasonable construction of BiOX heterojunction and the photocatalytic mechanism in degrading organic pollutants.