Facile fabrication of a direct Z-scheme Ag2CrO4/g-C3N4 photocatalyst with enhanced visible light photocatalytic activity

Construction of a novel double S-scheme structure WO3/g-C3N4/BiOI: Enhanced photocatalytic performance for antibacterial activity

In recent years, the threat to human health from bacteria in wastewater has attracted attention, and photocatalytic technology has emerged as a promising strategy for inactivating bacteria in water. Therefore, it is of great research value to develop a novel high-efficiency photocatalytic system with the visible light response. We successfully designed a double S-scheme heterojunction composite WO₃/g-C₃N₄/BiOI (WCB) in this paper. The preparation of WCB composites was demonstrated by a series of characterizations, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM). The antibacterial effects of photocatalysts against representative Gram-negative strain Escherichia coli (E. coli) and Gram-positive strain Staphylococcus aureus (S. aureus) were tested under LED light irradiation. The novel photocatalyst presented excellent antibacterial properties, inactivating E. coli in 12 min and S. aureus in 20 min. The bacterial cell inactivation process was studied by scanning electron microscopy (SEM) and Confocal Laser Scanning Microscopy (CLSM). Active species capture experiments show that the active species present in the WCB composites in the process of inactivating bacteria are h⁺, e^-, OH and O₂^-. In conclusion, the synthesized double S-scheme WCB photocatalyst exhibits remarkable photocatalytic antibacterial activity under LED light and has broad prospects for practical application in water antibacterial treatment.

Facile Construction of Bi2Sn2O7/g-C3N4 Heterojunction with Enhanced Photocatalytic Degradation of Norfloxacin

To mitigate antibiotic residues in the water environment, Bi2Sn2O7/g-C3N4 (BSCN) heterojunction was fabricated by a facile ultrasound-assisted hydrothermal method. The microstructure, morphology, and optical properties of Bi2Sn2O7/g-C3N4 heterojunction was studied by XRD, FTIR, XPS, SEM, TEM, UV–Vis DRS, and PL. The degradation rate of 20 mg/L norfloxacin (NOR) under visible light for 3 h was adopted as one of the indexes to evaluate the photocatalytic performance of Bi2Sn2O7/g-C3N4 heterojunction. Embellished with 20% Bi2Sn2O7 (BSO), the Bi2Sn2O7/g-C3N4 heterojunction decomposed 94% NOR in the experimental solution, which was 2.35 and 3.03 times as much as pristine g-C3N4 and bare Bi2Sn2O7, respectively. In addition, the Bi2Sn2O7/g-C3N4 heterojunction still eliminated 89% of NOR after five cycles, portending outstanding stability and cyclability of photocatalytic activity. A possible photocatalytic mechanism of Bi2Sn2O7/g-C3N4 heterojunction for NOR degradation is proposed.

Visible-light photocatalysis of Ag-doped graphitic carbon nitride for photodegradation of micropollutants in wastewater

This work reports on graphitic carbon nitride (C₃N₄) modified with silver to investigate its visible-light-driven photocatalysis for decomposition of micropollutants in wastewater. Various characterization methods were conducted to examine the physico-chemical properties of Ag-doped C₃N₄ (Ag-C₃N₄) photocatalyst. The results from structural, morphological, and surface chemical analysis indicated that C₃N₄ was successfully doped with Ag. Photoluminescence and transient photocurrent density studies revealed that the recombination rate of electron-hole pairs was reduced, leading to the enhancement of photocatalytic activities of the photocatalyst. Ag-C₃N₄ showed high photocatalytic performance for photodegradation of our target micropollutant, bisphenol A (BA). It could completely remove BA in 1 h with kinetic constant 6.2 times higher than that of the undoped C₃N₄ photocatalyst. Recycling test and the assessment of the photocatalyst in wastewater further confirmed the excellent stability and applicability of the Ag-C₃N₄ photocatalyst. This work could provide a new solution to the practical application of photocatalyts for the degradation of micropollutants in wastewater.

Ultrasound-Assisted Hydrothermal Synthesis of SrSnO3/g-C3N4 Heterojunction with Enhanced Photocatalytic Performance for Ciprofloxacin under Visible Light

In this work, an SrSnO3/g-C3N4 heterojunction with different dosage of SrSnO3 was fabricated by an ultrasound-assisted hydrothermal approach and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-visible diffuse reflectance spectra (UV-Vis DRS), and photoluminescence spectroscopy (PL). Ciprofloxacin was adopted to assess the degradation performance, and the sample combined with 40% SrSnO3 eliminated 93% of ciprofloxacin (20 mg/L) within 3 h under visible light, which is 6.6 and 1.7 times greater than for SrSnO3 and g-C3N4, respectively. Furthermore, 85% CIP was extinguished after five cycles of a photocatalytic process. Ultimately, a possible photocatalytic mechanism was dissected.

The Synthesis of h-BN-Modified Z-Scheme WO3/g-C3N4 Heterojunctions for Enhancing Visible Light Photocatalytic Degradation of Tetracycline Pollutants

The photocatalytic performance of common photocatalysts is limited by their low surface area, insufficient absorption of light energy, and fast photogenerated electron-hole recombination rate. The introduction of Z-scheme photocatalysts decorated with hexagonal boron nitride (h-BN) has already been confirmed to be an effective way to extend the surface area and increase the charge separation, thereby enhancing the photocatalytic performance. In this study, a hexagonal boron nitride (h-BN)-decorated WO₃/g-C₃N₄ heterojunction photocatalyst was successfully synthesized via an in situ method using tungstic acid, melamine, and hexagonal boron nitride as the precursors. The physical and chemical properties of the resulting samples were thoroughly characterized. The surface, morphological, and optical properties of the resulting materials were thoroughly characterized by XRD, XPS, SEM, TEM, UV-vis DRS, BET surface areas, PL, and ESR analysis. The WO₃/g-C₃N₄/BN composite exhibited a much higher photocatalytic activity for tetracycline degradation under visible light irradiation than pure g-C₃N₄, WO₃, and BN. The favorable photocatalytic activity of WO₃/g-C₃N₄/BN composites can be ascribed to the increased surface area and enhanced separation efficiency of photogenerated electron-hole pairs by adding h-BN nanosheets and forming the WO₃/g-C₃N₄ heterojunction. This work indicates that the WO₃/g-C₃N₄/BN photocatalyst is a promising material in wastewater treatment.

Recent advancement in Bi5O7I-based nanocomposites for high performance photocatalysts

Bi₅O₇I belongs to the family of bismuth oxyhalides (BiOX, X = Cl, Br, I), having a unique layered structure with an internal electrostatic field that promotes the separation and transfer of photo-generated charge carriers. Interestingly, Bi₅O₇I exhibits higher thermal stability compared to its other BiOX member compounds and absorption spectrum extended to the visible region. Bi₅O₇I has demonstrated applications in diverse fields such as photocatalytic degradation of various organic pollutants, marine antifouling, etc. Unfortunately, owing to its wide band gap of ∼2.9 eV, its absorption lies mainly in the ultraviolet region, and a tiny portion of absorption lies in the visible region. Due to limited absorption, the photocatalytic performance of pure Bi₅O₇I is still facing challenges. In order to reduce the band gap and increase the light absorption capability of Bi₅O₇I, doping and formation of heterostructure strategies have been employed, which showed promising results in the photocatalytic performance. In addition, the plasmonic heterostructures of Bi₅O₇I were also developed to further boost the efficiency of Bi₅O₇I as a photocatalyst. Here, in this review article, we present such recent efforts made for the advanced development of Bi₅O₇I regarding its synthesis, properties and applications. The strategies for photocatalytic performance enhancement have been discussed in detail. Moreover, in the conclusion section, we have presented the current challenges and discussed possible prospective developments in this field.

Biomedical application of graphitic carbon nitrides: tissue depositionin vivo, induction of reactive oxygen species (ROS) and cell viability in tumor cells

The urgency for new materials in oncology is immediate. In this study we have developed the g-C₃N₄, a graphitic-like structure formed by periodically linked tris-s-triazine units. The g-C₃N₄has been synthesized by a simple and fast thermal process. XRD has shown the formation of the crystalline sheet with a compacted structure. The graphite-like structure and the functional groups have been shown by Raman and FTIR spectroscopy. TEM image and AFM revealed the porous composed of five or six C-N layers stacked. DRS and Photoluminescence analyses confirmed the structure with band gap of 2.87 eV and emission band at 448 nm in different wavelengths excitation conditions. The biological results showed inhibitory effect on cancer cell lines and non-toxic effect in normal cell lines. To the best of our knowledge, this is the first work demonstrating the cytotoxic effects of 2D g-C₃N₄in a cancer cell line, without any external or synergistic influence. The biodistribution/tissue accumulation showed that g-C₃N₄present a tendency to accumulation on the lung in the first 2 h, but after 24 h the profile of the biodistribution change and it is found mainly in the liver. Thus, 2D-g-C₃N₄showed great potential for the treatment of several cancer types.

Self-Powered Photoelectrochemical Aptasensor for Oxytetracycline Cathodic Detection Based on a Dual Z-Scheme WO3/g-C3N4/MnO2 Photoanode

With the high sensitivity and anti-interference provided by a dual Z-scheme structure photoanode and a two-electrode system, a high-performance self-powered photoelectrochemical (PEC) aptasensor for oxytetracycline (OTC) detection was established in this work. Graphitic carbon nitride (g-C₃N₄) with excellent photoelectric properties was used to be combined with WO₃ and MnO₂ to form a kind of dual Z-scheme heterojunction. The designed unique structure and the complementary performances of the three materials collectively guaranteed the highly stable photocurrent output of the photoanode due to the wide range of light absorption and the high separation rate of electron-hole pairs. The aptamer-based cathode modified with reduced graphene oxide (rGO) and Au nanoparticles (Au NPs) provided high conductivity and aptamer-binding sites, which brought excellent selective recognition of OTC as well as the self-powered capacity by receiving electrons from the photoanode. In the PEC sensing of OTC, the device presented a wide detection range from 1 pM to 150 nM and a low detection limit of 0.1 pM. Besides, the developed PEC aptasenor showed good selectivity, reproducibility, and stability, so as to be applied to real samples. The proposed PEC sensing method can be considered an effective and promising direction for the detection of antibiotics in the future.

Photocatalytic degradation of cephalexin by g-C3N4/Zn doped Fe3O4 under visible light

In this work, we reported synthesis of a novel magnetically separable g-C₃N₄/Zn doped Fe₃O₄ composite (g-CN/ZnFe) by a simple polyol thermal method. The characteristics of the as-prepared composite was checked by XRD, SEM, TEM, XPS, PL technologies. The optimized weight ratio of g-C₃N₄ and Zn doped Fe₃O₄ was investigated. In addition, the photocatalytic activities of the composite products were checked by degradation of Cephalexin (CEX) under visible light. The results showed that g-CN/ZnFe composite with an added 20% g-C₃N₄ exhibited the highest photocatalytic activity for cephalexin under visible light irradiation. The improved photocatalytic activity of 20% g-CN/ZnFe can be ascribed to the low combination rate of photoinduced electron/hole pairs. Especially, g-CN/ZnFe can be recovered easily by using an external magnetic field and has the high stability after six runs. These properties of the g-CN/ZnFe as-prepared composite could be a promising photocatalyst for the degradation of pharmaceutical contaminants.

Visible light-activated self-powered photoelectrochemical aptasensor for ultrasensitive chloramphenicol detection based on DFT-proved Z-scheme Ag2CrO4/g-C3N4/graphene oxide

A visible light self-powered photoelectrochemical (PEC) aptasensor based on silver chromate particles, graphitic carbon nitride nanosheets and graphene oxide sheets (Ag₂CrO₄/g-C₃N₄/GO) for the ultrasensitive detection of chloramphenicol (CAP) was reported in this work. g-C₃N₄ was considered to be the fundamental photoelectric material because of its great oxidation ability of photogenerated hole as well as excellent biocompatibility and low toxicity. However, the narrow light absorption range and rapid carrier recombination rate limit the application of pure g-C₃N₄. Herein, Ag₂CrO₄ and GO as photosensitizer were introduced to improve the photoelectric properties of g-C₃N₄. The photocurrent of the developed ternary composite was about 3 times higher than that of pristine g-C₃N₄, which proves it can be used as a suitable photoelectric active material. Moreover, the mechanism of Z-scheme electron transfer path was proved by density functional theory (DFT) calculation. The fabricated PEC aptasensor exhibited high sensitivity toward CAP with a wide liner response of 0.5 pM to 50 nM and a detection limit of 0.29 pM. The specific recognition mechanism and excellent sensing performance indicated this aptasensor could serve as a useful tool for selective and ultrasensitive CAP detection in practical analysis.

S-scheme bismuth vanadate and carbon nitride integrating with dual-functional bismuth nanoparticles toward co-efficiently removal formaldehyde under full spectrum light

It is crucial to develop more effective photocatalysts in the field of clean environment. In response, the S-scheme BiVO₄/g-C₃N₄ heterojunction modified by in situ reduced non-noble metal Bi nanoparticles was used to synergistically degrade formaldehyde under full spectral irradiation. The results, that investigated by careful characterizations and density functional theory (DFT) calculations, proved that BiVO₄/g-C₃N₄ form an S-scheme heterojunction, which can effectively improve the separation efficiency of photogenic carriers and maintain the original strong redox capability of semiconductor materials. The SPR effect of Bi elemental substance enhanced the optical response and provided more oxidative species. Thus, the photocatalytic activity of BiVO₄/Bi/g-C₃N₄ was significantly improved through their joint efforts, that the degradation efficiency of HCHO (800 ppm) for 6 h is 96.39% under 300 W Xenon lamp without filter with the pseudo-second-order rate constant of 4.16 ppm^-1·h^-1 and CO₂ selectivity of 98.41%. Surprisingly, the degradation efficiency also reached to 49.35% and 32.23% under visible and near-infrared light irradiation, respectively. Moreover, we also tested its photocatalytic decomposition effect on formaldehyde in coatings, indicating that it has a broad prospect in future coatings applications. This study may provide an expected photocatalyst, an efficient non-noble metal modified S-scheme heterojunction, to degrade volatile organic gases under a broad spectrum light.

Silver-based semiconductor Z-scheme photocatalytic systems for environmental purification

Silver-based semiconductor photocatalysts are promising materials for solving environmental and energy issues due to their strong optical absorption, excellent quantum efficiency and photoelectrochemical properties. However, the uncontrollable photocorrosion and high use cost of single silver-based semiconductor photocatalysts limit its practical application. The construction of Z-scheme photocatalytic systems that mimic natural photosynthesis can not only enhance the photocatalytic activity of silver-based semiconductor photocatalysts, but also improve their stability and reduce the use costs. This critical review concisely highlights the basic principles of Z-scheme photocatalytic systems, and discusses the construction of silver-based semiconductor Z-scheme photocatalytic systems and the roles of metallic Ag in there and summarizes the synthesis methods of silver-based semiconductor Z-scheme photocatalytic systems. Then, a series of the solar-driven applications are elaborated, including organic pollutants degradation, hydrogen production, and carbon dioxide reduction. Meanwhile, the mechanism and difficult level of these photocatalytic reactions are also described. Besides, metal organic frameworks (MOFs) as a novel type of photocatalysts have attracted growing attention. The novel combination of silver-based semiconductors with typical photoactive MOFs is highlighted based on the Z-scheme photocatalytic systems. Eventually, the future challenges and prospects in the development of silver-based semiconductor Z-scheme photocatalytic systems are presented.

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.

Ultrasound-Assisted Hydrothermal Fabrication of AgI/MFeO3/g-C3N4 (M = Y, Gd, La) Nano Sheet–Sphere–Sheet Photocatalysts with Enhanced Photodegradation Activities for Norfloxacin

AgI/MFeO3/g-C3N4 (M = Y, Gd, La) nano sheet–sphere–sheet photocatalysts were synthesized by a simple ultrasound-assisted hydrothermal approach. We characterized the microstructure, surface morphology, and optical absorption capacity of the obtained samples. According to the characterization results, AgI/MFeO3/g-C3N4 (M = Y, Gd, La) nano sheet–sphere–sheet photocatalysts were successfully obtained. MFeO3 nanospheres and AgI nanosheets were dispersed evenly on the surface of g-C3N4 nanosheets. AgI/MFeO3/g-C3N4 showed remarkable photocatalytic. Especially, 95% of NOF was photodegradated over AgI/LaFeO3/g-C3N4 within 3 h and the higher photocatalytic performance still remained after six cycles. Additionally, The N2 adsorption–desorption isotherms of AgI/MFeO3/g-C3N4 showed that AgI/LaFeO3/g-C3N4 possessed the highest specific surface area (79.32 m2/g). The result of scavenging experiment revealed that ·O2−, h+, and ·OH were the main roles in the photodegradation process. Benefitting from the nice energy band matching, MFeO3 acted as the center of photogenerated electrons migration and separation provided more direct electron channels. This work proposes an effective approach for the design and configuration of dual Z-scheme photocatalysts to accomplish the removal of organic contaminants based on g-C3N4.

Three-dimensional hierarchical porous carbon structure derived from pinecone as a potential catalyst support in catalytic remediation of antibiotics

In this study, pinecone was converted via two stage pyrolysis to produce low cost activated carbon. Furnace pyrolysis was used in the first step to convert pinecone to carbonized material, followed by microwave pyrolysis of the carbonized material activated with KOH to obtain activated carbon (ACK) materials as a suitable catalyst support. The ACK samples were characterized by their morphology, structural, adsorption and electrochemical properties. The optimized ACK 2.24-16 prepared from the pinecone had a complex three-dimensional (3D)-hierarchical porous structure, with an abundance of micropores and mesopores compared to other ACK samples judging from the high iodine number (1900 mg g^-1) and the methylene blue number (4000 mg g^-1) capacity. The optimized ACK 2.24-16 had the highest current response and least charge transfer resistance, along with moderate surface area (427 m² g^-1) as a promising photocatalyst support. The 3D hierarchical porous ACK significantly assisted catalyst dispersion, and enhanced visible light absorption and fast interfacial charge transfer. This work shows the promising aspect of utilizing pinecone to produce a low-cost photocatalyst support for environmental remediation.

Nitrogen deficient carbon nitride for efficient visible light driven tetracycline degradation: a combination of experimental and DFT studies

The narrow visible-light absorption range and a high recombination rate of photo-excited electrons and holes are the main reasons for the confined photocatalytic performance of graphitic carbon nitride (g-C₃N₄).

Z-scheme 2D-m-BiVO4 networks decorated by a g-CN nanosheet heterostructured photocatalyst with an excellent response to visible light

For economical water splitting and degradation of toxic organic dyes, the development of inexpensive, efficient, and stable photocatalysts capable of harvesting visible light is essential. In this study, we designed a model system by grafting graphitic carbon nitride (g-C₃N₄) (g-CN) nanosheets on the surface of 2D monoclinic bismuth vanadate (m-BiVO₄) nanoplates by a simple hydrothermal method. This as-synthesized photocatalyst has well-dispersed g-CN nanosheets on the surface of the nanoplates of m-BiVO₄, thus forming a heterojunction with a high specific surface area. The degradation rate for bromophenol blue (BPB) shown by BiVO₄/g-CN is 96% and that for methylene blue (MB) is 98% within 1 h and 25 min, respectively. The 2D BiVO₄/g-CN heterostructure system also shows outstanding durability and retains up to ∼95% degradation efficiency for the MB dye even after eight consecutive cycles; the degradation efficiency for BPB does not change too much after eight consecutive cycles as well. The enhanced photocatalytic activities of BiVO₄/g-CN are attributed to the larger surface area, larger number of surface active sites, fast charge transfer and improved separation of photogenerated charge carriers. We proposed a mechanism for the improved photocatalytic performance of the Z-scheme photocatalytic system. The present work gives a good example for the development of a novel Z-scheme heterojunction with good stability and high photocatalytic activity for toxic organic dye degradation and water splitting applications.

For economical water splitting and degradation of toxic organic dyes, the development of inexpensive, efficient, and stable photocatalysts capable of harvesting visible light is essential.

Enhanced photoelectric conversion efficiency: A novel h-BN based self-powered photoelectrochemical aptasensor for ultrasensitive detection of diazinon

This work presents a novel hexagonal boron nitride (h-BN) based self-powered photoelectrochemical (PEC) aptasensor for ultrasensitive detection of diazinon (DZN) with excellent photoelectric conversion efficiency. It was the first time that h-BN based materials were applied to PEC aptasensor, in which the construction of Z-scheme heterojunction of h-BN and graphitic carbon nitride (CN) via doping sulfur into h-BN was innovatively proposed. Meanwhile, Au nanoparticles (AuNPs) were utilized for the surface plasmon resonance (SPR) effect and the formation of new recombination centers. The charge transfer mechanism was expounded and verified by the electron spin resonance (ESR) spin-trap technique. The proposed PEC aptasensor for determination of DZN exhibited a wide linear range from 0.01 to 10000 nM and a low detection limit of 6.8 pM with superb selectivity and remarkable stability. Moreover, the constructed PEC aptasensor performed well with excellent recoveries in three different real samples. This work illustrated that PEC aptasensor is a promising alternative to conventional analytical technologies for the detection of DZN and other organophosphorus (OP) pesticides. The designing ideas of the proposed h-BN based material can provide a foothold for the innovative construction of photoactive materials for PEC bioanalysis.

Cobalt oxide loaded graphitic carbon nitride as adsorptive photocatalyst for tetracycline removal from aqueous solution

The treatment of antibiotic-containing wastewater is of great importance due to the potential threats of antibiotics to human and the ecosystem. We reported the preparation of cobalt oxide loaded graphitic carbon nitride (CoO/g-C₃N₄) by an impregnation-calcination method for tetracycline (TC) removal from aqueous solution. The developed CoO/g-C₃N₄ exhibited high adsorption capacity and fast adsorption kinetic for TC due to the complexation of TC with surface loaded CoO. In particular, 7%CoO/gC₃N₄3 sample presented a maximum TC adsorption capacity of 391.4 mg g^-1. It was found that Langmuir and pseudo-second order kinetic models fitted TC adsorption process well. Further photocatalytic studies showed that CoO loaded g-C₃N₄ was active for TC photodegradation, although the photocatalytic reaction rate constant was lower than that of native g-C₃N₄. CoO nanoparticles loading on g-C₃N₄ played the major role of adsorption sites rather than cocatalyst for photocatalysis. We believe that the developed CoO/g-C₃N₄ could be a potential adsorptive photocatalyst for antibiotic pollutants removal from wastewater.

One-pot construction of Cu and O co-doped porous g-C3N4 with enhanced photocatalytic performance towards the degradation of levofloxacin

Cu and O co-doped porous g-C₃N₄ with outstanding photocatalytic degradation of levofloxacin performance was synthesized by a one-pot thermal polymerization approach.

Bio-inspired Z-scheme g-C3N4/Ag2CrO4 for efficient visible-light photocatalytic hydrogen generation

Due to low charge separation efficiency and poor stability, it is usually difficult for single-component photocatalysts such as graphitic carbon nitride (g-C₃N₄) and silver chromate (Ag₂CrO₄) to fulfill photocatalytic hydrogen production efficiently. Z-scheme charge transport mechanism that mimics the photosynthesis in nature is an effective way to solve the above problems. Inspired by photosynthesis, we report Ag₂CrO₄ nanoparticles-decorated g-C₃N₄ nanosheet as an efficient photocatalyst for hydrogen evolution reaction (HER) with methanol as sacrificial agent. The formation of Z-scheme g-C₃N₄/Ag₂CrO₄ nanosheets photocatalysts could inhibit the recombination of photogenerated electron-hole pairs, promote the generation of hydrogen by photosplitting of water. The experiment results indicate that g-C₃N₄/Ag₂CrO₄ nanocomposites present enhanced photocatalytic activity and stability in the H₂ evolution of water splitting. And the nanocomposites g-C₃N₄/Ag₂CrO₄(23.1%) show the 14 times HER efficiency compared to that of bare g-C₃N₄.

Antibiotic removal from water: A highly efficient silver phosphate-based Z-scheme photocatalytic system under natural solar light

Photocatalytic degradation is an alternative method to remove pharmaceutical compounds from water, however it is hard to achieve efficient rate because of the low efficiency of photocatalysts. In this study, an efficient Z-Scheme photocatalyst was constructed by integrating graphitic carbon nitride (CN) and reduced graphene oxide (rGO) with AP via a simple facile precipitation method. Excitedly, ternary AP/rGO/CN composite showed superior photocatalytic and anti-photocorrosion performances under both intense sunlight and weak indoor light irradiation. NOF can be completely degraded in only 30 min and about 85% of NOF can be mineralized after 2 h irradiation under intensive sunlight irradiation. rGO could work not only as a sheltering layer to protect AP from photocorrosion but also as a mediator for Z-Scheme electron transport, which can protect AP from the photoreduction. This strategy could be a promising method to construct photocatalytic system with high efficiency for the removal of antibiotics under natural light irradiation.

In-situ preparation of silver salts/collagen fiber hybrid composites and their photocatalytic and antibacterial activities

To promote the utilization of collagen fiber, silver salts/collagen fiber hybrid composites with photocatalytic and antibacterial activities were successfully prepared in this study via the in-situ organic-inorganic process. The surface morphology, chemical composition and structure were discussed. Scanning electron microscopy (SEM) observation showed that the silver salts/collagen fiber hybrid composites were successfully prepared with silver salt particles (300-500 nm) distributing evenly on the surface of collagen fiber. X-ray diffraction (XRD) patterns and Fourier transform infrared spectroscopy (FTIR) analysis provided strong evidence for the successful coating of silver salts on the surface of collagen fiber and the hybrid mechanism was subsequently discussed. The photocatalytic activity was evaluated by degrading methyl orange (MO) under ultraviolet (UV) light and visible light, respectively. The results indicated that AgCl/Collagen Fiber showed the most efficient photocatalytic activity under UV and visible light irradiation. Furthermore, the introduction of Ag⁺ endowed the photocatalysts with antibacterial performance, which was investigated by measuring the width of the bacteriostatic belts. The results indicated the antibacterial activity of the composites, proving that the photocatalysts were durable and reusable.

Investigation of the visible light photocatalytic activity of BiVO4 prepared by sol gel method assisted by ultrasonication

Visible light induced photocatalyst BiVO₄ with monoclinic scheelite structure has been synthesised via sol gel method assisted by ultrasonication. The prepared samples were characterised using X-ray diffraction (XRD), scanning electron microscope (SEM), UV-Vis diffused reflectance spectroscopy (DRS) techniques. The photocatalytic efficiency was evaluated by decolourisation of MB under visible light irradiation. The effect of ultrasound output power on the properties of BiVO₄ during and after preparation by sol-gel method has been compared with normal agitated sample (As prepared). The power of ultrasonic vibration has been varied and an ideal output power which yields better catalytic efficiency is determined. BiVO₄ sonicated with 80 W during preparation 80 W (D) exhibited relatively high surface area, better surface morphology and better catalytic efficiency compared to other samples which were sonicated with 100, 160 and 200 W. The results signify that the photodegradation rate of BiVO₄ 80 W (D) sample is high up to 96% in 90 min compared to other samples. Change in morphology leading to better catalytic efficiency was obtained just by exposing the sample to ultrasonic radiation without addition of any surfactant. The recovery test showed that the sample was stable for four consecutive cycles. Using radical test, a reasonable mechanism for photodegradation has been proposed.