Nanoarchitectonics has gained recent attention from researchers and can be utilized in the development of catalytic systems with unique morphological features, high surface area and engineered catalytic sites. In this work, biomimetic substrates have been fabricated by replicating wings of a grasshopper insect with interesting surface hierarchical architecture by employing a soft lithography technique. Further, the substrates were engineered to form a hetero-nanojunction of gold and silver nanolayers by using the sputtering technique. The replicated substrates possess multi-wall supported sharp edged pods type morphology and provide a good degree of adhesion to the deposited metal layers with increased surface area in comparison to a flat control substrate. The catalytic potential of these metal-coated nanoarchitectonics-based substrates was examined as dip catalysts for degradation of a model organic pollutant, methylene blue in the presence of sodium borohydride as a reducing agent. The biomimetic substrate showed higher photocatalytic degradation of methylene blue due to the enhanced plasmonic effect in comparison to the flat control substrate. The mechanism of the degradation has been discussed in detail in the presence and absence of light irradiation. This work paves way for the design and development of recyclable and efficient dip catalysis substrates by combining the nanoarchitectonics and biomimetic approaches.

https://link.springer.com/content/pdf/10.1007/s10904-021-01902-9.pdf

Ultrathin Au–Ag Heterojunctions on Nanoarchitectonics Based Biomimetic Substrates for Dip Catalysis

A novel g-C3N4/BiOI/Ag2WO4 heterojunction for efficient degradation of organic pollutants under visible light irradiation

Recently, halides (silver halides, AgX; perosvkite halides, ABX 3 ) and oxyhalides (bismuth oxyhalides, BiOX) based nanomaterials are noticeable photocatalysts in the degradation of organic water pollutants . Therefore, we review the recent reports to explore improvement strategies adopted in AgX, ABX 3 and BiOX (X = Cl, Br and I)-based photocatalysts in water pollution remediation. Herein, the photocatalytic degradation performances of each type of these photocatalysts were discussed. Strategies such as tailoring the morphology, crystallographic facet exposure, surface area, band structure, and creation of surface defects to improve photocatalytic activities of pure halides and BiOCl photocatalysts are emphasized. Other strategies like metal ion and/or non-metal doping and construction of composites, adopted in these photocatalysts were also reviewed. Furthermore, the way of production of active radicals by these photocatalysts under ultraviolet/visible light source is highlighted. The deciding factors such as structure of pollutant, light sources and other parameters on the photocatalytic performances of these materials were also explored. Based on this literature survey, the need of further research on AgX, ABX 3 and BiOX-based photocatalysts were suggested. This review might be beneficial for researchers who are working in halides and oxyhalides-based photocatalysis for water treatment . • Photocatalysis gains significant attention in aquatic organic pollutant removal. • Silver and perovskite halides and bismuth oxyhalides are emerging as promising photocatalysts. • Improvement strategies in halide and oxyhalides-based photocatalysts were outlined. • Influencing factors for the photocatalytic degradation of organic pollutants were discussed. • The current challenges in this field have been explored. 

Halides and oxyhalides-based photocatalysts for abatement of organic water contaminants - An overview.

In this work, graphitic carbon nitride (g-C3N4) immobilized Bi2S3/Ag2WO4 (BS/AW/CN) heterojunction was successfully fabricated using a facile multi-step approach. The fabricated nanomaterials were characterized using different sophisticated technologies. The morphological investigations revealed the existence of g-C3N4 nanosheets loaded with Ag2WO4 and Bi2S3 in a nanorod-like structure. The BS/AW/CN nanocomposite exhibited improved surface area, which was attributed to the regular deposition of Bi2S3/Ag2WO4 on the surface of g-C3N4 nanosheets. The obtained BS/AW/CN heterojunction displayed excellent light absorption ability with promoted photoelectrochemical properties, which was attributed to the lower band gap energy of Bi2S3 species. The BS/AW/CN (0.25 g/L) showed superior photocatalytic antimicrobial activity against Staphylococcus aureus cells (∼1 × 107 CFU/mL) under 140 W of visible-light illumination, where complete inactivation activity was observed in 90 min. The disinfection kinetics verified the faster photoreaction process over BS/AW/CN compared with single and binary catalysts. The inactivated bacterial cells were further elucidated by fluorescence spectroscopy and electron microscopy techniques. The photocatalytic disinfection activity was also investigated under different operating conditions like pH, catalyst loading, and bacterial density. The stability studies verified the high photostability of the obtained heterojunction in five photoreaction runs, suggesting its potential applicability in wastewater disinfection systems. The electronic characteristics and radical trapping results were considered in justifying the dual-S-scheme heterojunction mechanism in the presence of BS/AW/CN. In conclusion, this work demonstrates the feasibility of an efficient visible-light responsive photocatalyst for Staphylococcus aureus cells disinfection in wastewater treatment systems. 

Fabrication of g-C3N4 nanosheets immobilized Bi2S3/Ag2WO4 nanorods for photocatalytic disinfection of Staphylococcus aureus cells in wastewater: dual S-scheme charge separation pathway

Radical polymerization of methyl methacrylate in an aqueous emulsion was carried out using the complex oxide RbTe15W05O6 as a photoinitiator under visible light irradiation with λ = 400–700 nm Study of the polymerization process and reaction products using methods of physical and chemical analysis (GPC, IR, NMR, etc) has shown that there are several directions of monomer transformations at the same time Polymethyl methacrylate with Mn ~ 140–145 kDa, produced in the organic phase, is a result of polymerization initiation by a hydroxyl radical formed due to complex transformations of electron–hole pairs during photocatalyst irradiation Moreover, the interaction of the hydroxyl radical with OH-groups on the complex oxide RbTe15W05O6 surface and the subsequent formation of oxygen-centered radicals lead to grafting polymer macromolecules on the photocatalyst surface In addition, methyl methacrylate is able to oxidize to a cyclic dimer with terminal double bonds and form a polymer with cyclic dimer links due to coordination by double bonds on the RbTe15W05O6 surface The high activity of the hydroxyl radical allows to obtain the graft copolymer PMMA-pectin by grafting the polymer product on the surface of the natural polymer-pectin Comparison of the sponge morphology of the graft copolymer PMMA-pectin and the initial pectin samples using the scanning electron microscopy has shown a noticeable difference in their structural and topological organization It is especially interesting in terms of studying the properties of the graft copolymer as a material for the scaffolds

/pdf/features-of-polymerization-of-methyl-methacrylate-using-a-13avrgjda2.pdf

Features of Polymerization of Methyl Methacrylate using a Photocatalyst—the Complex Oxide RbTe1.5W0.5O6

Ag2WO4 is a typically noble metal based photocatalyst with highly efficient photocatalytic activity. However, due to photocorrosion, the pristine Ag2WO4 is prone to inactivation during illumination. Constructing composite photocatalyst may be a useful method to promote the stability of Ag2WO4. In this work, Ag2WO4/graphitic carbon nitride nanotubes (g-C3N4 NTs) composite photocatalyst was prepared by adopting an in-situ composite strategy. The photocatalytic performance of the samples was discussed by the degradation of rhodamine B under visible light, and the catalytic mechanism was also analyzed. The characterization results show that the photocatalytic efficiency of the as-prepared Ag2WO4/g-C3N4 NTs composite increases firstly and then decreases along with the increase of the Ag2WO4 content. When the theoretical molar ratio of Ag2WO4:g-C3N4 NTs reaches 3:2, the photocatalytic degradation efficiency achieves the optimal value, that is 92.4% within 20 min, which obviously exceeds 2.8% of pure Ag2WO4 and 48.9% of pure g-C3N4 NTs. Moreover, the separation and migration efficiency of photoelectron–hole pairs of the composites can be accelerated in comparison with pure samples. In addition, superoxide radicals and hydroxyl radicals play major roles in the photocatalytic degradation process.

Study on Ag 2 WO 4 /g-C 3 N 4 Nanotubes as an Efficient Photocatalyst for Degradation of Rhodamine B

The SnO2 quantum dots (SnO2QDs)/ZnS nanosheets (ZnSNs) heterojunction was fabricated via an in-situ synthetic method at room temperature. Rhodamine B, potassium dichromate, and tetracycline were used to discuss the photocatalytic activities of the as-prepared samples under the visible light illumination. The photocatalytic mechanism of the as-prepared samples was also proposed. The experimental results indicate that the degradation efficiency of the as-prepared SnO2QDs/ZnSNs heterojunction first increases and then decreases with increasing the usage of ZnSNs. When the mass ratio of SnO2QDs to ZnSNs is 1: 2 in 180 min, the asprepared samples have the highest degradation efficiency of 89.1% for rhodamine B, 97.7% for potassium dichromate, and 83.8% for tetracycline, which are much higher than 51.7%, 26.8%, and 0.9% of pure SnO2QDs as well as 37.9%, 87.1%, and 19.1% of pure ZnSNs, respectively. After it is repeatedly degraded for 3 times, it possesses the degradation efficiency of 62.5% for rhodamine B, which increases by 200.5% in comparison with 20.8% of the pure SnO2QDs. Moreover, the enhanced photocatalytic performances of the as-prepared hybrids are attributed to the formation of heterojunction between the SnO2QDs and ZnSNs. In addition, hydroxyl radicals and superoxide anion radicals play major roles during the photocatalytic degradation process, while holes play a minor role.

In-situ Synthesis of SnO 2 Quantum Dots/ZnS Nanosheets Heterojunction as a Visible-light-driven Photocatalyst for Degradation of Rhodamine B, Potassium Dichromate and Tetracycline

The SrCO3/AgI photocatalysts were prepared via a co-precipitation method by using SrCO3 as a co-photocatalyst and AgI as a photo sensitizer. X-ray diffraction, field emission scanning electron microscope, X-ray photoelectron spectrometer, UV-vis diffuse reflectance spectroscopy and electrochemical impedance spectroscope were used to analyze the structure, micro-morphology, chemical compositions, optical properties and photo-generated carrier behaviors of the as-prepared samples, respectively. The photocatalytic degradation mechanism of the as-developed composites was also proposed. Analysis results show SrCO3, an insulator, can improve the photocatalytic performances and recyclability of AgI for degrading tetracycline under visible light. As the theoretical molar ratio of Sr(NO3)2 to AgNO3 increases, the degradation efficiency of the hybrids first increases and then descends. When the theoretical molar ratio of that is 1: 1, it acquires the maximum of 66.6% within 8 min. This is higher than 32.0% of pure AgI and 34.0% of SrCO3. Moreover, after three times degradations it is 63.0%, which is higher than 13.6% of AgI. The improvement of the photocatalytic performance of the sample is attributed to the construction of hybrids. The main activated species in catalysis process are superoxide radicals.

Xutao Liu

Papers

Study on Ag 2 WO 4 /g-C 3 N 4 Nanotubes as an Efficient Photocatalyst for Degradation of Rhodamine B

In-situ Synthesis of SnO 2 Quantum Dots/ZnS Nanosheets Heterojunction as a Visible-light-driven Photocatalyst for Degradation of Rhodamine B, Potassium Dichromate and Tetracycline

Visible-Light-Sensitive SrCO3/AgI Hybrids for Tetracycline Degradation