Surface photosensitization of ZnO by ZnS to enhance the photodegradation efficiency for organic pollutants

It is challenging to develop a material which has low cost, high activity, good stability and recyclability under light exposure. Apart from these properties, the photocatalyst should also have good visible region absorbance and low electron-hole pair recombination rate. Keeping all this in view, we have designed a simple scalable synthesis of ZnO–ZnS heterostructures for the photocatalytic treatment of industrial waste (p-nitrophenol and methyl orange). The ZnO–ZnS heterostructures are synthesized via a solvent-free route by thermal annealing of solid-state mixture of ZnO and thiourea (a sulphur source) which results in ZnO–ZnS core shell kind of heterostructure formation. The interface formation between the ZnO–ZnS heterostructure favored the band-gap reduction in comparison to the bare ZnO and ZnS nanoparticles. Further, these ZnO–ZnS heterostructures were utilized as a photocatalyst for the degradation of toxic phenolic molecules (p-nitrophenol) and harmful organic dyes (methyl orange) present in the water under the light exposure (> 390 nm).

Transition metal sulfides meet electrospinning: versatile synthesis, distinct properties and prospective applications

One-dimensional (1D) electrospun nanomaterials have attracted significant attention due to their unique structures and outstanding chemical and physical properties such as large specific surface area, distinct electronic and mass transport, and mechanical flexibility. Over the past years, the integration of metal sulfides with electrospun nanomaterials has emerged as an exciting research topic owing to the synergistic effects between the two components, leading to novel and interesting properties in energy, optics and catalysis research fields for example. In this review, we focus on the recent development of the preparation of electrospun nanomaterials integrated with functional metal sulfides with distinct nanostructures. These functional materials have been prepared via two efficient strategies, namely direct electrospinning and post-synthesis modification of electrospun nanomaterials. In this review, we systematically present the chemical and physical properties of the electrospun nanomaterials integrated with metal sulfides and their application in electronic and optoelectronic devices, sensing, catalysis, energy conversion and storage, thermal shielding, adsorption and separation, and biomedical technology. Additionally, challenges and further research opportunities in the preparation and application of these novel functional materials are also discussed.

Durable Light-Driven Three-Dimensional Smart Switchable Superwetting Nanotextile as a Green Scaled-Up Oil-Water Separation Technology

Stimuli-responsive polymer architectures are attracting a lot of interest, but it still remains a great challenge to develop effective industrial-scale strategies. A single-stage and cost-effective approach was applied to fabricate a three-dimensional (3D) smart responsive surface with fast and reversibly switchable wetting between superhydrophobicity and superhydrophilicity/underwater superoleophobicity properties induced by photo and heat stimuli. Commercially available PVDF and P25TiO₂ as starting materials fabricated with a scaled-up electrospinning approach were applied to prepare 3D smart switchable PVDF-P25TiO₂ nanotextile superwetted by both UV and solar light that is simply recovered by heat at a reasonable time. The superhydrophilic/underwater superoleophobic photo-induced nanotextile will act in "water-removing" mode in which water quickly passes through and the oil is blocked on the surface. An acceptable recycling, reusing, and superior antifouling and self-cleaning performance arising from a TiO₂ photocatalytic effect makes it highly desired in a green scaled-up industry oily wastewater treatment technology. With these advantages, a large-scale industrial production process can be simply simulated by applying a conducting mesh-like collector substrate.

Photocatalytic Active Mesoporous Carbon/ZnO Hybrid Materials from Block Copolymer Tethered ZnO Nanocrystals

Severe water pollution issues present an important contemporary challenge that drives the development and advancement of efficient and environmentally benign photocatalysts that enable the degradation of pollutants upon visible light irradiation. One example is zinc oxide/carbon (ZnO/C) hybrid materials that have been shown to be effective photocatalysts. To maximize the effectiveness of ZnO/C hybrids, materials with high accessible surface area of ZnO are required. Here, a novel strategy is presented to enable the synthesis of fine dispersions of ZnO nanoparticles within a porous carbon matrix. The synthesis entails the grafting of ZnO nanparticles with polystyrene-b-poly(styrene-co-acrylonitrile) (PS-b-PSAN) block copolymer and subsequent pyrolysis of the material under inert gas (N₂) atmosphere. During the pyrolysis process, the PS block effectively prevents agglomeration of ZnO particles, thus resulting in a fine dispersion of ZnO nanocrystals within a prorous C matrix. Materials are found to exhibit a dye adsorption capacity of 125 mg g^-1 (from a methylene blue aqueous solution with a concentration of 305 mg L^-1) and dye degradation rate constant of 0.021 min^-1. The significant increase of effective surface area and degradation efficacy (as compared to ZnO/C synthesized by the pyrolysis of binary PSAN/ZnO blends) is rationalized as a consequence of the increased porosity that promotes dye adsorption and transport within the hybrid material.

Structure-Property Relationships of Nanosheeted 3D Hierarchical Roughness MgAl-Layered Double Hydroxide Branched to an Electrospun Porous Nanomembrane: A Superior Oil-Removing Nanofabric

A straightforward approach was successfully developed to fabricate a well-designed three-dimensional rough sheetlike MgAl-layered double hydroxide (LDH) array to stand vertically on poly(acrylonitrile) porous nanofibrous membranes based on an electrospun-nanofiber-templated in situ hydrothermal strategy, and then the surface was modified with cyclohexanecarboxylic acid. The as-spun highly dense ordered sheetlike LDH porous nanofabric exhibited a superior durability in superhydrophobicity and superoleophilicity, which has achieved high oil-removing capability including both oil harvesting and oil separation to harvest/separate a wide range of organic solvents and oils from an oil-water mixture and, especially, exhibited a very good recycling and reusing performance. Interestingly, a steady water repellency was obtained against both drinkable hot (about 95 °C) and cool water. Outstanding oil harvesting, oil separation, and highly durable water repellant can be attributed to an effective synergistic effect between the high-density roughness of LDH nanosheets modified with acid and the very high porosity in the electrospun nanofibers, as well as the interspace between LDH nanosheets that acted as both a textile for selective oil separation and a container for penetrated oil storage, leading to special wettability, making the as-spun nanofabric a promising textile for large-scale removal and recollection of hydrophobic spillage on the water surface.

ZnO long fibers: large scale fabrication, precursor and the transformation process, microstructure and catalytic performance

Fibrous ZnO catalysts were fabricated for easy recycling and better application in a continuous mode in catalytic reactions.