Topotactic synthesis of mesoporous ZnS and ZnO nanoplates and their photocatalytic activity

Ethylenediamine-assisted solvothermal synthesis of ZnS/ZnO photocatalytic heterojunction for high-efficiency hydrogen production

Organic-inorganic hybrid materials have emerged as a class of novel materials over the last two decades, as they combine functional organic components and inorganic building blocks into unique materials through various chemical or physical interactions. In the present work, the importance of the use of ethylenediamine in sulfided materials applied to photocatalytic processes in the H2 production is demonstrated. The ZnS/ZnO heterojunction was prepared by the solvothermal synthesis in the presence and absence of ethylenediamine. The photocatalytic behavior showed that the addition of ethylenediamine increases the photocatalytic efficiency up to eight times compared to the photocatalyst without the organic agent. The materials were characterized by X-ray diffraction, scanning electron microscopy, infrared and UV-visible spectroscopies of solids, N2 adsorption-desorption isotherms, X-ray photoelectron spectroscopy, and photoelectrochemical characterization. The ethylenediamine plays a double role: to stabilize the cubic phase of zinc sulfide and to act as a promoter molecule of charge transfer on the surface of ZnS/ZnO/en heterojunction, slowing down the rate of recombination of the electron-hole pair, which is reflected in a decrease in the resistance to transfer of charge carriers, improving the H2 production rate until 1564 µmol h-1 g-1.

Optimizing Antimicrobial Efficacy: Investigating the Impact of Zinc Oxide Nanoparticle Shape and Size

Zinc oxide nanoparticles (ZnO NPs) have been investigated due to their distinct properties, variety of structures and sizes, and mainly for their antimicrobial activity. They have received a positive safety evaluation from the European Food Safety Authority (EFSA) for packaging applications as transparent ultraviolet (UV) light absorbers based on the absence of significant migration of zinc oxide in particulate form. ZnO NPs with different morphologies (spherical, flower, and sheet) have been synthesized via different sol-gel methods and extensively characterized by several solid-state techniques, namely vibrational spectroscopy, powder X-ray diffraction (XRD), scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS), Fourier Transform Infrared Spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-VIS), electron paramagnetic resonance (EPR), and nitrogen adsorption-desorption isotherms. The ZnO NPs were assessed for their antibacterial activity against Escherichia coli (gram-negative bacteria) and Staphylococcus aureus (gram-positive bacteria) to study the influence of morphology and size on efficacy. ZnO NPs with different morphologies and sizes demonstrated antimicrobial activity against both bacteria. The highest microbial cell reduction rate (7-8 log CFU mL-1 for E. coli and 6-7 log CFU mL-1 for S. aureus) was obtained for the sheet- and spherical-shaped NPs as a result of the high specific surface area. In fact, the higher surface areas of the sheet- and spherical-shaped nanoparticles (18.5 and 13.4 m2 g-1, respectively), compared to the flower-shaped NPs (5.3 m2g-1), seem to promote more efficient bacterial cell reduction. The spherical-shaped particles were also smaller (31 nm) compared with the flower-shaped (233 × 249 nm) ones. The flower ZnO NP resulted in a 4-5 log CFU mL-1 reduction for E. coli and 3-4 log CFU mL-1 reduction for S. aureus. The lower apparent antibacterial activity of the flower-shaped could be associated with either the lack of defects on the particle core or the shape shielding effect. Compared to S. aureus, E. coli seems to be less resistant to ZnO NPs, which may be explained by the characteristics of its cell membrane. With simple synthesis techniques, which do not allow the size and shape of the nanoparticles to be controlled simultaneously, it is a challenge to elucidate the effect of each of these two parameters on antibacterial performance.

In situ fabrication of Ag decorated porous ZnO photocatalyst via inorganic-organic hybrid transformation for degradation of organic pollutant and bacterial inactivation

In this study, in situ silver (Ag) - porous ZnO photocatalysts were synthesized via solvothermal and post-annealing treatment. The formation of the porous ZnO structure due to the removal of organic moieties from the inorganic-organic hybrids Ag-ZnS(en)0.5 during the annealing process. The optimal Ag-ZnO photocatalyst showed excellent photocatalytic degradation activity, with 95.5% orange II dye and 97.2% bisphenol A (BPA) degradation under visible light conditions. Additionally, the photocatalytic inactivation of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) led to a 97% inactivation rate after 2 h under dark conditions. Trapping experiments suggest that the superoxide anion (O2-) radicals are the main active species to degrade the organic dye. The improved photocatalytic dye degradation activity and inactivation of bacteria were attributed to the synergistic effect of Ag and porous ZnO structure, increased surface area, and efficiently separated the photoexcited charge carriers. This work could provide an effective strategy for the synthesis of porous structures toward organic pollutant degradation and bacterial inactivation in wastewater.

Sulfidogenic Bioreactor-Mediated Formation of ZnS Nanoparticles with Antimicrobial and Photocatalytic Activity

The use of sulfidogenic bioreactors is a biotechnology trend to recover valuable metals such as copper and zinc as sulfide biominerals from mine-impacted waters. In the present work, ZnS nanoparticles were produced using "green" H₂S gas generated by a sulfidogenic bioreactor. ZnS nanoparticles were physico-chemically characterized by UV-vis and fluorescence spectroscopy, TEM, XRD and XPS. The experimental results showed spherical-like shape nanoparticles with principal zinc-blende crystalline structure, a semiconductor character with an optical band gap around 3.73 eV, and fluorescence emission in the UV-visible range. In addition, the photocatalytic activity on the degradation of organic dyes in water, as well as bactericidal properties against several bacterial strains, were studied. ZnS nanoparticles were able to degrade methylene blue and rhodamine in water under UV radiation, and also showed high antibacterial activity against different bacterial strains including Escherichia coli and Staphylococcus aureus. The results open the way to obtain valorous ZnS nanoparticles from the use of dissimilatory reduction of sulfate using a sulfidogenic bioreactor.

One-step preparation of MoOx/ZnS/ZnO composite and its excellent performance in piezocatalytic degradation of Rhodamine B under ultrasonic vibration

This paper synthesized a new type of ternary piezoelectric catalyst MoO_x/ZnS/ZnO (MZZ) by a one-step method. The catalytic degradation of Rhodamine B (RhB) solution (10 µg/g, pH = 7.0) shows that the composite catalyst has excellent piezoelectric catalytic activity under ultrasonic vibration (40 kHz). The piezoelectric degradation rate of the optimal sample reached 0.054 min^-1, which was about 2.5 times that of pure ZnO. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS) technologies were used to analyze the structure, morphology, and interface charge transfer properties of the MZZ piezocatalysts. The results showed that the composite catalyst may have a core-shell structure. ZnS is coated on the surface of ZnO, while MoO_x adheres to the surface of ZnS. This structure endowed MZZ larger specific surface area than ZnO, which benefits the RhB adsorption. More importantly, the formed heterojunction structure between ZnS and ZnO promotes the separation of positive and negative charges induced by the piezoelectric effect. MoO_x species may act as a charge trap to further promote more carriers to participate in the reaction. In addition, MoO_x may also be beneficial in adsorbing dyes. Active species capture experiments show that superoxide radicals and holes are the main active species in piezoelectric catalytic reactions on MZZ catalysts.

Collaborative hydrothermal and calcination fabrication of ZnOS heterostructures for visible-light-driven H2 production

Photocatalytic water splitting is forecasted as a promising strategy for H₂ production. In this work, novel zinc oxide/zinc sulfide (ZnOS-x) (x = 1, 2, 3 and 4) heterostructures were fabricated by a collaborative hydrothermal and calcination method with different amounts of trithiocyanuric acid. The formation of ZnOS-x heterostructures was confirmed by PXRD, XPS, and HRTEM. Moreover, ZnOS-3 nanoparticles exhibited homogeneous and smooth surface morphology structure. ZnOS-3 displayed efficient charge separation and transfer efficiency upon photoinduction. ZnOS-3 showed the highest average H₂ evolution reaction rate (78.87 μmol h^-1) under visible-light irradiation, which increased with increase in the ratio of trithiocyanuric acid in the ZnOS-x series. This work provides a new insight to prepare uniformly integrated heterostructures of metal oxides/sulfides for visible-light-driven H₂ generation.

Two-dimensional ZnS@N-doped carbon nanoplates for complete lithium ion batteries

Metal sulfides are promising anode materials for lithium ion batteries because of the high specific capacities and better electrochemical kinetics comparing to their oxide counterparts. In this paper, novel monocrystalline wurtzite ZnS@N-doped carbon (ZnS@N-C) nanoplates, whose morphology and phase are different from the common ZnS particles with cubic phase, are successfully synthesized. The ZnS@N-C nanoplates exhibit long cycle life with a high reversible specific capacity of 536.8 mAh · g^-1after 500 cycles at a current density of 500 mA · g^-1, which is superior to the pure ZnS nanoplates, illustrating the obvious effect of the N-doped carbon coating for mitigating volume change of the ZnS nanoplates and enhancing the electronic conductivity during charge/discharge processes. Furthermore, it is revealed that the ZnS single crystals with wurtzite phase in the ZnS@N-C nanoplates are transformed to the polycrystalline cubic phase ZnS after charge/discharge processes. In particular, the ZnS@N-C nanoplates are combined with the commercial LiNi_0.6Co_0.2Mn_0.2O₂cathode to fabricate a new type of LiNi_0.6Co_0.2Mn_0.2O₂/ZnS@N-C complete battery, which exhibits good cycling durability up to 120 cycles at a charge/discharge rate of 1 C after the prelithiation treatment on the ZnS@N-C anode, highlighting the potential of the ZnS@N-C nanoplates anode material applied in lithium ion battery.

Preparation of ZnS@N-doped-carbon composites via a ZnS-amine precursor vacuum pyrolysis route

ZnS/carbon nanocomposites have potential electrochemical applications due to their improved conductivity and more active sites through modification of the carbon materials. Herein, we report a facile method to synthesize the nanocomposites comprising ZnS nanoparticles and nitrogen-doped carbon (ZnS@NC). The inorganic–organic hybrid ZnS-amine material ZnS(ba) (ba = n-butylamine) is synthesized on a large scale by a reflux method, which effectively shortens the reaction time while maintaining the high yield compared with the solvothermal method. Then ZnS(ba) is used as precursor for obtaining ZnS@NC nanocomposites via a vacuum pyrolysis route, in which the content of carbon and nitrogen can be controlled by adjusting the pyrolysis temperature. Further, a series of ZnS-amine hybrid materials ZnS(ha), ZnS(en)_0.5 and ZnS(pda)_0.5 (ha = n-hexylamine; en = ethylenediamine; pda = 1,3-propanediamine) are synthesized and used as precursors for the preparation of ZnS@NC materials, indicating the universality of this method. Moreover, the as-synthesized ZnS@NC materials exhibit remarkable lithium storage performance with outstanding cycling stability, high-rate capability and remarkable pseudo-capacitance characteristics.

ZnS/N-doped-carbon nanocomposites exhibiting remarkable Li storage performance are facilely prepared through the temperature-controllable vacuum pyrolysis of various ZnS-amine precursors.

Efficient removal of Congo red using curcumin conjugated zinc oxide nanoparticles as new adsorbent complex

Congo red is one of the common organic dyes that is found in water as waste of the industrial work. The use of congo red has long been of great concern, primarily because of its carcinogenic properties. Congo red can be isolated and removed from water by adsorption using nanoparticles. The use of zinc curcumin oxide, also known as curcumin conjugated zinc oxide, nanoparticles was elaborated for the first time in this work for this purpose. The optimization of the synthesis reaction of zinc curcumin oxide nanoparticles was established by modifying the flow rate of KOH, pH of the medium, different temperature, and in the presence or absence of chitosan polymer. These nanoparticles were characterized through SEM, UV-Visible absorption Spectroscopy, fluorescence spectroscopy, TGA, and XRD. It is found that during synthesis, addition of KOH dropwise in alkaline media improved the stability of the formed nanoparticles. Similarly, addition of chitosan has further increased their stability with only 10% mass loss. The importance of the formed nanoparticles was investigated by analyzing their efficiency in the adsorption of congo red where Zn(Cur)O had an adsorption capacity equal to 89.85 mg/g, which is one of the highest reported in literature, following the pseudo second order model. Nevertheless, negative surface charge of congo red and positive surface charge of Zn(Cur)O may also get supported by π-π interaction between curcumin and congo red that encourages adsorption in zinc curcumin oxide which is obstructed in the presence of chitosan.

Controllable sulphur vacancies confined in nanoporous ZnS nanoplates for visible-light photocatalytic hydrogen evolution

Controllable sulphur vacancies (S_v) confined in nanoporous ZnS nanoplates (S_v-ZnS) were prepared successfully via rapid heat treatment of ZnS(en)_0.5 nanoplates. S_v with controllable concentrations originating from the in situ doping of N atoms endowed S_v-ZnS with a visible-light photocatalytic H₂ production activity, having a positive linear correlation with S_v concentration.

Inorganic nanomaterials for fighting surface and airborne pathogens and viruses

Nowadays, the deadly viruses (including the latest coronavirus) and pathogens transmission became the major concern worldwide. Efforts have been made to combat with these fatal germs transmitted by the airborne, human-to-human contacts and contaminated surfaces. Thus, the antibacterial and antiviral materials have been widely researched. Meanwhile, the development of diverse nanomaterials with the antiviral traits provided several benefits to counter the threats from the surface and airborne viruses especially during the Covid-19 pandemic. Based on these facts, this paper overviewed the advantages of various nanomaterials that can disinfect and deactivate different lethal viruses transmitted through the air and surfaces. The past development, recent progress, future trends, environmental impacts, biocidal effects and prospects of these nanomaterials for the antiviral coating applications have been emphasized.

Polar mesoporous zinc sulfide nanosheets encapsulated in reduced graphene oxide three-dimensional foams for sulfur host

Lithium-sulfur (Li-S) batteries exhibit the high specific capacity and energy density, but prevented by the low coulombic efficiency and weak cycle life. Herein, we fabricate reduced graphene oxide (r-GO) three-dimensional (3D) foams encapsulating polar mesoporous zinc sulfide (ZnS) nanosheets and subsequently utilize the ZnS/r-GO foams to load sulfur (ZnS/r-GO/S) as cathodes for improving the performance of Li-S batteries. The mesoporous diameter of the ZnS nanosheets is approximately 10~30 nm and lots of pores in the 3D foams are observed. The porous structure provides abundant sites to adsorb and accommodate sulfur species. The cathode of the ZnS/r-GO/S exhibits 1259 mA h g^-1 of initial capacity and 971.9 mA h g^-1 of the reversible capacity after 200 cycles at 0.1 C (1 C = 1675 mA g^-1). At 1 C, it still exhibits the tiny capacity decay rate of 0.019% per cycle after 300 cycles. This work may be adopted to combine the nonpolar and polar materials as a 3D network structure for high-performance Li-S batteries.

Curcumin loaded zinc oxide nanoparticles for activity-enhanced antibacterial and anticancer applications

Zinc oxide nanoparticles and curcumin have been shown to be excellent antimicrobial agents and promising anticancer agents, both on their own as well as in combination. Together, they have potential as alternatives/supplements to antibiotics and traditional anticancer drugs. In this study, different morphologies of zinc oxide-grafted curcumin nanocomposites (ZNP–Cs) were synthesized and characterized using SEM, TGA, FTIR, XRD and UV-vis spectrophotometry. Antimicrobial assays were conducted against both Gram negative and Gram-positive bacterial stains. Spherical ZnO–curcumin nanoparticles (SZNP–Cs) and rod-shaped ZnO–curcumin nanoparticles showed the most promising activity against tested bacterial strains. The inhibition zones for these curcumin-loaded ZnO nanocomposites were consistently larger than their bare counterparts or pure curcumin, revealing an additve effect between the ZnO and curcumin components. The potential anticancer activity of the synthesized nanocomposites was studied on the rhabdomyosarcoma RD cell line via MTT assay, while their cytotoxic effects were tested against human embryonic kidney cells using the resazurin assay. SZNP–Cs exhibited the best balance between the two, showing the lowest toxicity against healthy cells and good anticancer activity. The results of this investigation demonstrate that the nanomatrix synthesized can act as an effective, additively-enhanced combination delivery/therapeutic agent, holding promise for anticancer therapy and other biomedical applications.

Curcumin-loaded ZnO nanocomposites act as an effective, synergistically-enhanced combination delivery/therapeutic agent, holding promise for anticancer and antimicrobial therapy with reduced toxicities.

Mixed phase nano-CdS supported on activated biomass carbon as efficient visible light-driven photocatalysts

Semiconductors are promising photocatalysts for the use of sunlight in energy conversion and environmental remediation. To this end, various synthetic pathways have been proposed to increase their photocatalytic efficiency, catalytic stability, recycle, and reuse. In this work, mixed phase CdS nanoparticles were loaded on the surface of activated biomass carbons to prepare composite photocatalysts via hydrothermal syntheses, which were further applied to photocatalytic degradation of rhodamine B (RhB) under visible irradiation. The composite photocatalysts displayed considerable specific surface area (up to 672 m² g^-1) and suitable band gap energy of ca. 2.1 eV. Due to the excellent light adsorption ability and chemical stability, these composite photocatalysts exhibited excellent photocatalytic capacity toward RhB degradation under visible irradiation. Moreover, the photocatalytic stability was also demonstrated by cyclic experiments, by which the composite photocatalysts retained over 80% of the initial catalytic activity after 4 consecutive runs.

Particulate Photocatalysts for Light-Driven Water Splitting: Mechanisms, Challenges, and Design Strategies

Solar-driven water splitting provides a leading approach to store the abundant yet intermittent solar energy and produce hydrogen as a clean and sustainable energy carrier. A straightforward route to light-driven water splitting is to apply self-supported particulate photocatalysts, which is expected to allow solar hydrogen to be competitive with fossil-fuel-derived hydrogen on a levelized cost basis. More importantly, the powder-based systems can lend themselves to making functional panels on a large scale while retaining the intrinsic activity of the photocatalyst. However, all attempts to generate hydrogen via powder-based solar water-splitting systems to date have unfortunately fallen short of the efficiency values required for practical applications. Photocatalysis on photocatalyst particles involves three sequential steps: (i) absorption of photons with higher energies than the bandgap of the photocatalysts, leading to the excitation of electron-hole pairs in the particles, (ii) charge separation and migration of these photoexcited carriers, and (iii) surface chemical reactions based on these carriers. In this review, we focus on the challenges of each step and summarize material design strategies to overcome the obstacles and limitations. This review illustrates that it is possible to employ the fundamental principles underlying photosynthesis and the tools of chemical and materials science to design and prepare photocatalysts for overall water splitting.

Controlled growth of ZnS/ZnO heterojunctions on porous biomass carbons via one-step carbothermal reduction enables visible-light-driven photocatalytic H2 production

Controlled growth of ZnS/ZnO heterojunctions on porous biomass carbons has been achieved via a one-step carbothermal reduction strategy.

Thermal Evolution of ZnS Nanostructures: Effect of Oxidation Phenomena on Structural Features and Photocatalytical Performances

ZnS nanosystems are being extensively studied for their possible use in a wide range of technological applications. Recently, the gradual oxidation of ZnS to ZnO was exploited to tune their structural, electronic, and functional properties. However, the inherent complexity and size dependence of the ZnS oxidation phenomena resulted in a very fragmented description of the process. In this work, different-sized nanosystems were obtained through two different low temperature wet chemistry routes, namely, hydrothermal and inverse miniemulsion approaches. These protocols were used to obtain ZnS samples consisting of 21 and 7 nm crystallites, respectively, to be used as reference material. The obtained samples were then calcinated at different temperatures, ranging from 400 to 800 °C toward the complete oxidation of ZnO, passing through the coexistence of the two phases (ZnS/ZnO). A thorough comparison of the effects of thermal handling on ZnS structural, chemical, and functional evolution was carried out by TEM, XRD, XAS, XPS, Raman, FT-IR, and UV-Vis. Finally, the photocatalytic activity in the H₂ evolution reaction was also compared for selected ZnS and ZnS/ZnO samples. A correlation between size and the oxidation process was observed, as the smaller nanosystems showed the formation of ZnO at lower temperature, or in a larger amount in the case of the ZnS and ZnO co-presence. A difference in the underlying mechanism of the reaction was also evidenced. Despite the ZnS/ZnO mixed samples being characterized by an increased light absorption in the visible range, their photocatalytic activity was found to be much lower.

Anti-Candidal Activity and In Vitro Cytotoxicity Assessment of Graphene Nanoplatelets Decorated with Zinc Oxide Nanorods

Candida albicans is the most common pathogenic fungus that is isolated in nosocomial infections in medically and immune-compromised patients. The ability of C. albicans to convert its form from yeast to hyphal morphology contributes to biofilm development that effectively shelters Candida against the action of antifungals molecules. In the last years, nanocomposites are the most promising solutions against drug-resistant microorganisms. The aim of this study was to investigate the antifungal activity of graphene nanoplateles decorated with zinc oxide nanorods (ZNGs) against the human pathogen Candida albicans. We observed that ZNGs were able to induce a significant mortality in fungal cells, as well as to affect the main virulence factors of this fungus or rather the hyphal development and biofilm formation. Reactive Oxygen Species (ROS) formation in yeast cells resulted one of the mechanisms of ZNGs to induce mortality. Finally, the toxicity of this nanomaterial was tested also on human keratinocyte cell line HaCaT. Our data indicated that ZNGs resulted not toxic when their aggregation state decreased by adding glycerol as emulsifier to ZNGs suspensions or when HaCaT cells were grown on ZNGs-coated glasses. Overall, the results that were obtained indicated that ZNGs could be exploited as an antifungal nanomaterial with a high degree of biocompatibility on human cells.

Facile fabrication of porous ZnS nanostructures with a controlled amount of S vacancies for enhanced photocatalytic performances

ZnS nanostructures of barbell-shaped porous and hollow nanoplates with a controlled amount of S vacancies have been facilely fabricated via the hydrothermal treatment of ZnS(en)_0.5 (en = ethylenediamine) nanoplates. The amount of S vacancies as well as the morphologies of ZnS nanostructures have been controlled by adjusting the hydrolysis time; the layered structure of ZnS(en)_0.5 nanoplates decomposes to yield discrete ZnS nanoparticles at two end facets of template nanoplates, producing barbell-shaped porous and hollow ZnS nanoplates with abundant S vacancies finally. The photocatalytic activity of ZnS nanostructures prepared via hydrolysis for 4 h is 8.2 times higher than that of commercial ZnS. The photocatalytic activity of ZnS nanostructures increases with the increase of emission at 390 nm arising from sulfur vacancies, suggesting that the high photocatalytic efficiency of ZnS nanostructures results mainly from the high amount of sulfur vacancies. Surface defects such as sulfur vacancies can trap photogenerated electrons to block the recombination of charges, enhancing the photocatalytic efficiency of the as-prepared ZnS nanostructures. It has also been found that both ˙OH and ˙O₂^- act as the major reactive species in the photocatalytic decomposition of rhodamine B via our prepared ZnS nanostructures. Barbell-shaped porous and hollow ZnS nanoplates are suggested to have great applicability to photocatalysts in waste-water treatment.

Properties of Zinc Oxide Nanoparticles and Their Activity Against Microbes

Zinc oxide is an essential ingredient of many enzymes, sun screens, and ointments for pain and itch relief. Its microcrystals are very efficient light absorbers in the UVA and UVB region of spectra due to wide bandgap. Impact of zinc oxide on biological functions depends on its morphology, particle size, exposure time, concentration, pH, and biocompatibility. They are more effective against microorganisms such as Bacillus subtilis, Bacillus megaterium, Staphylococcus aureus, Sarcina lutea, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia, Pseudomonas vulgaris, Candida albicans, and Aspergillus niger. Mechanism of action has been ascribed to the activation of zinc oxide nanoparticles by light, which penetrate the bacterial cell wall via diffusion. It has been confirmed from SEM and TEM images of the bacterial cells that zinc oxide nanoparticles disintegrate the cell membrane and accumulate in the cytoplasm where they interact with biomolecules causing cell apoptosis leading to cell death.

Synthesis, Characterisation, and Photocatalytic Behaviour of Mesoporous ZnS Nanoparticles Prepared Using By-Product Templating

High surface area mesoporous ZnS nanoparticles (MZN) were obtained with the aid of the by-product of the synthesising reaction. This by-product, namely NaNO3, can be considered as a soft template responsible for the formation of pores. Ethanol and water were chosen as the synthesis media. Ultrasonic waves were used as an accelerator for the synthesis of MZNs. Photocatalytic activities of the synthesised samples for the degradation of methylene blue (MB) were investigated under ultraviolet irradiation. Synthesised specimens were characterised using field emission scanning electron microscopy, transmission electron microscopy, powder X-ray diffraction, diffuse reflectance spectroscopy, N2-physisorption, and FT-IR spectroscopy. Results indicated that the synthesis media has a pronounced effect on the surface properties of the final porous particles by several mechanisms. The specific surface area of the MZN samples synthesised in water and ethanol were determined to be 53 and 201 m2 g−1, respectively. The difference in the specific surface area was attributed to the weak solvation of S2− ions (Na2S·5H2O in ethanol) and also to the by-product of the synthesis reaction. The photocatalytic behaviour of the mesoporous ZnS nanoparticles synthesised in these two media were investigated and the results have been interpreted with the aid of effective surface area, pore volume, and bandgap energy of the specimens.

Synthesis of porous ZnS, ZnO and ZnS/ZnO nanosheets and their photocatalytic properties

Porous ZnS, ZnO and ZnS–ZnO nanosheets (NSs) are obtained by annealing ZnS(en)_0.5 (en = ethylenediamine) NSs under suitable conditions in air.

Structure-controlled CdS(0D, 1D, 2D) embedded onto 2D ZnS porous nanosheets for highly efficient photocatalytic hydrogen generation

Modulating the CdS morphology with a 1D structure with high conduction band energy can speed up the electron transfer to Pt sites and increase the photocatalytic hydrogen generation rate from 7.7 to 26 mmol g⁻¹ h⁻¹.

Origin of the efficient catalytic thermal decomposition of ammonium perchlorate over (2−1−10) facets of ZnO nanosheets: surface lattice oxygen

A proposed classical catalytic mechanism based on surface lattice oxygen reveals that AP decomposition is promoted more by ZnO nanosheets than ZnS nanosheets.

Synthesis of ZnO nanoparticles using a hydrothermal method and a study its optical activity

ZnO nanoparticles (NPs) with a granular morphology were synthesized using a hydrothermal method. Structural analysis revealed that ZnO NPs had a single crystal wurtzite hexagonal structure. Solvent polarity was responsible for varying and controlling their size and morphology. The process was very trouble free and scalable. In addition, it could be used for fundamental studies on tunable morphology formation. This hydrothermal method showed different morphology with different co-surfactants such as a floral-like or wire-like belt sheet structures etc. Based on their surface morphology, the same material had different applications as a catalyst in various organic reactions and also could be used as a photocatalyst and fuel cell, solar cell or in semiconductors etc. X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visible spectroscopy and photoluminescence of the resulting product was performed to study its purity, morphology and size, plus its optical properties via measurement of band gap energy and light absorbance.

A green process for efficient lignin (biomass) degradation and hydrogen production via water splitting using nanostructured C, N, S-doped ZnO under solar light

Simultaneous photocatalytic hydrogen production (water splitting) and waste lignin (biomass) degradation under visible light has been demonstrated using C, N, S-doped ZnO/ZnS.

Mesoporous single-crystal ZnO nanobelts: supported preparation and patterning

We demonstrate that highly porous ZnO nanobelts can be prepared by thermally decomposing ZnS(en)(0.5) hybrid nanobelts (NBs) synthesized through a solvothermal route using Zn layers deposited on alumina substrates as both the Zn substrate and source. Hybrid decomposition by thermal annealing at 400 °C gives porous ZnS NBs that are transformed by further annealing at 600 °C into wurtzite single crystal ZnO nanobelts with an axial direction of [0001]. The evolution of the morphological and structural transformation ZnS(en)(0.5)→ ZnS → ZnO is investigated at the nanoscale by transmission and scanning electron microscopy analyses. Control of the ZnO NB distributions by patterning the Zn metallization on alumina is achieved as a consequence of the parent hybrid NB patterned growth. The presence of NBs on alumina in a ∼100 μm wide region between Zn stripes allows us to fabricate two contact devices where contact pads are electrically connected through a porous ZnO NB entanglement. Such devices are suitable for employment in photodetectors as well as in gas and humidity sensors.

Geometric Effect of Single or Double Metal-Tipped CdSe Nanorods on Photocatalytic H2 Generation

In the present work, we focused on geometrical (single- or double-tipped) and compositional (Pt or Au) variations of active metal components in a well-defined CdSe nanorod system. These colloidal nanostructures were employed for photocatalytic hydrogen generation from water under the identical reaction conditions with visible light irradiation. The catalysts exhibited significant dependency of the catalytic activity, specifically on the catalyst geometry and the choice of the metal tips, determined by the energetic consideration of electron transfer to the metal tips and hole transfer to the sacrificial reagents on the CdSe nanorods.