Microwave-assisted solvothermal synthesis of 3D carnation-like SnS2 nanostructures with high visible light photocatalytic activity

Advances in MXene-based technologies for the remediation of toxic phenols: A comprehensive review

The pressing global issue of organic pollutants, particularly phenolic compounds derived primarily from industrial wastes, poses a significant threat to the environment. Although progress has been made in the development of low-cost materials for phenolic compound removal, their effectiveness remains limited. Thus, there is an urgent need for novel technologies to comprehensively address this issue. In this context, MXenes, known for their exceptional physicochemical properties, have emerged as highly promising candidates for the remediation of phenolic pollutants. This review aims to provide a comprehensive and critical evaluation of MXene-based technologies for the removal of phenolic pollutants, focusing on the following key aspects: (1) The classification and categorization of phenolic pollutants, highlighting their adverse environmental impacts, and emphasizing the crucial need for their removal. (2) An in-depth discussion on the synthesis methods and properties of MXene-based composites, emphasizing their suitability for environmental remediation. (3) A detailed analysis of MXene-based adsorption, catalysis, photocatalysis, and hybrid processes, showcasing current advancements in MXene modification and functionalization to enhance removal efficiency. (4) A thorough examination of the removal mechanisms and stability of MXene-based technologies, elucidating their operating conditions and stability in pollutant removal scenarios. (5) Finally, this review concludes by outlining future challenges and opportunities for MXene-based technologies in water treatment, facilitating their potential applications. This comprehensive review provides valuable insights and innovative ideas for the development of versatile MXene-based technologies tailored to combat water pollution effectively.

The photocatalytic reduction of U(VI) by Ag-doped SnS2 materials under visible light

Efficient degradation of uranium(VI) (U(VI)) in wastewater is an urgent problem because of the chemical toxicity and radiotoxicity. In this study, the Ag_x-SnS₂ photocatalysts were compounded by a simple hydrothermal method, effectively removing U(VI) under visible light in water. Compared with SnS₂, the results indicated that Ag_x-SnS₂ would decrease the crystallinity without destroying the crystal structure. Moreover, it has excellent photocatalytic performance on the degradation rate of U(VI). Ag_0.5-SnS₂ exhibited a prominent photocatalytic reduction efficiency of UO₂²⁺ of about 86.4% under optical light for 75 min. This was attributed to Ag-doped catalysts, which can narrow the band gap and enhance absorption in visible light. Meanwhile, the doping of Ag promoted the separation of photoinduced carriers, so that more photogenerated charges participated in the photocatalytic reaction. The stability and reusability were verified by the cycle test and the potential photocatalytic mechanism was analyzed based on the experiment.

Hydrothermal Synthesis of MoS2/SnS2 Photocatalysts with Heterogeneous Structures Enhances Photocatalytic Activity

The use of solar photocatalysts to degrade organic pollutants is not only the most promising and efficient strategy to solve pollution problems today but also helps to alleviate the energy crisis. In this work, MoS₂/SnS₂ heterogeneous structure catalysts were prepared by a facile hydrothermal method, and the microstructures and morphologies of these catalysts were investigated using XRD, SEM, TEM, BET, XPS and EIS. Eventually, the optimal synthesis conditions of the catalysts were obtained as 180 °C for 14 h, with the molar ratio of molybdenum to tin atoms being 2:1 and the acidity and alkalinity of the solution adjusted by hydrochloric acid. TEM images of the composite catalysts synthesized under these conditions clearly show that the lamellar SnS₂ grows on the surface of MoS₂ at a smaller size; high-resolution TEM images show lattice stripe distances of 0.68 nm and 0.30 nm for the (002) plane of MoS₂ and the (100) plane of SnS₂, respectively. Thus, in terms of microstructure, it is confirmed that the MoS₂ and SnS₂ in the composite catalyst form a tight heterogeneous structure. The degradation efficiency of the best composite catalyst for methylene blue (MB) was 83.0%, which was 8.3 times higher than that of pure MoS₂ and 16.6 times higher than that of pure SnS₂. After four cycles, the degradation efficiency of the catalyst was 74.7%, indicating a relatively stable catalytic performance. The increase in activity could be attributed to the improved visible light absorption, the increase in active sites introduced at the exposed edges of MoS₂ nanoparticles and the construction of heterojunctions opening up photogenerated carrier transfer pathways and effective charge separation and transfer. This unique heterostructure photocatalyst not only has excellent photocatalytic performance but also has good cycling stability, which provides a simple, convenient and low-cost method for the photocatalytic degradation of organic pollutants.

New generation advanced nanomaterials for photocatalytic abatement of phenolic compounds

Nowadays, organic pollutants create severe problems worldwide. Phenolic compounds are the harmful pollutants that are developed from industrial effluents, thus causing several environmental problems. Low-cost materials show good potential capabilities for removal of phenolic compounds but are not so effective, so modification is required. New generation nanocatalysts are thought to be excellent for phenol removal. Removal of phenolic pollutants by photodegradation may lead to the decrement of these problematic groups. In this review, (i) a new generation of catalysts for the removal of phenolic compounds is discussed, (ii) nanocatalysts for photodegradation processes, and (iii) the mechanisms involved in photodegradation processes are also discussed. It is noticeable from the analysis that new generation catalysts for photodegradation processes have been demonstrated for high removal abilities of irrefutable phenolic compounds. Finally, future perspectives are also given in this article for the further development of next-generation catalysts.

Facile synthesis of the crescent-like SnS nanocrystals capped by polyvinyl pyrrolidone and its performance of adsorbing dyes

With using Sn²⁺ as tin source, l-cysteine as sulphur source and polyvinyl pyrrolidone (PVP, M_w = 1300000) as surfactant, a novel three-dimensional and crescent-like SnS nanocrystal (NCs) was successfully synthesized in a one-pot hydrothermal method. The as-prepared SnS NCs displayed uniform crescent-like morphological structure, and demonstrated excellent efficiency for the adsorption of cationic dyes such as rhodamine B (RhB) and methylene blue (MB). Kinetic analysis indicated that the adsorption process followed the pseudo second-order model, and the maximum capacity of the SnS NCs to adsorb MB was determined by Langmuir equation to be 252 mg⋅g^-1 at 298 K. The pH dependence of SnS NCs on the adsorption of cationic dyes and the characterization of zeta potential jointly suggested the existence of electrostatic attraction in the process. Overall, this study showed that electrostatic field of functional groups and the capping of PVP could significantly enhance the adsorption performance of the SnS NCs, and also provides a novel insight into the development of highly efficient inorganic adsorbents for cationic dyes.

Accelerated temperature and humidity testing of 2D SnS2 thin films made via four-inch-wafer-scale atomic layer deposition

Tin disulfide (SnS₂) has emerged as a promising two-dimensional (2D) material due to its excellent electrical and optical properties. However, research into 2D SnS₂ has mainly focused on its synthesis procedures and applications; its stability to humidity and temperature has yet to be studied. In this work, 2D SnS₂ thin films were grown by atomic layer deposition (ALD) and characterized by various tools, such as x-ray diffraction, Raman analysis, and transmission electron spectroscopy. Characterization reveals that ALD-grown SnS₂ thin films are a high-quality 2D material. After characterization, a four-inch-wafer-scale uniformity test was performed by Raman analysis. Owing to the quality, large-area growth enabled by the ALD process, 98.72% uniformity was obtained. Finally, we calculated the thermodynamic equations for possible reactions between SnS₂ and H₂O to theoretically presurmise the oxidation of SnS₂ during accelerated humidity and temperature testing. After the accelerated humidity and temperature test, x-ray diffraction, Raman analysis, and Auger electron spectroscopy were performed to check whether SnS₂ was oxidized or not. Our data revealed that 2D SnS₂ thin films were stable at humid conditions.

Ethylene glycol assisted three-dimensional floral evolution of BiFeO3-based nanostructures with effective magneto-electric response

Controlled growth of nanostructures plays a vital role in tuning the physical and chemical properties of functional materials for advanced energy and memory storage devices. Herein, we synthesized hierarchical micro-sized flowers, built by the self-assembly of highly crystalline, two-dimensional nanoplates of Co- and Ni-doped BiFeO3, using a simple ethylene glycol-mediated solvothermal method. Pure BiFeO3 attained scattered one-dimensional nanorods-type morphology having diameter nearly 60 nm. Co-doping of Co and Ni at Fe-site in BiFeO3 does not destabilize the morphology; rather it generates three-dimensional floral patterns of self-assembled nanoplates. Unsaturated polarization loops obtained for BiFeO3 confirmed the leakage behaviour of these rhombohedrally distorted cubic perovskites. These loops were then used to determine the energy density of the BiFeO3 perovskites. Enhanced ferromagnetic behaviour with high coercivity and remanence was observed for these nanoplates. A detailed discussion about the origin of ferromagnetic behaviour based on Goodenough-Kanamori's rule is also a part of this paper. Impedance spectroscopy revealed a true Warburg capacitive behaviour of the synthesized nanoplates. High magneto-electric (ME) coefficient of 27 mV cm-1 Oe-1 at a bias field of -0.2 Oe was observed which confirmed the existence of ME coupling in these nanoplates.

Construction of H4x K2x Sn2-x S4+x /TiO2 nanocomposites with enhanced visible light-driven photocatalytic performance

In this paper, a new photocatalyst with TiO2 nanospheres decorated on ultrathin layered thiostannate H4x K2x Sn2-x S4+x (X = 0.5-0.6, HKTS) nanosheets was successfully synthesized by a facile solvothermal method combined with the hydrolysis of tetrabutyl titanate and it was denoted as HKTS/TiO2. By adjusting the content of tetrabutyl titanate, composites with different Sn/Ti molar ratios were prepared. The composites were applied for RhB degradation under visible light irradiation, and the optimum proportion of HKTS/TiO2 was obtained. The results of X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy and scanning electron microscopy confirmed that TiO2 was successfully decorated on HKTS nanosheets. The combination of TiO2 and HKTS extended the absorption wavelength of TiO2 from UV to visible light range, and the separation efficiency of photoexcited electron-hole pairs was also enhanced. The photocatalytic degradation rate of RhB over HKTS/TiO2-1.0 was almost 97.9% after 60 min illumination, which was higher than those of HKTS and pure TiO2. The photocatalyst exhibited excellent reusability and stability as the degradation rate of RhB was 95.7% even after three cycles. The photocatalytic mechanism experiment indicated that ·O2 - and h+ played a dominant role in the photocatalytic process. All these results indicate that the newly fabricated HKTS/TiO2 composites provide a high-performance photocatalyst for waste water treatment, and the application of thiostannate can be extended to the field of photocatalytic materials.

Highly sensitive NO2 gas sensors based on hexagonal SnS2 nanoplates operating at room temperature

While continuously developing high-performance chemoresistive gas sensors, reducing device power consumption is not negligible. One of the most efficient ways is to enable gas sensors to work close to room temperature. In this work, we present a gas sensor based on hexagonal tin disulfide (SnS₂) nanoplates for sensitive and reversible NO₂ sensing at room temperature. Two-dimensional SnS₂ nanoplates are synthesized via a facile hydrothermal method using Triton X-100 as a surfactant. The sensor exhibits a high response of 15.6 for 50 ppm NO₂ with an experimental limit of detection of 50 ppb at room temperature. Besides, excellent linearity, outstanding selectivity, and reliable long-term stability within 40 d are also demonstrated during the experiment process. The sensing mechanism of this sensor could be explained as the physisorption and charge transfer between NO₂ molecules and SnS₂ nanoplates, which make it possible for the sensor to work at such a low operating temperature. Our research resulted in a SnS₂ nanoplate-based sensor that may pave a new way for effective NO₂ detection in the future.

The green synthesis of PdO/Pd anchored on hierarchical ZnO microflowers with a synthetic effect for the efficient catalytic reduction of 4-nitrophenol

PdO/Pd anchored on hierarchical ZnO microflowers has excellent development potential for treating dye wastewater.

CoS2/TiO2 Nanocomposites for Hydrogen Production under UV Irradiation

Transition metal chalcogenides have intensively focused on photocatalytic hydrogen production for a decade due to their stronger edge and the quantum confinement effect. This work mainly focuses on synthesis and hydrogen production efficiencies of cobalt disulfide (CoS2)-embedded TiO2 nanocomposites. Materials are synthesized by using a hydrothermal approach and the hydrogen production efficiencies of pristine CoS2, TiO2 nanoparticles and CoS2/TiO2 nanocomposites are compared under UV irradiation. A higher amount of hydrogen production (2.55 mmol g-1) is obtained with 10 wt.% CoS2/TiO2 nanocomposite than pristineTiO2 nanoparticles, whereas no hydrogen production was observed with pristine CoS2 nanoparticles. This result unveils that the metal dichalcogenide-CoS2 acts as an effective co-catalyst and nanocrystalline TiO2 serves as an active site by effectively separating the photogenerated electron-hole pair. This study lays down a new approach for developing transition metal dichalcogenide materials with significant bandgaps that can effectively harness solar energy for hydrogen production.

Nanostructured SnS2 Thin Films from Laser Ablated Nanocolloids: Structure, Morphology, Optoelectronic and Electrochemical Properties

Tin disulfide (SnS₂ ) is a binary chalcogenide semiconductor having applications in solar cells, energy storage, and optoelectronics. SnS₂ thin films were deposited by spraying the nanocolloids synthesized by pulsed laser ablation in liquid. The structure, morphology, and optoelectronic properties were studied for films obtained from two liquid media (ethanol and isopropanol) and after heat treatments at various temperatures. X-ray diffraction analysis confirmed the hexagonal crystal structure of the films, whereas the 2-H polytype structure was identified by micro-Raman spectroscopy. Oxidation states of Sn (4+) and S (2-) identified from high resolution X-ray photoelectron spectra confirmed the composition and chemical states of the films. The SnS₂ thin films exhibited distinct porous surface morphologies as the liquid medium in laser ablation was varied. All as-prepared and annealed films showed photoluminescence with a high intensity peak at 485 nm and a low intensity peak at 545 nm. Thin films annealed at 300 °C showed improved electrochemical properties upon illumination using a blue LED light source. Current-voltage curves recorded in dark and light as well as the photoresponse measurements showed their suitability for utilization in optoelectronic devices. The results of this study may trigger further research towards fabrication of nanostructured thin films in large area for optoelectronic and photoelectrochemical applications in an environment friendly and cost-effective way.

SnS2 Nanosheets Coating on Nanohollow Cubic CoS2 /C for Ultralong Life and High Rate Capability Half/Full Sodium-Ion Batteries

Sodium-ion batteries (SIBs) have attracted tremendous interest and become a worldwide research hotpot owing to their low cost and abundant resources. To obtain suitable anode materials with excellent performance for SIBs, an effective and controllable strategy is presented to fabricate SnS₂ nanosheets coating on nanohollow cubic CoS₂ /C (CoS₂ /C@SnS₂ ) composites with a hollow structure using Co-metal-organic frameworks as the starting material. As anodes for SIBs, the CoS₂ /C@SnS₂ electrode exhibits ultralong cycle life and excellent rate performance, which can maintain a high specific capacity of 400.1 mAh g^-1 even after 3500 cycles at a current density of 10 A g^-1 . When used in a full-cell, it also shows enhanced sodium storage properties and delivers a high reversible capacity of 567.3 mAh g^-1 after 1000 cycles at 1 A g^-1 . This strategy can pave a way for preparing various metal sulfides with fascinating structure and excellent performance for the potential application in energy storage area.

Self-assembled three-dimensional flowerlike Mn0.8Cd0.2S microspheres as efficient visible-light-driven photocatalysts for H2 evolution and CO2 reduction

3D flowerlike Mn_0.8Cd_0.2S hierarchical microspheres assembled from nanosheets with excellent photocatalytic activity and stability were fabricated by a facile PVP-assisted solvothermal method.

Effect of sulfur vacancies on the nitrogen photofixation performance of ternary metal sulfide photocatalysts

The NH₄⁺ generation rate over the as-prepared ternary metal sulfide catalysts is linearly related to the sulfur vacancy concentration, confirming that the photocatalytic reduction capacity of N₂ over ternary metal sulfides is highly dependent on the amount of sulfur vacancies.

Preparation of g-C3N4/ZnMoCdS hybrid heterojunction catalyst with outstanding nitrogen photofixation performance under visible light via hydrothermal post-treatment

The outstanding nitrogen photofixation ability of g-C₃N₄/ZnMoCdS heterojunction photocatalyst is attributed to the synergy effect of heterojunctions and sulfur vacancies.

Self-assembly structural transition of protic ionic liquids and P123 for inducing hierarchical porous materials

Hierarchical micro–mesoporous silica–zirconium has been obtained by a simple procedure by adjusting the interaction between protic ionic liquids (NTA) and Pluronic 123 surfactant in acidic media through changing the content of NTA and the pH of the solutions.

Single-Step Synthesis of SnS₂ Nanosheet-Decorated TiO₂ Anatase Nanofibers as Efficient Photocatalysts for the Degradation of Gas-Phase Diethylsulfide

We report on a facile one-step soft hydrothermal process for synthesizing 1D anatase TiO2 nanofibers decorated with ultrathin SnS2 nanosheets. H-titanate nanofibers were used as preshaped Ti precursor. Under controlled conditions, the H-titanate structure was transformed into anatase maintaining the fibril morphology, while at the same time SnS2 nanosheets were grown in situ on the surface of the nanofibers. The successful formation of SnS2 nanosheets on the TiO2 nanofibers was confirmed by high-resolution TEM, and together with XPS spectroscopy, the tight interface formed between the SnS2 and the anatase TiO2 nanofibers was verified. The 1D SnS2/TiO2 hierarchical nanostructures with semiconductor heterojunction were proven to be very efficient under artificial solar irradiation in the photocatalytic degradation of gaseous diethylsulfide as simulant for live yperite chemical warfare agent as well as model substrate for malodorous organosulfide volatile organic compounds. SnS2 did not operate as a visible light sensitizer for TiO2 but rather as an oxidizing agent and charge-carrier separator. The semiconductor ratio in the heterostructure controlled the photoactivity. Samples with no or high content of SnS2 were less active than those with moderate SnS2 content. Enhanced reactivity was ascribed to an efficient separation of the photogenerated charge carriers driven by the differences in band edge positions and favored by the tight interface within the coupled heterostructure.