Facile synthesis of novel three-dimensional Bi2S3 nanocrystals capped by polyvinyl pyrrolidone to enhance photocatalytic properties under visible light

Insight on photocatalytic synchronous oxidation and reduction for pollutant removal: Chemical energy conversion between macromolecular organic pollutants and heavy metal

Collaborative treatment of pollutants is a promising approach for wastewater treatment. In this work, a covalent organic framework material (COFs) with an imine structure was synthesised by the Schiff base reaction, and photochemical tests showed good photochemical effects. It was used to explore the photocatalytic treatment of co-existing pollutants (heavy metal ions and antibiotics) and the performance of treating co-existing wastewater was investigated. The degradation performance of levofloxacin (LVX) and Cr(VI) was improved in the coexisting pollutants system, with the LVX degradation being 4.2 times more effective than that of the LVX solitary system. Moreover, this phenomenon was also observed in LVX/Ag(I), LVX/Fe(III), sulfadiazine/Cr(VI), norfloxacin/Cr(VI) and tetracycline/Cr(VI) systems. The analysis of active species suggesting that the synergistic promotion of photocatalytic oxidation-reduction systems was not only promoting from the improvement of simple charge separation, but it was also found that high-valent metal species can act directly in the oxidative decomposition of antibiotics. The interaction of pollutants and intermediates were rationally exploited and confirmed by control experiments and theoretical calculation. This conclusion helps us to re-examine the underlying mechanisms of photocatalytic synchronous oxidation and reduction reactions, simultaneously beneficial for the development of mixed pollutant control processes.

Deciphering the mechanistic insights of 4-nitrophenol reduction catalyzed by a 1D-2D Bi2S3 nanostructured catalyst

Exploring the reaction mechanism and the role of a catalyst in the conversion of pollutants to value-added products is vital for sustainable development. Herein, a polyvinylpyrrolidone-assisted liquid-phase reflux strategy was utilized to synthesize anisotropic 1D-2D Bi2S3 nanostructures. The as-synthesized nanostructures were used as catalysts in batch experiments for 4-nitrophenol (4-NP) reduction and they exhibited an apparent rate constant (kapp), turnover frequency (TOF), and activation energy (Ea) of 0.441 min-1, 1.543 h-1 and 26.13 kJ mol-1, respectively. Also, the effects of catalyst dosage, NaBH4 amount, 4-NP concentration, solvents, pH, and common ions were evaluated. Isotope labeling and kinetic isotope effects (KIEs) confirm that water is the proton source in 4-NP reduction. Electrochemical studies revealed that the nanostructured 1D-2D Bi2S3 enables the dissociation of BH4- into active absorbed and adsorbed hydrogen () species and assists in the catalytic reduction of 4-NP. This study offers a new insight into designing an efficient nanostructured 1D-2D Bi2S3 catalyst for 4-nitrophenol reduction.

Leveraging the photocatalytic Cr (VI) reduction by an IRMOF-3@NH2-MIL-101 (Fe) heterostructure based on interfacial Lewis acid-base interaction

A strategy to enhance the photocatalytic performance of metal-organic framework (MOF) based systems for the efficient elimination of Cr(VI) ions from polluted water under visible light irradiation has been developed by constructing MOF@MOF heterojunctions. Specifically, IRMOF-3 was grown in situ around NH2-MIL-101(Fe) based on interfacial Lewis acid-base interaction using 2-aminoterephthalic acid (ATA) as a linker, resulting in the formation of a MOF@MOF heterojunction, designated as IRMOF-3@NH2-MIL-101(Fe). In comparison to individual MOFs, the IRMOF-3@NH2-MIL-101(Fe) heterojunction exhibited a significantly higher photocatalytic reduction efficiency for Cr(VI), achieving a reduction of 95.98% within 120 min under visible-light irradiation. This performance surpasses that of individual MOFs and most reported photocatalysts. Additionally, the mechanism underlying Cr(VI) reduction by IRMOF-3@NH2-MIL-101(Fe) was comprehensively elucidated by analyzing optoelectronic properties, energy band structure, and structural results. It is worth noting that this study represents the first documented instance of photocatalytic Cr(VI) reduction utilizing IRMOF-3 and its interaction with NH2-MIL-101(Fe). The MOF@MOF photocatalyst, leveraging the synergistic effects of its various components, holds great promise for efficiently removing harmful pollutants from water and finds significant potential applications in environmental remediation.

Influencing factors and controlled release kinetics of H2O2 from PVP-coated calcium peroxide NPs for groundwater remediation

Calcium peroxide nanoparticles (nCP) as a versatile and safe solid source of hydrogen peroxide (H2O2) receive substantial attention from researchers as a potential groundwater remediation reagent. In this study, we synthesized polyvinylpyrrolidone-coated calcium peroxide nanoparticles (PVP@nCP-PVP) to control the release rate of H2O2 and modulate pH fluctuation simultaneously. The PVP@nCP-PVP is fully characterized and the H2O2 releasing kinetics and mechanisms are investigated. The H2O2 release longevity of nCP increased with the concentration of controlled release material (CRM) encapsulated shell, while the production of H2O2 decreased inversely. The acidic condition is favorable for increasing H2O2 production by promoting the complex decomposition of nCP. The low temperature prolonged the longevity of nCP and suppressed the competitive side reaction for producing O2. The release of H2O2 is consistent with zero-order reaction kinetics and the release of O2 is consistent with first-order reaction kinetics. At last, different nCP composites were employed to construct a Fenton-like system for the degradation of nitrobenzene (NB). The degradation rate was raised from 57.6% by Fe (II)/nCP to 70.0% and 93.7% by Fe (II)/nCP-PVP and Fe (II)/PVP@nCP-PVP systems, respectively. These findings demonstrate that PVP@nCP-PVP has significant advantages in repairing organically contaminated groundwater. ENVIRONMENTAL IMPLICATION: Groundwater contamination poses a great threat to human health and ecosystems. In-situ chemical oxidation (ISCO) is a widely used groundwater remediation technology. Calcium peroxide (CP) as solid hydrogen peroxide showed merits of low cost and high stability, but the further application was limited due to its violent chemical reaction and short longivity in groundwater . In this work, we prepared polyvinylpyrrolidone-coated controlled release nCP (PVP@nCP-PVP) for modulating the release of H2O2. The investigation of H2O2 release kinetics under various environmental conditions enhances the understanding of the inherent relationship between the H2O2 release performance of controlled-release materials and contamination remediation. The feasibility using macromolecules preparing controlled-release oxidizing agents was confirmed, providing a novel solution for groundwater contamination remediation.

Synergistic effect of a bamboo-like Bi2S3 covered Sm2O3 nanocomposite (Bi2S3-Sm2O3) for enhanced alkaline OER

The availability of hydrogen energy from water splitting through the electrocatalytic route is strongly dependent on the efficiency, durability, and cost of the electrocatalysts. Herein, a novel Bi2S3-covered Sm2O3 (Bi2S3-Sm2O3) nanocomposite electrocatalyst was developed by a hydrothermal route for the oxygen evolution reaction (OER). The electrochemical properties were studied in 1.00 mol KOH solution after coating the target material on the stainless-steel substrate (SS). Physical analysis via XRD, FTIR, IV, TEM/EDX, and XPS revealed that the Bi2S3-Sm2O3 composite possesses metallic surface states, thereby displaying unconventional electron dynamics and purity of phases. The Bi2S3-Sm2O3 composite shows outstanding OER activity with a low overpotential of 197 mV and a Tafel slope of 74 mV dec-1 at a 10 mA cm-2 current density as compared to pure Bi2S3 and Sm2O3. Meanwhile, the composite catalyst retains high stability even after 100 h of the chronoamperometry test. Thus, this work unveils a new avenue for the speedy flow of electrons, which is attributed to the synergetic effect between Bi2S3 and Sm2O3, as well as enriched interfacial defects, which exhibit greater oxygen adsorption capability with improved electronic assemblies in the active interfacial region. In addition, the introduced porous structure in core-shell Bi2S3-Sm2O3 provides extraordinary electrical properties. Thus, this article offers a realistic framework for electrochemical energy generation.

Multifunctional nanoparticle for cancer therapy

Cancer is a complex disease associated with a combination of abnormal physiological process and exhibiting dysfunctions in multiple systems. To provide effective treatment and diagnosis for cancer, current treatment strategies simultaneously focus on various tumor targets. Based on the rapid development of nanotechnology, nanocarriers have been shown to exhibit excellent potential for cancer therapy. Compared with nanoparticles with single functions, multifunctional nanoparticles are believed to be more aggressive and potent in the context of tumor targeting. However, the development of multifunctional nanoparticles is not simply an upgraded version of the original function, but involves a sophisticated system with a proper backbone, optimized modification sites, simple preparation method, and efficient function integration. Despite this, many well-designed multifunctional nanoparticles with promising therapeutic potential have emerged recently. Here, to give a detailed understanding and analyzation of the currently developed multifunctional nanoparticles, their platform structures with organic or inorganic backbones were systemically generalized. We emphasized on the functionalization and modification strategies, which provide additional functions to the nanoparticle. We also discussed the application combination strategies that were involved in the development of nanoformulations with functional crosstalk. This review thus provides an overview of the construction strategies and application advances of multifunctional nanoparticles.

New Formulation to Synthetize Semiconductor Bi2S3 Thin Films Using Chemical Bath Deposition for Optoelectronic Applications

Anisotropic materials possess direction dependent properties as a result of symmetry within their structure. Bismuth sulfide (Bi2S3) is an important semiconductor exhibiting anisotropy due to its crystalline and stratified structure. In this manuscript we present a new and straightforward procedure to deposit Bi2S3 thin films on soda lime glass substrates by the chemical bath deposition (CBD) technique. We studied two fundamental parameters, the time to deposit a single layer and the total number of layers deposited. The single layer deposition time was varied between 70 and 100 min and samples were coated with a total of 1, 2, or 3 layers. It is important to note that a fresh aqueous solution was used for every layer. Visible and near infra-red spectroscopy, scanning electron microscopy, X-ray photoelectrons spectroscopy, and X-ray diffraction were the characterization techniques used to study the resulting films. The calculated band gap values were found to be between 1.56 and 2.1 eV. The resulting Bi2S3 deposited films with the new formulation showed uniform morphology and orthorhombic crystalline structure with an average crystallite size of 19 nm. The thickness of the films varied from 190 to 600 nm in direct correlation to the deposition time and in agreement with the number of layers. The XPS results showed the characteristic bismuth doublet centered around 164.11 and 158.8 eV corresponding with the presence of Bi2S3. The symmetry within the Bi2S3 structure makes it a strong anisotropic crystal with potential applications in optoelectronic and photovoltaic devices, catalysis, and photoconductors among others.

Advances in Hybrid Composites for Photocatalytic Applications: A Review

Heterogeneous photocatalysts have garnered extensive attention as a sustainable way for environmental remediation and energy storage process. Water splitting, solar energy conversion, and pollutant degradation are examples of nowadays applications where semiconductor-based photocatalysts represent a potentially disruptive technology. The exploitation of solar radiation for photocatalysis could generate a strong impact by decreasing the energy demand and simultaneously mitigating the impact of anthropogenic pollutants. However, most of the actual photocatalysts work only on energy radiation in the Near-UV region (<400 nm), and the studies and development of new photocatalysts with high efficiency in the visible range of the spectrum are required. In this regard, hybrid organic/inorganic photocatalysts have emerged as highly potential materials to drastically improve visible photocatalytic efficiency. In this review, we will analyze the state-of-art and the developments of hybrid photocatalysts for energy storage and energy conversion process as well as their application in pollutant degradation and water treatments.

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.

Evaluation of synergistic effect from Ag-AgCl1/3Br1/3I1/3 composite on photocatalytic degradation the oil field pollutants

A series of Ag/AgX (X = Cl, Br, I; X = Cl, Br, or X = Cl, I, or X = Br, I; X = Cl, Br, and I) composite photocatalysts were synthesized via a facile photoreduction. The several characterization methods of X-ray diffraction (XRD), energy dispersive X-ray spectrometry (EDS) mapping and X-ray photoelectron spectroscopy (XPS) were characterized the samples. Through evaluation the photocatalytic activity of degradation rhodamine, methyl orange, and phenol, Ag-AgCl_1/3Br_1/3I_1/3 exhibited the superior selective photocatalytic activities than other photocatalysts. The reason for improved photocatalytic property of Ag-AgCl_1/3Br_1/3I_1/3 was attributed to the multifarious halogen atoms with the synergistic effect and the surface plasmon resonance (SPR) effect of Ag⁰. Furthermore, the recycle experiments were conducted to reveal the stability and reusability, the trapping experiments confirmed the active species of Ag-AgCl_1/3Br_1/3I_1/3.

Hedgehog-like Bi2S3 nanostructures: a novel composite soft template route to the synthesis and sensitive electrochemical immunoassay of the liver cancer biomarker

A new route was proposed to synthesize novel hedgehog-like Bi₂S₃nanostructure using CTAB-trimellitic acid as a composite soft template and thiourea as the sulfur source, which was used  to construct an effective electrochemical AFP immunosensor.