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Solar radiation is a sustainable, unlimited source of energy for electricity and chemical reactions, yet the conversion efficiency of actual processes is limited and controlled by photocarriers migration and separation. Enhancing the conversion efficiency would require to suppress the recombination of photogenerated electron–hole pairs and improve the low redox potentials. This can be done during the growth of step-scheme (S-scheme) heterojunctions. Here we review the charge transfer of S-scheme heterojunctions involving a reduction and oxidation photocatalyst in staggered band arrangement with Fermi level differences. We present factors determining the validation of the S-scheme mechanism with respective characterization techniques, including in situ and ex situ experiments, and theoretical studies. We show mechanistic drawbacks of traditional photocatalytic systems to highlight the advantages of S-scheme photocatalysts. We describe co-catalyst loading, bandgap tuning, and interfacial optimization that ultimately achieve highly efficient photocatalysis. Last, application for water splitting, CO2 conversion, pollutant degradation, bacterial inactivation and others is discussed.

Since it was first discovered, thousands of years ago, silkworm silk has been known to be an abundant biopolymer with a vast range of attractive properties. The utilization of silk fibroin (SF), the main protein of silkworm silk, has not been limited to the textile industry but has been further extended to various high-tech application areas, including biomaterials for drug delivery systems and tissue engineering. The outstanding mechanical properties of SF, including its facile processability, superior biocompatibility, controllable biodegradation, and versatile functionalization have allowed its use for innovative applications. In this review, we describe the structure, composition, general properties, and structure-properties relationship of SF. In addition, the methods used for the fabrication and modification of various materials are briefly addressed. Lastly, recent applications of SF-based materials for small molecule drug delivery, biological drug delivery, gene therapy, wound healing, and bone regeneration are reviewed and our perspectives on future development of these favorable materials are also shared.

In this work, we present an ecofriendly, non-hazardous, green synthesis of zinc oxide nanoparticles (ZnO NPs) by leaf extract of Crotalaria verrucosa (C. verrucosa). Total phenolic content, total flavonoid and total protein contents of C. verrucosa were determined. Further, synthesized ZnO NPs was characterized by UV–visible spectroscopy (UV-vis), X-ray diffractometer (XRD), Fourier transform infra-red (FTIR) Spectra, transmission electron microscope (TEM), and Dynamic light scattering (DLS) analysis. UV-vis shows peak at 375 nm which is unique to ZnO NPs. XRD analysis demonstrates the hexagonal phase structures of ZnO NPs. FTIR spectra demonstrates the molecules and bondings associated with the synthesized ZnO NPs and assures the role of phytochemical compounds of C. verrucosa in reduction and capping of ZnO NPs. TEM image exhibits that the prepared ZnO NPs is hexagonal shaped and in size ranged between 16 to 38 nm which is confirmed by DLS. Thermo-gravimetric analysis (TGA) was performed to determine the thermal stability of biosynthesized nanoparticles during calcination. The prepared ZnO NPs showed significant antibacterial potentiality against Gram-positive (S. aureus) and Gram-negative (Proteus vulgaris, Klebsiella pneumoniae, and Escherichia coli) pathogenic bacteria and SEM image shows the generalized mechanism of action in bacterial cell after NPs internalization. In addition, NPs are also found to be effective against the studied cancer cell lines for which cytotoxicity was assessed using MTT assay and results demonstrate highest growth of inhibition at the concentration of 100 µg/mL with IC50 value at 7.07 µg/mL for HeLa and 6.30 µg/mL for DU145 cell lines, in contrast to positive control (C. verrucosa leaf extract) with IC50 of 22.30 µg/mL on HeLa cells and 15.72 µg/mL on DU145 cells. Also, DAPI staining was performed in order to determine the effect on nuclear material due to ZnO NPs treatment in the studied cell lines taking leaf extract as positive control and untreated negative control for comparison. Cell migration assay was evaluated to determine the direct influence of NPs on metastasis that is potential suppression capacity of NPs to tumor cell migration. Outcome of the synthesized ZnO NPs using C. verrucosa shows antimicrobial activity against studied microbes, also cytotoxicity, apoptotic mediated DNA damage and antiproliferative potentiality in the studied carcinoma cells and hence, can be further used in biomedical, pharmaceutical and food processing industries as an effective antimicrobial and anti-cancerous agent.

In recent years, several studies have focused on environmental pollutants. Bisphenol A (BPA) is one prominent industrial raw material, and its extensive utilization and release into the environment constitute an environmental hazard. BPA is considered as to be an endocrine disruptor which mimics hormones, and has a direct relationship to the development and growth of animal and human reproductive systems. Moreover, intensive exposure to the compound is related to prostate and breast cancer, infertility, obesity, and diabetes. Hence, accurate and reliable determination techniques are crucial for preventing human exposure to BPA. Experts in the field have published general electrochemical procedures for detecting BPA. The present timely review critically evaluates diverse chemically modified electrodes using various substances that have been reported in numerous studies in the recent decade for use in electrochemical sensors and biosensors to detect BPA. Additionally, the essential contributions of these substances for the design of electrochemical sensors are presented. It has been predicted that chemically modified electrode-based sensing systems will be possible options for the monitoring of detrimental pollutants.

A bi-metallic titanium–tantalum carbide MXene, Ti x Ta (4−x) C 3 is successfully prepared via etching of Al atoms from parent Ti x Ta (4−x) AlC 3 MAX phase for the first time. X-ray diffractometer and Raman spectroscopic analysis proved the crystalline phase evolution from the MAX phase to the lamellar MXene arrangements. Also, the X-ray photoelectron spectroscopy (XPS) study confirmed that the synthesized MXene is free from Al after hydro fluoric acid (HF) etching process as well as partial oxidation of Ti and Ta. Moreover, the FE-SEM and TEM characterizations demonstrate the exfoliation process tailored by the Ti x Ta (4−x) C 3 MXene after the Al atoms from its corresponding MAX Ti x Ta (4−x) AlC 3 phase, promoting its structural delamination with an expanded interlayer d-spacing, which can allow an effective reversible Li-ion storage. The lamellar Ti x Ta (4−x) C 3 MXene demonstrated a reversible specific discharge capacity of 459 mAhg −1 at an applied C-rate of 0.5 °C with a capacity retention of 97% over 200 cycles. An excellent electrochemical redox performance is attributed to the formation of a stable, promising bi-metallic MXene material, which stores Li-ions on the surface of its layers. Furthermore, the Ti x Ta (4−x) C 3 MXene anode demonstrate a high rate capability as a result of its good electron and Li-ion transport, suggesting that it is a promising candidate as Li-ion anode material.

Transition metal dichalcogenides (TMDs) are promising two-dimensional (2D) materials, and MoS2 has been specifically utilized in electronic devices and integrated circuits. However, the direct synthesis of MoS2 on traditional semiconductors, such as silicon, remains challenging due to the hydrophobic surface of nonoxide wafers (e.g., Si, GaAs, and InP). Herein, a novel, facile, reliable, and one-step method for the direct synthesis of single-crystal MoS2 on a p-Si wafer via hybrid thermolysis is proposed. To demonstrate the applicability of the proposed method, a MoS2/p-Si heterojunction was fabricated and used for solar-driven hydrogen production. The as-fabricated n-MoS2/p-Si heterojunction exhibited a benchmark current density of −13.5 ± 1 mA/cm2 at 0 V and an onset potential of +0.02 V. This method reliably and efficiently produced high-quality MoS2 crystals on a wafer scale and is sufficiently simple to overcome the challenges associated with previous approaches. The method developed herein represents a tremendous advancement in the fabrication of 2D electronic devices.

In this work, we proposed a facile approach to fabricate a superhydrophobic surface for anti-icing performance in terms of adhesive strength and freezing time. A hierarchical structure was generated on as-received Al plates using a wet etching method and followed with a low energy chemical compound coating. Surfaces after treatment exhibited the great water repellent properties with a high contact angle and extremely low sliding angle. An anti-icing investigation was carried out by using a custom-built apparatus and demonstrated the expected low adhesion and freezing time for icephobic applications. In addition, we proposed a model for calculating the freezing time. The experimented results were compared with theoretical calculation and demonstrated the good agreement, illustrating the importance of theoretical contribution in design icephobic surfaces. Therefore, this study provides a guideline for the understanding of icing phenomena and designing of icephobic surfaces.

Low dimensional transition metal carbide and nitride (MXenes) have been emerging as frontier materials for energy storage and conversion. Ti3C2Tx was the first MXenes that discovered and soon become the most widely investigated among the MXenes family. Interestingly, Ti3C2Tx exhibits ultrahigh catalytic activity towards the hydrogen evolution reaction. In addition, Ti3C2Tx is electronically conductive, and its optical bandgap is tunable in the visible region, making it become one of the most promising candidates for the photocatalytic hydrogen evolution reaction (HER). In this review, we provide comprehensive strategies for the utilization of Ti3C2Tx as a catalyst for improving solar-driven HER, including surface functional groups engineering, structural modification, and cocatalyst coupling. In addition, the reaming obstacle for using these materials in a practical system is evaluated. Finally, the direction for the future development of these materials featuring high photocatalytic activity toward HER is discussed.

Venlafaxine (VEN), as one of the popular anti-depressants, is widely utilized for the treatment of major depressive disorder, panic disorder, as well as anxiety. This drug influences the chemicals in the brain, which may result in imbalance in depressed individuals. However, venlafaxine and its metabolites are contaminants in water. They have exerted an adverse influence on living organisms through their migration and transformation in various forms of adsorption, photolysis, hydrolysis, and biodegradation followed by the formation of various active compounds in the environment. Hence, it is crucial to determine VEN with low concentrations in high sensitivity, specificity, and reproducibility. Some analytical techniques have been practically designed to quantify VEN. However, electroanalytical procedures have been of interest due to the superior advantages in comparison to conventional techniques, because such methods feature rapidity, simplicity, sensitivity, and affordability. Therefore, this mini-review aims to present the electrochemical determination of VEN with diverse electrodes, such as carbon paste electrodes, glassy carbon electrodes, mercury-based electrodes, screen-printed electrodes, pencil graphite electrodes, and ion-selective electrodes.

There is actually an intense research in ethanol dry reforming because bioethanol and carbon dioxide, a greenhouse gas, can be converted into syngas and, in turn, into chemicals and energy such as dihydrogen (H2). Here we review dry reforming of ethanol with focus on thermodynamics, catalysts and effect of operating conditions. Noble metal-based catalysts typically exhibit both ethanol and CO2 conversions above 85% in the range of 923‒1073 K, yet the high cost of precious metals has restrained their potential applications. H2 yield of 90% and above is achieved at 1073 K or above due to the endothermic nature of ethanol dry reforming. Improving catalytic performance and inhibiting coke formation may be achieved by using bimetallic catalysts and other types of metal oxides.