Sensing Properties of g-C3N4/Au Nanocomposite for Organic Vapor Detection

A Bi13S18I2-based wearable photoelectrochemical biosensor for accurate monitoring of L-tyrosine in sweat as a diabetes biomarker

The development of real-time, non-invasive, flexible wearable systems for biomarker monitoring is critical for advancing healthcare diagnostics. Herein, we present a flexible patch consisting of an ultrasensitive photoelectrochemical (PEC) biosensor integrated with a hydrophilic nonwoven fabric sweat-collecting pad for precise, unbiased, and high-performance monitoring of L-tyrosine (L-Tyr) in sweat. The innovative PEC sensor is based on the incorporation of Bi13S18I2 (BSI) as a photosensitive material, combined with a molecularly imprinted poly(m-phenylenediamine) (MIP) matrix as a biorecognition element. The developed biosensing photoelectrode exhibits an enhanced photoanodic response and improved incident photon-to-current efficiency (IPCE), attributed to optimized energy band alignment, increased visible-light absorption, efficient photo-induced charge separation, and transfer, extended electron-hole pair lifetime, and enhanced electron density and mobility. The platform offers an impressive linear detection range of 80 nM to 350 μM, with a detection limit as low as 24 nM, ensuring accurate and reliable L-Tyr monitoring, which is essential for diabetes care. The sensor exhibited high repeatability, long-term stability, and low cross-reactivity with potential interfering substances, further demonstrating its practicality for use in complex biological environments. This work marks a significant advancement in wearable diagnostic technology, providing a versatile platform for non-invasive biomarker monitoring. The ability to accurately detect L-Tyr in sweat makes this sensor a valuable tool for real-time health monitoring and diagnostics, opening new avenues for future innovations in PEC sensing and biosensing technologies.

Highly Sensitive Gas and Ethanol Vapor Sensors Based on Carbon Heterostructures for Room Temperature Detection

Graphene oxides (GOs) and hydrogen-terminated nanocrystalline diamonds (H-NCD) have attracted considerable attention due to their unique electronic structure and extraordinary physical and chemical properties in various applications, including gas sensing. Currently, there is a significant focus on air quality and the presence of pollutants (NH3, NO2, etc.), as well as volatile organic compounds (VOC) such as ethanol vapor from industry. This study examines the synthesis of GO, reduced graphene oxide (rGO), thiol-functionalized graphene oxide (SH-GO), and H-NCD thin films and their combination in heterostructures. The materials were analyzed for their ability to detect NO2, NH3, and ethanol vapor at room temperature (22 °C). Among the tested materials, the SH-GO/H-NCD heterostructure exhibited the highest sensitivity, with approximately 630% for ethanol vapor, 41% for NH3 and -19% for NO2. The SH-GO/H-NCD heterostructure also demonstrated reasonable response (272 s) and recovery (34 s) times. Cross-selectivity measurements revealed that the heterostructure's response to ethanol vapor at 100 ppm remained dominant and was minimally affected by the presence of NH3 (100 ppm) or CO2 (100 ppm). The response variations were -1.3% for NO2 and 2.4% for NH3, respectively. These findings suggest that this heterostructure has the potential to be used as an active layer in low-temperature gas sensors. Furthermore, this research proposes a primary mechanism that explains the enhanced sensor response of the heterostructure compared with bare GOs and H-NCD layers.

Harnessing photocatalytic activity of mesoporous graphitic carbon nitride decorated by copper single-atom catalysts for oxidative dehydrogenation of N-heterocycles

This work describes the application of Cu single-atom catalysts (SACs) for photocatalytic oxidative dehydrogenation of N-heterocyclic amines to the respective N-heteroaromatics through environmentally benign and sustainable pathways. The mesoporous graphitic carbon nitride (mpg-C3N4), prepared by the one-step pyrolysis method, possesses a lightweight material with a high surface area (95 m2 g-1) and an average pore diameter (3.6 nm). A simple microwave-assisted preparation method was employed to decorate Cu single-atom over mpg-C3N4 support. The Cu single-atom decorated on mpg-C3N4 support (Cu@mpg-C3N4) is characterized by various characterization techniques, including XRD, UV-visible spectrophotometry, HRTEM, HAADF-STEM with elemental mapping, AC-STEM, ICP-OES, XANES, EXAFS, and BET surface area. These characterization studies confirmed that the Cu@mpg-C3N4 catalyst exhibited high surface area, mesoporous nature, medium band gap, and low metal loading. The as-synthesized and well-characterized Cu@mpg-C3N4 single-atom photocatalyst is then evaluated for its efficacy in converting N-heterocycles into corresponding N-heteroaromatic compounds with excellent conversion and selectivity (>99 %). This transformation is achieved using water as a green solvent and a 30 W white light as a visible light source, demonstrating the catalyst's potential for sustainable and environmentally benign reactions.

Laser-Assisted Preparation of TiO2/Carbon/Ag Nanocomposite for Degradation of Organic Pollutants

The ever-increasing expansion of chemical industries produces a variety of common pollutants, including colors, which become a global and environmental problem. Using a nanocatalyst is one of the effective ways to reduce these organic contaminants. With this in mind, a straightforward and effective method for the production of a novel nanocatalyst based on lignin-derived carbon, titanium dioxide nanoparticles, and Ag particles (TiO2/C/Ag) is described. The preparation of carbon and Ag particles (in sub-micro and nano size) was carried out by laser ablation in air. The nanocomposite was synthesized using a facile magnetic stirrer of TiO2, C, and Ag. According to characterization methods, a carbon nanostructure was successfully synthesized through the laser irradiation of lignin. According to scanning electron microscope images, spherical Ag particles were agglomerated over the nanocomposite. The catalytic activities of the TiO2/C/Ag nanocomposite were tested for the decolorization of methylene blue (MB) and Congo red (CR), employing NaBH4 in a water-based solution at 25 °C. After adding fresh NaBH4 to the mixture of nanocomposite and dyes, both UV absorption peaks of MB and CR completely disappeared after 10 s and 4 min, respectively. The catalytic activity of the TiO2/C/Ag nanocomposite was also examined for the reduction of 4-nitrophenol (4-NP) using a NaBH4 reducing agent, suggesting the complete reduction of 4-NP to 4-aminophenol (4-AP) after 2.30 min. This shows excellent catalytic behavior of the prepared nanocomposite in the reduction of organic pollutants.

Progresses in lignin, cellulose, starch, chitosan, chitin, alginate, and gum/carbon nanotube (nano)composites for environmental applications: A review

Water sources are becoming increasingly scarce, and they are contaminated by industrial, residential, and agricultural waste-derived organic and inorganic contaminants. These contaminants may pollute the air, water, and soil in addition to invading the ecosystem. Because carbon nanotubes (CNTs) can undergo surface modification, they can combine with other substances to create nanocomposites (NCs), including biopolymers, metal nanoparticles, proteins, and metal oxides. Furthermore, biopolymers are significant classes of organic materials that are widely used for various applications. They have drawn attention due to their benefits such as environmental friendliness, availability, biocompatibility, safety, etc. As a result, the synthesis of a composite made of CNT and biopolymers can be very effective for a variety of applications, especially those involving the environment. In this review, we reported environmental applications (including removal of dyes, nitro compounds, hazardous materialsو toxic ions, etc.) of composites made of CNT and biopolymers such as lignin, cellulose, starch, chitosan, chitin, alginate, and gum. Also, the effect of different factors such as the medium pH, the pollutant concentration, temperature, and contact time on the adsorption capacity (AC) and the catalytic activity of the composite in the reduction or degradation of various pollutants has been systematically explained.