Novel Gas Sensing Approach: ReS2/Ti3C2Tx Heterostructures for NH3 Detection in Humid Environments.

Continuous monitoring of ammonia (NH3) in humid environments poses a notable challenge for gas sensing applications because of its effect on sensor sensitivity. The present work investigates the detection of NH3 in a natural humid environment utilizing ReS2/Ti3C2Tx heterostructures as a sensing platform. ReS2 nanosheets were vertically grown on the surface of Ti3C2Tx sheets through a hydrothermal synthetic approach, resulting in the formation of ReS2/Ti3C2Tx heterostructures. The structural, morphological, and optical properties of ReS2/Ti3C2Tx were investigated using various state-of-the-art techniques, including scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, zeta potential, Brunauer-Emmett-Teller technique, and Raman spectroscopy. The heterostructures exhibited 1.3- and 8-fold increases in specific surface area compared with ReS2 and Ti3C2Tx, respectively, potentially enhancing the active gas adsorption sites. The electrical investigations of the ReS2/Ti3C2Tx-based sensor demonstrated enhanced selectivity and superior sensing response ranging from 7.8 to 12.4% toward 10 ppm of NH3 within a relative humidity range of 15-85% at room temperature. These findings highlight the synergistic effect of ReS2 and Ti3C2Tx, offering valuable insights for NH3 sensing in environments with high humidity, and are explained in the gas sensing mechanism.

Lignin-Based Platform as a Potential Low-Cost Sorbent for the Direct Air Capture of CO2.

The urgent need to address the current climate crisis has led to concerted efforts to develop low-cost and sustainable methods to remove carbon dioxide from the atmosphere. Carbon capture and storage (CCS) and negative emissions technologies (NET's) offer the most promising paths forward to offsetting global emissions. In this study, we explore the potential of kraft lignin, a readily available biomaterial, as a low-cost alternative for the development of a CO2 sorbent. The approach leverages the known ability of amines to reacting with carbon dioxide and forming a stable compound. Commercially available kraft lignin was modified with diethylenetriamine (DETA), triethylenetetramine (TETA), and tetraethylenepentamine (TEPA) using a one-pot synthesis approach via the Mannich reaction. The sorbent was evaluated for porosity, accessible amine density, and nitrogen content. The CO2 capture experiments revealed that the resulting sorbent can capture 0.80 (±0.03) mmol of CO2 per gram of sorbent.

Fabrication of Rhenium Disulfide/Mesoporous Silica Core-Shell Nanoparticles for a pH-Responsive Drug Release and Combined Chemo-Photothermal Therapy.

A stimuli-responsive drug delivery nanocarrier with a core-shell structure combining photothermal therapy and chemotherapy for killing cancer cells was constructed in this study. The multifunctional nanocarrier ReS2@mSiO2-RhB entails an ReS2 hierarchical nanosphere coated with a fluorescent mesoporous silica shell. The three-dimensional hierarchical ReS2 nanostructure is capable of effectively absorbing near-infrared (NIR) light and converting it into heat. These ReS2 nanospheres were generated by a hydrothermal synthesis process leading to the self-assembly of few-layered ReS2 nanosheets. The mesoporous silica shell was further coated on the surface of the ReS2 nanospheres through a surfactant-templating sol-gel approach to provide accessible mesopores for drug uploading. A fluorescent dye (Rhodamine B) was covalently attached to silica precursors and incorporated during synthesis in the mesoporous silica walls toward conferring imaging capability to the nanocarrier. Doxorubicin (DOX), a known cancer drug, was used in a proof-of-concept study to assess the material's ability to function as a drug delivery carrier. While the silica pores are not capped, the drug molecule loading and release take advantage of the pH-governed electrostatic interactions between the drug and silica wall. The ReS2@mSiO2-RhB enabled a drug loading content as high as 19.83 mg/g doxorubicin. The ReS2@mSiO2-RhB-DOX nanocarrier's cumulative drug release rate at pH values that simulate physiological conditions showed significant pH responsiveness, reaching 59.8% at pH 6.8 and 98.5% and pH 5.5. The in vitro testing using HeLa cervical cancer cells proved that ReS2@mSiO2-RhB-DOX has a strong cancer eradication ability upon irradiation with an NIR laser owing to the combined drug delivery and photothermal effect. The results highlight the potential of ReS2@mSiO2-RhB nanoparticles for combined cancer therapy in the future.

Lignin-Based Nanospheres as Environmental Remediation Platforms for Anionic Dye Contaminants.

Modern manufacturing of textiles, pharmaceuticals, food, cosmetics, plastics, paper, etc. involves the utilization of anionic and cationic dyes that lead to significant water contamination. Recent research has explored the use of nanomaterials toward developing nanoadsorbents for water decontamination caused by industrial pollution. Here, we report on a novel platform for anionic dye remediation, consisting of a polyethylenimine-functionalized lignin nanosphere (PEI-LNS). The designed nanomaterial shows significant ability to adsorb an anionic dye selected as a proof-of-concept-Sulforhodamine B, from aqueous solutions. The PEI lignin nanoadsorbents (PEI-LNS) showed a better ability to adsorb Sulforhodamine B sodium salt (SBSS) when compared to the raw lignin nanosphere adsorbent (LNS), especially in acidic conditions. The nanomaterial was characterized through transmission electron microscopy, scanning electron microscopy, Brunauer-Emmett-Teller surface area analysis, elemental analysis, zeta potential, thermogravimetric analysis, Fourier transform infrared spectroscopy, and nuclear magnetic resonance. The impacts of ionic strength, contact time, pH, and adsorbent concentration have been evaluated. The ability of PEI-LNS to adsorb SBSS was found to be consistent with Langmuir isotherms and pseudo-second-order kinetic models. The PEI-LNS could be recycled three times, reaching a good (85%) adsorbing capacity even in the third cycle. The study demonstrates that PEI-LNS has a strong affinity as a novel adsorbent for anionic dyes and could be employed in environmental cleanups pertaining to such contaminations.

Infrared-Activated Bactericide: Rhenium Disulfide (ReS2)-Functionalized Mesoporous Silica Nanoparticles.

An attractive strategy for treating bacterial infection is the combination of antibiotic chemotherapy with photothermal therapy (PTT), which could be implemented using multifunctional nanomaterials. In this work, the intrinsic photothermal efficiency of two-dimensional (2D) rhenium disulfide (ReS2) nanosheets is enhanced by their coating on mesoporous silica nanoparticles (MSNs) to realize a highly efficient light-responsive nanoparticle endowed with controlled-release drug delivery capability, denoted as MSN-ReS2. The MSN component of the hybrid nanoparticle features augmented pore size toward facilitating increased loading of antibacterial drugs. The ReS2 synthesis is conducted in the presence of MSNs through an in situ hydrothermal reaction and leads to a uniform surface coating of the nanosphere. The MSN-ReS2 bactericide testing showed more than 99% bacterial killing efficiency in both Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus) upon laser irradiation. A cooperative effect that led to a 100% bactericide effect on Gram-negative bacteria (E. coli) was observed when tetracycline hydrochloride was loaded in the carrier. The results show the potential of MSN-ReS2 to be used as a wound-healing therapeutic with a synergistic bactericide role.