Highly Stable Surface-Enhanced Raman Spectroscopy Substrates Using Few-Layer Graphene on Silver Nanoparticles

Graphene can be effectively applied as an ultrathin barrier for fluids, gases, and atoms based on its excellent impermeability. In this work, few-layer graphene was encapsulated on silver (Ag) nanoparticles for the fabrication of highly stable surface-enhanced Raman scattering (SERS) substrates, which has strong resistance to oxidation of the Ag nanoparticles. The few-layer graphene can be successfully grown on the surface of the Ag nanoparticles through a simple heating process. To prevent the agglomeration of the Ag nanoparticles in the fabrication process, poly(methyl methacrylate) (PMMA) layers were used as a solid carbon source instead of methane (CH4) gas generally used as a carbon source for the synthesis of graphene. X-ray diffraction (XRD) spectra of the few-layer graphene-encapsulated Ag nanoparticles indicate that the few-layer graphene can protect the Ag nanoparticles from surface oxidation after intensive annealing processes in ambient conditions, giving the highly stable SERS substrates. The Raman spectra of Rhodamine 6G (R6G) deposited on the stable SERS substrates exhibit maintenance of the Raman signal intensity despite the annealing process in air. The facile approach to fabricate the few-layer graphene-encapsulated Ag nanoparticles can be effectively useful for various applications in chemical and biological sensors by providing the highly stable SERS substrates

Chemical and Physical Pathways for Fabricating Flexible Superamphiphobic Surfaces with High Transparency

Since the discovery of the self-cleaning properties of the lotus effect, the wetting of surfaces were intensively investigated due to their potential application in many industrial sectors. The transparency of flexible liquid repellent coatings are a major industrial problem and their economic consequences are widely known. Hence, a comprehensive understanding of the developments of flexible and transparent superamphiphobic surfaces is required in a number of technological and industrial situations. In this review, we aim to discuss the progress in the design, synthesis, fabrication techniques, and applications of flexible and transparent superamphiphobic surfaces. We start with an introduction, exploring the contact angles and wetting states for superhydrophilic, superhydrophobic, and superoleophobic surfaces, and continue with a review of the wetting transition of such surfaces. Then, we highlight the fabrication techniques involved for the preparation of flexible and transparent superamphiphobic surfaces. This review also discusses the key issues in the fabrication process and surfaces, and their features in improving durability characteristics and self-repellent performance. Then we suggest various recommendations for the improvement of mechanical durability along with potential future directions towards more systematic methods that will also be acceptable for industry. Finally, we conclude with some challenges and potential applications

Textile-Based Electronic Components for Energy Applications: Principles, Problems, and Perspective

Textile-based electronic components have gained interest in the fields of science and technology. Recent developments in nanotechnology have enabled the integration of electronic components into textiles while retaining desirable characteristics such as flexibility, strength, and conductivity. Various materials were investigated in detail to obtain current conductive textile technology, and the integration of electronic components into these textiles shows great promise for common everyday applications. The harvest and storage of energy in textile electronics is a challenge that requires further attention in order to enable complete adoption of this technology in practical implementations. This review focuses on the various conductive textiles, their methods of preparation, and textile-based electronic components. We also focus on fabrication and the function of textile-based energy harvesting and storage devices, discuss their fundamental limitations, and suggest new areas of study

A Highly Sensitive Hydrogen Sensor with Gas Selectivity Using a PMMA Membrane-Coated Pd Nanoparticle/Single-Layer Graphene Hybrid

A polymer membrane-coated palladium (Pd) nanoparticle (NP)/single-layer graphene (SLG) hybrid sensor was fabricated for highly sensitive hydrogen gas (H₂) sensing with gas selectivity. Pd NPs were deposited on SLG via the galvanic displacement reaction between graphene-buffered copper (Cu) and Pd ion. During the galvanic displacement reaction, graphene was used as a buffer layer, which transports electrons from Cu for Pd to nucleate on the SLG surface. The deposited Pd NPs on the SLG surface were well-distributed with high uniformity and low defects. The Pd NP/SLG hybrid was then coated with polymer membrane layer for the selective filtration of H₂. Because of the selective H₂ filtration effect of the polymer membrane layer, the sensor had no responses to methane, carbon monoxide, or nitrogen dioxide gas. On the contrary, the PMMA/Pd NP/SLG hybrid sensor exhibited a good response to exposure to 2% H₂: on average, 66.37% response within 1.81 min and recovery within 5.52 min. In addition, reliable and repeatable sensing behaviors were obtained when the sensor was exposed to different H₂ concentrations ranging from 0.025 to 2%