Laser-Induced photothermal activation of multilayer MoS2 with spatially controlled catalytic activity

This study investigates the effects of high-power laser irradiation on multilayer MoS2, a promising material for catalysis, optoelectronics, and energy applications. In addition to previously reported sculpting of MoS2 layers, we discovered a novel effect of laser-induced photothermal heating that drives the chemical activation of MoS2. The photothermal effect was confirmed by temperature-dependent experiments, in situ temperature measurements with nanolocalized probes, and simulations. Remarkably, we observed the reduction of Ag+ ions on laser-irradiated MoS2 layers, forming plasmonic nanostructures without external stimuli such as photons or chemical reducing agents. We attribute this phenomenon to the significant defect density within the laser-carved region and the surrounding area induced by photothermal effects. Further functionalization of the laser-modified MoS2 with 4-nitrobenzenethiol self-assembled monolayers demonstrated a significant increase in photocatalytic activity, close to 100% yield compared to the negligible activity of pristine material. Our findings contribute to a deeper understanding of the light-induced modification of MoS2 properties and introduce a novel method for spatially controlling the chemical activation of MoS2. This advancement holds significant potential in developing high-performance 2D semiconductors as nano-engineered catalytic materials.

Textile Electronics with Laser-Induced Graphene/Polymer Hybrid Fibers

The concept of wearables is rapidly evolving from flexible polymer-based devices to textile electronics. The reason for this shift is the ability of textiles to ensure close contact with the skin, resulting in comfortable, lightweight, and compact "always with you" sensors. We are contributing to this polymer-textile transition by introducing a novel and simple way of laser intermixing of graphene with synthetic fabrics to create wearable sensing platforms. Our hybrid materials exhibit high electrical conductivity (87.6 ± 36.2 Ω/sq) due to the laser reduction of graphene oxide and simultaneous laser-induced graphene formation on the surface of textiles. Furthermore, the composite created between graphene and nylon ensures the durability of our materials against sonication and washing with detergents. Both of these factors are essential for real-life applications, but what is especially useful is that our free-form composites could be used as-fabricated without encapsulation, which is typically required for conventional laser-scribed materials. We demonstrate the exceptional versatility of our new hybrid textiles by successfully recording muscle activity, heartbeat, and voice. We also show a gesture sensor and an electrothermal heater embedded within a single commercial glove. Additionally, the use of these textiles could be extended to personal protection equipment and smart clothes. We achieve this by implementing self-sterilization with light and laser-induced functionalization with silver nanoparticles, which results in multifunctional antibacterial textiles. Moreover, incorporating silver into such fabrics enables their use as surface-enhanced Raman spectroscopy sensors, allowing for the direct analysis of drugs and sweat components on the clothing itself. Our research offers valuable insights into simple and scalable processes of textile-based electronics, opening up new possibilities for paradigms like the Internet of Medical Things.

Laser-Engineered Multifunctional Graphene-Glass Electronics

Glass electronics inspire the emergence of smart functional surfaces. To evolve this concept to the next level, developing new strategies for scalable, inexpensive, and electrically conductive glass-based robust nanocomposites is crucial. Graphene is an attractive material as a conductive filler; however, integrating it firmly into a glass with no energy-intensive sintering, melting, or harsh chemicals has not been possible until now. Moreover, these methods have very limited capability for fabricating robust patterns for electronic circuits. In this work, a conductive (160 OΩ sq^-1 ) and resilient nanocomposite between glass and graphene is achieved via single-step laser-induced backward transfer (LIBT). Beyond conventional LIBT involving mass transfer, this approach simultaneously drives chemical transformations in glass including silicon compound formation and graphene oxide (GO) reduction. These processes take place together with the generation and transfer of the highest-quality laser-reduced GO (rGO) reported to date (Raman intensity ratio I_D /I_G  = 0.31) and its integration into the glass. The rGO-LIBT nanocomposite is further functionalized with silver to achieve a highly sensitive (10^-9  m) dual-channel plasmonic optical and electrochemical sensor. Besides the electrical circuit demonstration, an electrothermal heater is fabricated that reaches temperatures above 300 °C and continuously operates for over 48 h.