Strain effects in the electron orbital coupling and electric structure of graphene

Flexible Graphene Field-Effect Transistors and Their Application in Flexible Biomedical Sensing

Flexible electronics are transforming our lives by making daily activities more convenient. Central to this innovation are field-effect transistors (FETs), valued for their efficient signal processing, nanoscale fabrication, low-power consumption, fast response times, and versatility. Graphene, known for its exceptional mechanical properties, high electron mobility, and biocompatibility, is an ideal material for FET channels and sensors. The combination of graphene and FETs has given rise to flexible graphene field-effect transistors (FGFETs), driving significant advances in flexible electronics and sparked a strong interest in flexible biomedical sensors. Here, we first provide a brief overview of the basic structure, operating mechanism, and evaluation parameters of FGFETs, and delve into their material selection and patterning techniques. The ability of FGFETs to sense strains and biomolecular charges opens up diverse application possibilities. We specifically analyze the latest strategies for integrating FGFETs into wearable and implantable flexible biomedical sensors, focusing on the key aspects of constructing high-quality flexible biomedical sensors. Finally, we discuss the current challenges and prospects of FGFETs and their applications in biomedical sensors. This review will provide valuable insights and inspiration for ongoing research to improve the quality of FGFETs and broaden their application prospects in flexible biomedical sensing.

Nanocarbon-based sensors for the structural health monitoring of smart biocomposites

Structural health monitoring (SHM) is a critical aspect of ensuring the safety and durability of smart biocomposite materials used as multifunctional materials. Smart biocomposites are composed of renewable or biodegradable materials and have emerged as eco-friendly alternatives of traditional non-biodegradable glass fiber-based composite materials. Although biocomposites exhibit fascinating properties and many desirable traits, real-time and early stage SHM is the most challenging issue to enable their long-term use. Smart biocomposites are integrated with sensors for in situ identification of the progress of damage and composite failure. The sensitivity of such smart biocomposites is a key functionality, which can be tuned by the introduction of an appropriate filler. In particular, nanocarbons hold promising potential to be incorporated in SHM applications of biocomposites. This review focused on the potential applications of nanocarbons in SHM of biocomposites. The aspects related to fabrication techniques and working mechanism of sensors are comprehensively discussed. Furthermore, their unique mechanical and electrical properties and sustainable nature ensure seamless integration into biocomposites, allowing for real-time monitoring without compromising the material's properties. These sensors offer multi-parameter sensing capabilities, such as strain, pressure, humidity, temperature, and chemical exposure, allowing a comprehensive assessment of biocomposite health. Additionally, their durability and longevity in harsh conditions, along with wireless connectivity options, provide cost-effective and sustainable SHM solutions. As research in this field advances, ongoing efforts seek to enhance the sensitivity and selectivity of these sensors, optimizing their performance for real-world applications. This review highlights the significant advances, ongoing efforts to enhance the sensitivity and selectivity, and performance optimization of nanocarbon-based sensors along with their working mechanism in the field of SHM for smart biocomposites. The key challenges and future research perspectives facing the conversion of nanocarbons to smart biocomposites are also displayed.

Dense arrangement of crown ethers in graphene: novel graphitic carbon oxides with enhanced optoelectronic properties

Incorporating crown ethers into a graphene lattice presents an efficient means of tuning its properties and expanding its range of potential applications. This study employed density functional theory calculations to introduce a series of novel graphitic carbon oxides through the dense arrangement of crown ethers featuring varying cavity sizes within the graphene structure. These newly developed graphitic carbon oxides exhibit thermodynamic and dynamic stability. They also manifest improved stability relative to previously reported graphene oxides with similar oxygen content. Notably, a robust linear relationship is observed between the cohesive energies and the proportion of oxygen atoms. The electronic properties of these graphitic carbon oxides span a spectrum of characteristics, including semi-metallic, metallic, and semi-conducting behavior. Their calculated band gaps range from 0.11 eV to 4.38 eV. Specifically, our analysis reveals that C6G-1, characterized by its largest crown ether-like nanopore with six oxygen atoms, holds potential as a material for photocatalytic water splitting. Moreover, these materials exhibit anisotropic optical properties, showcasing a significant enhancement in absorption within the infrared and visible regions relative to pristine graphene. Given the successful experimental synthesis of crown ether in graphene, we anticipate that our findings will contribute to the widespread utilization of graphene derivatives in low-dimensional electronic, catalytic, and optical devices.

Enhanced visible-light-driven photocatalytic activity in SiPGaS/arsenene-based van der Waals heterostructures

Van der Waals heterostructures (vdWHs) showcase robust and tunable light-matter interactions, establishing an intriguing realm for investigating atomic-scale photocatalytic properties. Here, we employ ab initio methods to study the photocatalytic and optical properties of semiconducting SiPGaS/arsenene-based vdWHs with a type-II band alignment. Across the heterointerfaces, there exists significant built-in electric fields and large potential drop, in turn facilitating the spatial separation of photo-generated electron-hole pairs. These vdWHs further possess high carrier mobility in the order of 102 cm2V⁻1S⁻1, which combining with appropriate band edge positions, endow the vdWHs an absorption coefficient of ∼10⁵ cm⁻1 to harvest a maximal portion of the solar spectrum for visible-light-driven photocatalytic applications. Our findings also reveal transition of the type-II band alignment in a type-III configuration via compressive strain for tunneling field-effect transistor application. Furthermore, both types of vdWHs exhibit enhanced suitability for photocatalysis under conditions with a pH of 2.