Controllable edge modification of multi-layer graphene for improved dispersion stability and high electrical conductivity

Immobilization of Enzyme Electrochemical Biosensors and Their Application to Food Bioprocess Monitoring

Electrochemical biosensors based on immobilized enzymes are among the most popular and commercially successful biosensors. The literature in this field suggests that modification of electrodes with nanomaterials is an excellent method for enzyme immobilization, which can greatly improve the stability and sensitivity of the sensor. However, the poor stability, weak reproducibility, and limited lifetime of the enzyme itself still limit the requirements for the development of enzyme electrochemical biosensors for food production process monitoring. Therefore, constructing sensing technologies based on enzyme electrochemical biosensors remains a great challenge. This article outlines the construction principles of four generations of enzyme electrochemical biosensors and discusses the applications of single-enzyme systems, multi-enzyme systems, and nano-enzyme systems developed based on these principles. The article further describes methods to improve enzyme immobilization by combining different types of nanomaterials such as metals and their oxides, graphene-related materials, metal-organic frameworks, carbon nanotubes, and conducting polymers. In addition, the article highlights the challenges and future trends of enzyme electrochemical biosensors, providing theoretical support and future perspectives for further research and development of high-performance enzyme chemical biosensors.

Molecular Dynamics Simulation for the Effect of Fluorinated Graphene Oxide Layer Spacing on the Thermal and Mechanical Properties of Fluorinated Epoxy Resin

Traditional epoxy resin (EP) materials have difficulty to meet the performance requirements in the increasingly complex operating environment of the electrical and electronic industry. Therefore, it is necessary to study the design and development of new epoxy composites. At present, fluorinated epoxy resin (F-EP) is widely used, but its thermal and mechanical properties cannot meet the demand. In this paper, fluorinated epoxy resin was modified by ordered filling of fluorinated graphene oxide (FGO). The effect of FGO interlayer spacing on the thermal and mechanical properties of the composite was studied by molecular dynamics (MD) simulation. It is found that FGO with ordered filling can significantly improve the thermal and mechanical properties of F-EP, and the modification effect is better than that of FGO with disordered filling. When the interlayer spacing of FGO is about 9 Å, the elastic modulus, glass transition temperature, thermal expansion coefficient, and thermal conductivity of FGO are improved with best effect. Furthermore, we calculated the micro parameters of different systems, and analyzed the influencing mechanism of ordered filling and FGO layer spacing on the properties of F-EP. It is considered that FGO can bind the F-EP molecules on both sides of the nanosheets, reducing the movement ability of the molecular segments of the materials, so as to achieve the enhancement effect. The results can provide new ideas for the development of high-performance epoxy nanocomposites.

Highly efficient heterojunction solar cells enabled by edge-modified tellurene nanoribbons

Tellurene, a two-dimensional (2D) semiconductor, meets the requirements for optoelectronic applications with desirable properties, such as a suitable band gap, high carrier mobility, strong visible light absorption and high air stability. Here, we demonstrate that the band engineering of zigzag tellurene nanoribbons (ZTNRs) via edge-modification can be used to construct highly efficient heterojunction solar cells by using first-principles density functional theory (DFT) calculations. We find that edge-modification enhances the stability of ZTNRs and halogen-modified ZTNRs showing suitable band gaps (1.35-1.53 eV) for sunlight absorption. Furthermore, the band gaps of ZTNRs with tetragonal edges do not strongly depend on the edge-modification and ribbon width, which is conducive to experimental realization. The heterojunctions constructed by halogen-modified ZTNRs show desirable type 2 band alignments and small band offsets with reduced band gaps and enhanced sunlight absorption, resulting in high power conversion efficiency (PCE) in heterojunction solar cells. In particular, the calculated maximum PCE of designed heterojunction solar cells based on halogen-modified ZTNRs can reach as high as 22.6%.