Real-time monitoring of volatile organic compounds (VOCs) is crucial for both industrial production and daily life. However, the non-reactive nature of VOCs and their low concentrations pose a significant challenge for developing sensors. In this study, we investigated the adsorption behaviors of typical VOCs (C₂H₄, C₂H₆, and C₆H₆), on pristine and Pt-decorated SnS monolayers using density functional theory (DFT) calculations. Pristine SnS monolayers have limited charge transfer and long adsorption distances to VOC molecules, resulting in VOC insensitivity. The introduction of Pt atoms promotes charge transfer, creates new energy levels, and increases the overlap of the density of states, thereby enhancing electron excitation and improving gas sensitivity. Pt-decorated SnS monolayers exhibited high sensitivities of 241,921.7%, 35.7%, and 74.3% towards C₂H₄, C₂H₆, and C₆H₆, respectively. These values are 142,306.9, 23.8, and 82.6 times higher than those of pristine SnS monolayers, respectively. Moreover, the moderate adsorption energies of adsorbing C₂H₆ and C₆H₆ molecules ensure that Pt-decorated SnS monolayers possess good reversibility with a short recovery time at 298 K. When heated to 498 K, C₂H₄ molecules desorbs from the surface of Pt-decorated SnS monolayer in 162.33 s. Our results indicate that Pt-decorated SnS monolayers could be superior candidates for sensing VOCs with high selectivity, sensitivity, and reversibility.

This study explores the potential of MoS₂ monolayers as heavy metal sensors for As, Cd, Hg, and Pb using density functional theory (DFT) and Non-Equilibrium Green’s Function (NEGF) simulations. Our findings reveal that As and Pb adsorption significantly alters the surface structure and electronic properties of MoS₂, introducing impurity levels and reducing the band gap. Conversely, Cd and Hg exhibit weaker interactions with the MoS₂ surface. The MoS₂ monolayer sensors demonstrate exceptional sensitivity for all four target heavy metals, with values reaching 126,452.28% for As, 1862.67% for Cd, 427.71% for Hg, and 83,438.90% for Pb. Additionally, the sensors demonstrate selectivity for As and Pb through distinct response peaks at specific bias voltages. As and Pb adsorption also induces magnetism in the MoS₂ system, potentially enabling magnetic sensing applications. The MoS₂ monolayer’s moderate adsorption energy facilitates rapid sensor recovery at room temperature for As, Hg, and Cd. Notably, Pb recovery time can be significantly reduced at elevated temperatures, highlighting the reusability of the sensor. These results underscore the potential of MoS₂ monolayers as highly sensitive, selective, and regenerable sensors for real-time heavy metal detection.

Water-in-oil droplet generation for object encapsulation is of increasing importance in biochemical reaction, drug diagnostics, and environmental science. Optofluidic technique is a powerful tool for manipulating mesoscopic particles and droplets within a continuous liquid phase. Here, we report a flexible and miniaturized droplet generator based on a microvortex chip by light-heat energy conversion to fuse, trap, and release picoliter aqueous droplets in the immiscible carrier oil. The droplet sizes in the generators can be tuned by the flow rate of the vortices. Further, it is demonstrated that the generated droplet can realize size-selective encapsulation of micro-matters with tunable rotating trajectories. The results showed that the microvortex-based droplet generator propose a method for the stable fusion and encapsulation of droplet with controllable positions and volumes. This system will provide a controllable microfluidic environment for droplet tweezers, micro-reactors, micro-mixers, and object encapsulation in practical applications.

This study explores the potential of β-SnSe monolayers as a promising material for ozone (O₃) sensing using density functional theory (DFT) combined with the non-equilibrium Green’s function (NEGF) method. The adsorption characteristics of O₃ molecules on the β-SnSe monolayer surface were thoroughly investigated, including adsorption energy, band structure, density of states (DOSs), differential charge density, and Bader charge analysis. Post-adsorption, hybridization energy levels were introduced into the system, leading to a reduced band gap and increased electrical conductivity. A robust charge exchange between O₃ and the β-SnSe monolayer was observed, indicative of chemisorption. Recovery time calculations also revealed that the β-SnSe monolayer could be reused after O₃ adsorption. The sensitivity of the β-SnSe monolayer to O₃ was quantitatively evaluated through current-voltage characteristic simulations, revealing an extraordinary sensitivity of 1817.57% at a bias voltage of 1.2 V. This sensitivity surpasses that of other two-dimensional materials such as graphene oxide. This comprehensive investigation demonstrates the exceptional potential of β-SnSe monolayers as a highly sensitive, recoverable, and environmentally friendly O₃ sensing material.

单层CuSe属于体相为非层状的二维材料，由于本质上是具有金属性质的，不适合在电子器件中应用。本文通过外部原子修饰的方法实现CuSe的电子结构的改变，采用密度泛函理论的第一性原理研究了单层CuSe在顶位、中心和桥位添加第二周期原子后的能带结构，重点分析了单层CuSe添加Li和B原子的电子结构，包括能带结构、态密度、差分电荷密度和晶体轨道哈密顿布居分析。结果发现：添加Li原子后，从能带结构的结果来看，三个位置都能实现CuSe由金属性转为半导体性，且Li原子更倾向修饰在CuSe的六角形中心，带隙约为1.77eV；在Cu原子的顶部位置添加B原子也可以实现CuSe具有半导体性，带隙约为1.2eV。通过差分电荷密度和晶体轨道哈密顿布居的结果来看，B原子用B-Se极性共价键结合在单层CuSe的顶部。第一原理揭示了从单层CuSe到CuXSe（X=Li，B）的金属到半导体转变的实现，计算结果使CuSe在未来的电子设备中使用成为可能。