Carbon materials exhibit diverse mechanical properties, from hard diamond to soft graphite. However, carbon materials with high ductility are rare, because of strong covalent bonds between carbon atoms. Here, we propose that the structures of triangular lattice have higher ductility than those of hexagonal or quadrangle lattice. A two-dimensional (2D) carbon network, named a carbon Kagome lattice (CKL), is used as an example to verify the point. The carbon structure has a Kagome lattice similar to the triangular lattice. Because empirical potentials cannot well simulate mechanical properties of carbon structures with triangular carbon rings, we work out a neuroevolution potential (NEP) based on a machine learning method. Structural evolution and phase transition under strain have been studied based on the NEP. The results indicate that the ductility of 2D CKL can approach 80%, and even at a high temperature, the ductility can reach 48%. The ductile values are the highest in all 2D crystal materials except the molecular materials. The high ductility is attributed to the phase transition of 2D CKL under tensile strain. It transits to another carbon allotrope, named Carbon Ene-Yne graphyne, which can also sustain a large tensile strain. Our work not only proposes that the materials with triangular lattice have high ductile ability but also finds a 2D carbon material with the highest ductility, extending mechanical applications of materials.

Intelligent gas sensors are indispensable devices widely used in modern society for environmental monitoring, healthcare, the food industry, and public safety. Recent advancements in wireless communication, cloud storage, computing technologies, and artificial intelligence algorithms have significantly enhanced the intelligence level and performance requirements of these sensors. Particularly in the Internet of Things (IoT) environment, flexible and wearable gas sensors are playing an increasingly important role due to their convenience and real-time monitoring capabilities. This review systematically summarizes the latest progress in intelligent gas sensors, covering conceptual frameworks, working principles, and applications across various fields, as well as the construction of IoT networks using sensor arrays. It provides a comprehensive assessment of recent advancements in intelligent gas sensing technologies, highlighting innovations in device architecture, functional mechanisms, and performance in diverse application environments. Special emphasis is placed on transformative developments in flexible and wearable sensor platforms and the enhanced intelligence achieved through the integration of advanced computational algorithms and machine learning techniques. Finally, a summary and future prospects are presented. Despite significant progress, intelligent gas sensors still face challenges related to sensing accuracy, stability, and cost in future applications.

By the Green's function method,we investigate spin transport properties of a zigzag graphene nanoribbon superlattice(ZGNS) under a ferromagnetic insulator and edge effect.The exchange splitting induced by the ferromagnetic insulator eliminates the spin degeneracy,which leads to spin-polarized transport in structure.Spin-dependent minibands and minigaps are exhibited in the conductance profile near the Fermi energy.The location and width of the miniband are associated with the geometry of the ZGNS.In the optimal structure,the spin-up and spin-down minibands can be separated completely near the Fermi energy.Therefore,a wide,perfect spin polarization with clear stepwise pattern is observed,i.e.,the perfect spin-polarized transport can be tuned from spin up to spin down by varying the electron energy.

Flat-band physics has attracted much attention in recent years because of its interesting properties and important applications. Some typical lattices have been proposed to generate flat bands, such as Kagome and Lieb lattices. The flat bands in these lattices contact with other bands rather than being isolated. However, an ideal flat band should be isolated, because isolation is a prerequisite for a number of important applications. Here, we propose a lattice that can produce isolated flat bands. The lattice is named an interlocking-circles lattice because its pattern seems like interlocking circles. Moreover, the lattice is realized in graphene by hydrogenation. In the hydrogenated graphene, there are two nontrivial isolated flat bands appearing around the Fermi level. Upon hole or electron doping, the flat bands split into spin-polarized bands and then result in a ferromagnetic graphene. Our work not only proposes a type of lattice but also opens a way to find systems with isolated flat bands.

We have studied the thermoelectric properties of a 7-atomic-layer ZrGe ₂ N ₄ by first-principles calculations using the Boltzmann transport equation and found that it has excellent stability and thermoelectric properties.

Three-dimensional (3D) carbon networks provide a great platform to search and investigate various topological phases. A lot of nodal-line and nodal-surface topological phases have been found in the 3D carbon networks. However, nodal points are few in them because most carbon networks have high symmetries including inversion symmetry. Here, we propose that nodal points can be generated in low-symmetry carbon structures without inversion symmetry. Two $s{p}^2$-hybridized 3D carbon networks, consisting of distorted six-membered rings and a double helix, respectively, are used as examples to show nodal points. There are several pairs of nodal points locating on the high-symmetry paths of the first Brillouin zone. These nodal points are Dirac points. However, they can also be treated as Weyl points because of the negligibly small spin-orbit coupling in the carbon structures. These nodal points only shift in the momentum space but do not disappear when perturbations such as strains are applied on the carbon structures. We have also studied the topological surface states and found Fermi arcs linking the nodal points. In addition, the synthesis of two carbon networks is discussed.