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The rapid development of 2D material MXenes family brings new opportunities for the application and development of materials science. Here, the structural and electronic properties of WCrC monolayer and its nanoribbons, and the effects of add‐atom adsorption in combination with strain engineering are presented by using first‐principles calculation. The result reveals that pristine WCrC monolayer is always dynamically stable and exhibits metallicity. Within a certain coverage range, the metallic WCrC monolayer can be transformed into semi‐metallic WCrCO2 with dual narrow band gap by adsorbing O atoms, but adsorbed H and Cl atoms cannot change its metal behavior. Moreover, the spin‐splitting of WCrC monolayer is obvious, but when the compressive strain increases to 8%, the energy bands of WCrC monolayer achieve a singular behavior of spin degeneracy. However, neither compressive strain nor tensile strain changes the metallicity of WCrC monolayer. Meanwhile, WCrC nanoribbons with diverse boundaries configurations and edge‐terminated atoms are all metallic, which indicates that boundary configurations and edge‐terminated atoms are not the key factors affecting the metallicity of WCrC nanoribbons. These results suggest that WCrC derivatives are mainly metallic materials, which are expected to be applied in the field of spintronics and may provide new opportunities for the development of metal ion battery electrodes. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) ferromagnetic materials have emerged as one of the hotspots of research in recent years due to their potential applications in magnetic storage and spintronics. In this paper, the electronic structure and optical properties of CrI 3 monolayer (ML) are studied by first-principles calculations. CrI 3 ML is a 2D direct bandgap semiconductor with unique magnetic and electronic properties. Biaxial strain and an external electric field can effectively regulate the physical properties of CrI 3. The results indicate that under biaxial tensile strain, the band gap decreases with increasing strain and gradually smooths out. When an external electric field is applied, the band gap of the CrI 3 ML gradually decreases as the electric field increases, until it transforms into a metallic property at 0.7 V/Å or above. Following that, the optical absorption of CrI 3 under biaxial strain was investigated. Under tensile and compressive strain, the optical absorption peak appeared redshifted in the visible region. In addition, we also designed a nanodevice based on CrI 3 ML to analyze the strain-induced photoconductivity changes. It is observed that the biaxial compressive strain on both the edges of the horizontal and vertical directions can redshift the peak photoconductivity, which means that there is a strong photoelectric response to the red, orange, and green visible regions. Our research will expand the applications of CrI 3 ML in spintronics and optical electronics. CrI 3 ML is a 2D direct bandgap semiconductor with unique magnetic and electronic properties. Both biaxial strain and the applied electric field can modulate the band structure of CrI 3 ML and effectively induce the transition of CrI 3 from semiconductor to metal. Under tensile and compressive strains, the optical absorption peak of CrI 3 ML appears redshifted in the visible region. In addition, we also designed a nanodevice based on CrI 3 ML to analyze the strain-induced photoconductivity changes. CrI 3 ML has a high optical conductivity in the visible light region (green light) and exhibits significant anisotropy when tensile strain is applied. These findings suggest that the 2D CrI 3 structure has great application prospects in spintronic photoelectric sensors. [Display omitted] [ABSTRACT FROM AUTHOR]