Two-dimensional materials have been widely studied in recent years due to their excellent properties. In this paper, we investigate the structural, electronic and optical properties of pristine and vacancy defect Hf₂CO₂ using first-principles calculations. The results indicate that O-vacancy (V_O) is energetically more favorable than C-vacancy (V_C) and Hf-vacancy (V_Hf) using analysis of vacancy formation energy and energetic stability. The introductions of V_C and V_Hf result in the transition from semiconductor to metal, while introduction of V_O makes the bandgap of the pristine Hf₂CO₂ (PH) monolayer decrease. The introduction of V_Hf and V_C also results in occurrence of localized defect states. The introduction of V_O effectively enhances the photocatalytic efficiency of the Hf₂CO₂ with V_O (Hf₂CO₂-V_O) monolayer. The PH and Hf₂CO₂-V_O monolayers are semiconductors and have high optical conductivity, strong absorption and reflectivity at 2.5 eV. The charge transfer is also explored.

二维材料由于其优异的性能而在近年来进行了广泛的研究。在本文中，我们使用第一性原理计算研究了原始和空位缺陷Hf ₂ CO ₂的结构，电子和光学性质。结果表明，通过分析空位形成能和能量稳定性，O空位（V _O）在能量上比C空位（V _C）和Hf空位（V _Hf）更有利。V _C和V _Hf的引入导致从半导体到金属的转变，而V _O的引入使原始Hf ₂ CO ₂的带隙（PH）单层降低。V _Hf和V _C的引入还导致出现局部缺陷状态。V _O的引入有效地增强了具有V _O（Hf ₂ CO ₂ -V _O）单层的Hf ₂ CO ₂的光催化效率。PH和Hf ₂ CO ₂ -V _O单层是半导体，在2.5 eV时具有高的光导率，强的吸收性和反射率。还探讨了电荷转移。