Two dimensional (2D) superconductors are important both for the basic understanding of paring mechanism and potential applications in nanosuperconducting quantum interference devices. In this work, we explore the phonon-mediated superconductivity of hole doped and Lithium-deposited monolayer BC₂N by first-principles calculations. Our results reveal that the hole doped planar BC₂N can not superconduct due to a small electron-phonon coupling constant ($\lambda =0.07$). When lithium is deposited on the monolayer, the EPC constant are significantly enhanced to 0.52 and the superconducting transition temperature T_c is determined to be 3.58 K. Because more phonons, in paticular, the out-of-plane modes are triggered to participate in the EPC process, The T_c is higher than 1.4 K of Ca-deposited graphene, 1.3 K of Li-deposited stanene and 3 K of doped WS₂ and NbSe₂. It is also found that tensile biaxial strain weaken the EPC and leads to a decreased superconducting transition temperature. Our findings will provide a new guideline for designing novel 2D superconductors and enrich the potential application of 2D BC₂N.

二维（2D）超导体对于配对机理的基本理解和在纳米超导量子干涉装置中的潜在应用都非常重要。在这项工作中，我们通过第一性原理计算探索了声子介导的空穴掺杂和锂沉积单层BC ₂ N的超导性。我们的结果表明，由于电子声子耦合常数小，空穴掺杂的平面BC ₂ N无法超导（$\lambda =0.07$）。当锂沉积在单分子层上时，EPC常数显着提高到0.52，超导转变温度T _c被确定为3.58K。因为尤其是更多的声子，面外模式被触发参与其中。 EPC工艺中，T _c高于钙沉积的石墨烯的1.4 K，锂沉积的锡的1.3 K和掺杂的WS ₂和NbSe _2的3K 。还发现，拉伸双轴应变削弱了EPC，并导致降低了超导转变温度。我们的发现将为设计新颖的2D超导体提供新的指导，并丰富2D BC ₂ N的潜在应用。