The piezoelectricity of functionalized MXenes is of increasingly interest in theoretical and experimental research due to many advantages, such as narrowing the electromechanical coupling size, enhancing the piezoelectric coefficients and producing the out-of-plane piezoelectricity. In this work, employing the first-principle calculations, the piezoelectricity together with related electronic and elastic properties of six functionalized MXenes Sc₂CTT′ monolayers where T and T′ are functional groups were comprehensively investigated. All of them are mechanically stable and more flexible than graphene, indicating their potential use in flexible devices. Furthermore, the semiconducting nature and broken inversion symmetry endow them with piezoelectricity for nanoelectromechanical facilities. In terms of the in-plane piezoelectricity, Sc₂CFCl possesses the biggest d₂₂ and Sc₂COHH has the biggest d₁₅. Sc₂CHCl and Sc₂CFCl monolayers have stronger out-of-plane piezoelectricity when the strain is applied along the x axis due to their larger absolute value of d₃₁ than other monolayers. In addition, with relative to MoSTe which has relatively good out-of-plane piezoelectricity, Sc₂COHF and Sc₂CHCl monolayers possess comparable out-of-plane piezoelectric strain coefficient d₃₃, which is favorable for their applications in out-of-plane piezoelectric sensing. Excitingly, the value of d₃₃ (35.64 pm/V) for Sc₂COHH monolayer is surprisingly over three times of that for MoSTe. It is expected that the studied Sc₂CTT’ monolayers with commendable piezoelectric properties can be utilized in certain nanoelectromechanical systems, such as the blood-pressure meter, bionic skin of robots and energy harvesting equipments.

功能化 MXenes 的压电性由于缩小机电耦合尺寸、提高压电系数和产生面外压电性等诸多优点，在理论和实验研究中越来越受到关注。_{在这项工作中，采用第一性原理计算，六种功能化 MXenes Sc 2}的压电性以及相关的电子和弹性特性全面研究了其中 T 和 T' 是官能团的 CTT' 单分子层。它们都比石墨烯机械稳定且更灵活，表明它们在柔性设备中的潜在用途。此外，半导体性质和破坏的反转对称性赋予它们用于纳米机电设备的压电性。就面内压电性而言，Sc ₂ CFCl 的d ₂₂最大，Sc ₂ COHH 的d ₁₅最大。Sc ₂ CHCl 和 Sc _{2 CFCl 单分子层在沿 x 轴施加应变时具有更强的面外压电性，因为它们的}d ₃₁绝对值较大比其他单层。此外，相对于具有较好面外压电性的MoSTe，Sc ₂ COHF和Sc ₂ CHCl单层具有相当的面外压电应变系数d ₃₃，有利于其在面外的应用。平面压电传感。令人兴奋的是，Sc _{2 COHH 单层的}d ₃₃ (35.64 pm/V)值令人惊讶地是 MoSTe 的三倍多。预计所研究的具有良好压电性能的 Sc ₂ CTT' 单分子层可用于某些纳米机电系统血压计、机器人仿生皮肤、能量采集设备等。