Photo-oxidation with semiconductor photocatalysts provides a sustainable and green solution for NO_x elimination. Nevertheless, the utilization of traditional photocatalysts in efficient and safe photocatalytic NO_x removal is still a challenge due to the slow charge kinetic process and insufficient optical absorption. In this paper, we report a novel porous g-C₃N₄ nanosheet photocatalyst modified with cyano defects and CaCO₃ (xCa-CN). The best performing sample (0.5Ca-CN) exhibits an enhanced photo-oxidation NO removal rate (51.18 %) under visible light irradiation, largely surpassing the value of pristine g-C₃N₄ nanosheets (34.05 %). Such an enhancement is mainly derived from an extended visible-light response, improved electron excitation and transfer, which are associated with the synergy of cyano defects and CaCO₃, as evidenced by a series of spectroscopic analyses. More importantly, in-situ DRIFTS and density functional theory (DFT) results suggest that the introduction of cyano defects and CaCO₃ enables control over NO adsorption and activation processes, making it possible to implement a preference pathway (NO → NO⁺ → NO₃¯) and reduce the emission of toxic intermediate NO₂. This work demonstrates the potential of integrating defect engineering and insulator modification to design highly efficient g-C₃N₄-based photocatalysts for air purification.

使用半导体光催化剂进行光氧化为 NO _x消除提供了可持续的绿色解决方案。然而，由于充电动力学过程缓慢且光吸收不足，传统光催化剂在高效、安全的光催化 NO _x去除中的应用仍然是一个挑战。在本文中，我们报道了一种用氰基缺陷和CaCO ₃ ( x Ca-CN)修饰的新型多孔gC ₃ N _{4纳米片光催化剂。}性能最佳的样品（0.5Ca-CN）在可见光照射下表现出更高的光氧化 NO 去除率（51.18 %），大大超过原始 gC ₃ N _4的值纳米片 (34.05%)。这种增强主要来自扩展的可见光响应、改进的电子激发和转移，这与氰基缺陷和 CaCO ₃的协同作用有关，一系列光谱分析证明了这一点。更重要的是，原位 DRIFTS 和密度泛函理论 (DFT) 结果表明，氰基缺陷和 CaCO ₃的引入能够控制 NO 的吸附和活化过程，从而可以实现偏好途径 (NO → NO ⁺ → NO ₃ ¯)，减少有毒中间体NO ₂的排放。这项工作展示了整合缺陷工程和绝缘体修改以设计高效 gC 的潜力用于空气净化的₃ N _{4基光催化剂。}