Polymeric carbon nitride (PCN) is an important metal-free photocatalyst for visible light-driven hydrogen peroxide (H₂O₂) production from O₂ reduction. Herein, we synthesized the DPCN catalysts possessing nitrogen defects by one-step thermal polymerization of urea in N₂ stream. As compared to the PCN conventionally synthesized in static air, X-ray photoelectrons spectroscopy (XPS) characterization disclosed that there are more pyridinic N defects in the DPCN catalysts, which is attributed to the removal of a proportion of NH₃ released from urea pyrolysis by flowing N₂. UV–vis diffuse reflectance spectroscopy (UV–vis DRS), Mott–Schottky, steady-state and time-resolved photoluminescence (PL), and electrochemical impedance spectroscopy (EIS) characterizations revealed that the introduction of the nitrogen defects narrows down the band gap, improves the density of the photoexcited charge carriers, prolongs the lifetime of the charge carriers, and enhances the charge transfer efficiency. In visible light-driven photocatalytic O₂ reduction to H₂O₂, the optimal DPCN catalyst afforded an activity of 4.35 times that of the PCN catalyst and a H₂O₂ concentration of 2.83 mmol L^–1 after 10 h of visible light irradiation. This one-step thermal polymerization approach is valid when replacing N₂ stream with Ar and He streams.

_{聚合氮化碳 (PCN) 是一种重要的无金属光催化剂，用于通过 O 2}还原生产可见光驱动的过氧化氢 (H ₂ O ₂ ) 。_{在此，我们通过尿素在N 2}气流中的一步热聚合合成了具有氮缺陷的DPCN催化剂。与常规在静态空气中合成的 PCN 相比，X 射线光电子能谱 (XPS) 表征表明，DPCN 催化剂中存在更多的吡啶 N 缺陷，这归因于尿素热解释放的部分 NH ₃被去除了流动的N ₂. 紫外-可见漫反射光谱 (UV-vis DRS)、莫特-肖特基、稳态和时间分辨光致发光 (PL) 和电化学阻抗谱 (EIS) 表征表明，氮缺陷的引入缩小了带隙，提高了光生载流子的密度，延长了载流子的寿命，提高了电荷转移效率。在可见光驱动的光催化 O ₂还原为 H ₂ O ₂中，最佳 DPCN 催化剂的活性是 PCN 催化剂的 4.35 倍，H ₂ O ₂浓度为 2.83 mmol L ^–1可见光照射 10 h 后。当用Ar 和 He 流代替 N ₂流时，这种一步热聚合方法是有效的。