Photocatalytic activation of molecular oxygen (O₂) is a promising way in oxidative degradation of organic pollutants. However, it suffers from low efficiency mainly due to the limited active sites for O₂ activation over traditional photocatalysts. Therefore, we established a single atomic Ag-g-C₃N₄ (SAACN) catalyst with 10 wt% loading of Ag single sites for boosting the O₂ activation during the degradation of tetracycline (TC), and 10 wt% loading of nanoparticle Ag-g-C₃N₄ (NPACN) was studied as a comparison. When using SAACN, the accumulative concentration of superoxide (•O₂⁻), hydroxyl radical (•OH), singlet oxygen (¹O₂) reached up to 0.66, 0.19, 0.33 mmol L⁻¹h⁻¹, respectively, within 120 min, 11.7, 5.7 and 4.9 times compared with those using NPACN, representing 17.24% of dissolved O₂ was converted to reactive oxygen species (ROS). When additionally feeding air or O_2, the accumulative concentrations of •O₂⁻, •OH, ¹O₂ were even higher (air: 4.21, 0.97, 2.02 mmol L⁻¹ h⁻¹; O₂: 17.13, 1.32, 9.00 mmol L⁻¹ h⁻¹). The rate constants (k) for degrading the TC were 0.0409 min⁻¹ over SAACN and 0.00880 min⁻¹ over NPACN, respectively (mineralization rate: 95.7% vs. 59.9% after 3 h of degradation). Moreover, the degradation ability of SAACN did not decrease in a wide range of pH value (4–10) or under low temperature (10 °C). Besides the high exposure of Ag single sites, other advances of SAACN were: 1(O₂ was more energetic favorable to adsorb on single atomic Ag sites; 2) Positive Ag single sites were easier to obtain the electrons from the surrounding N atoms, and facilitated electron transfer towards adsorbed O₂.

分子氧（O ₂）的光催化活化是氧化降解有机污染物的一种很有前景的方法。然而，它的效率低下主要是由于与传统光催化剂相比，O ₂活化的活性位点有限。因此，我们建立了一种单原子Ag- g -C ₃ N ₄ (SAACN) 催化剂，其负载量为 10 wt% 的 Ag 单点，用于在四环素 (TC) 降解过程中促进 O ₂活化，以及负载量为 10 wt% 的纳米颗粒AG-克-C ₃ ñ ₄（NPACN）进行了研究作为比较。使用 SAACN 时，超氧化物 (•O ₂ ^-)、羟基自由基 (•OH)、单线态氧 ( ¹ O ₂ )在 120 分钟内分别达到 0.66、0.19、0.33 mmol L ^-1 h ^-1，是使用 NPACN 的 11.7、5.7 和 4.9 倍，代表 17.24% 的溶解 O ₂被转化为活性氧 (ROS)。当额外加入空气或O _{2 时，} •O ₂ ^-、•OH、¹ O ₂的累积浓度甚至更高（空气：4.21、0.97、2.02 mmol L ^-1 h ^-1；O ₂：17.13、1.32、9.00 mmol L ^-1 h ^-1 )。速率常数 (ķ）降解的TC为0.0409分钟^-1以上SAACN和0.00880分钟^-1以上NPACN，分别为（矿化速率：95.7％比。后59.9％的降解的3小时）。此外，SAACN 的降解能力在较宽的 pH 值范围（4-10）或低温（10°C）下没有降低。除了Ag单点的高暴露外，SAACN的其他优点是：1（O ₂更有利于吸附在单原子Ag位点上；2）正的Ag单点更容易从周围的N原子中获得电子，和促进电子向吸附的 O ₂转移。