氧掺杂g-C3N4光催化降解Cu-EDTA络合物的反应机理研究

Mechanism study of the photocatlytic decomplexation of Cu-EDTA over oxygen doped g-C_3N_4

本研究以Cu-EDTA为模拟污染物,探讨了非金属石墨相氮化碳(g-C_3N_4)在光催化降解重金属络合污染物中的应用潜力.首先采用在空气气氛下煅烧的方式对g-C_3N_4进行氧掺杂改性,并通过XRD、TEM和DRS等表征手段对掺杂前后的催化剂结构进行表征.光催化性能评价结果表明,氧掺杂改性更有利于催化剂表面光生空穴的分离,从而呈现出显著提升的破络合能力.通过自由基猝灭实验对g-C_3N_4光降解Cu-EDTA的催化机制进行了研究,结果表明,未掺杂g-C_3N_4通过O_2^(·-)、空穴和·OH的共同作用实现重金属络合物的去除,而氧掺杂样品以具有更强破络合能力的光生空穴为主要活性物种实现Cu-EDTA污染物的降解.

In this study,Cu-EDTA was used as a model contaminant to demonstrate the feasibility of using carbon nitride for the photocatalytic decomplexation of heavy metal complexes. To improve the activity of g-C3N4,a facile air calcination procedure was used to fabricate oxygen doped g-C3N4. XRD,TEM and UV-vis DRS were used to study the microstructures of g-C3N4 before and after oxygen doping. Photodegradation experiments indicated that oxygen doping could improve the interfacial separation of photogenerated holes. As a result,g-C3N4-O exhibited significantly enhanced photoactivity for the decomplexation of Cu-EDTA. The photocatalytic mechanism was investigated by the reactive species trapping experiments. It was found that Cu-EDTA could be photodegraded by O2^（·-）,·OH and holes over pristine g-C3N4. Differently,photogenerated holes were the dominant reactive species for the decomplexation reactions over oxygen doped photocatalysts.