Visible-light photocatalytic activity and photo-corrosion mechanism of Ag3PO4/g-C3N4/PVA composite film in degrading gaseous toluene
Visible-light photocatalytic activity and photo-corrosion mechanism of Ag3PO4/g-C3N4/PVA composite film in degrading gaseous toluene
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DOI：
10.1016/j.cattod.2019.03.046
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发表时间：
2019-09
期刊：
影响因子：
5.3
通讯作者：
R. Cheng;Junying Wen;Jincheng Xia;ZhuoYuan Li;Wen-Jin Sun;Liang-jie Shen;Lei Shi;Xiang Zheng
中科院分区：
文献类型：
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作者：
R. Cheng;Junying Wen;Jincheng Xia;ZhuoYuan Li;Wen-Jin Sun;Liang-jie Shen;Lei Shi;Xiang Zheng
Ag_3PO_4半导体光催化剂是一种性能优良的光催化剂。但Ag 3 PO 4的光腐蚀性和稳定性限制了其应用。采用离子交换法和溶剂共混法制备了一系列Ag 3 PO 4/g-C3 N4/PVA复合膜，并将其用于可见光下甲苯的降解。材料表征表明，Ag 3 PO 4颗粒成功地沉积在g-C3 N4表面。气相甲苯降解实验结果表明，2.6%-Ag 3 PO 4/g-C3 N4/PVA复合材料具有较好的上级光催化性能，其降解效率分别是g-C3 N4/PVA和Ag 3 PO 4/PVA的1.35倍和1.26倍。此外，还对x%-Ag 3 PO 4/g-C3 N4/PVA复合材料的变色进行了检测，并对变色机理进行了探讨。在复合材料表面检测到Ag°，表明Ag 3 PO 4中的Ag+通过与H2O分子反应被还原为Ag°（称为光腐蚀）。PVA涂层对复合材料表面的光腐蚀起着重要的作用，PVA将水分子吸附到复合材料表面。而PVA包覆在Ag 3 PO 4表面，通过在Ag 3 PO 4表面生成·OH，形成化学交联网络，进一步保护Ag 3 PO 4免受光腐蚀。空气中的湿度是导致Ag 3 PO 4光腐蚀的主要原因，从而导致复合材料的光催化性能急剧下降。与低湿度（6%）体系相比，2.6%-Ag 3 PO 4/g-C3 N4/PVA复合膜在高湿度（70%）下降解甲苯气体的稳定性急剧下降。本研究为Ag 3 PO 4/g-C3 N4/PVA复合膜的光腐蚀机理研究提供了重要的理论依据，并为Ag 3 PO 4/g-C3 N4/PVA复合膜在室内空气净化中的进一步应用提供了参考。
Ag3PO4semi-conductor has emerged out as an excellent photocatalyst in removing organic compounds. However, the photo-corrosion and stability of Ag3PO4limits its application. A series of Ag3PO4/g-C3N4/PVA composite films were prepared by facile ion-exchange and solvent blending method and utilized in degrading gaseous toluene under visible light in this study. Material characterization revealed that Ag3PO4particles were successfully deposited on the surface of g-C3N4. The results of gaseous toluene degradation showed that 2.6%-Ag3PO4/g-C3N4/PVA composites displayed the superior photo-catalytic performance among the as-prepared samples and the removal efficiency was about 1.35 and 1.26 times higher than that of g-C3N4/PVA and Ag3PO4/PVA, respectively. Additionally, discoloration of x%-Ag3PO4/g-C3N4/PVA composites was detected, and the mechanism of discoloration was discussed. Ag° was detected on the surface of composites, indicating that Ag+of Ag3PO4was reduced into Ag° by reacting with H2O molecules (known as photo-corrosion). The effect of PVA coating on as-prepared samples was significant in leading photo-corrosion as PVA absorbed H2O molecules to the surface of composites. However, PVA coating on the Ag3PO4was likely to form a chemically crosslinking network by ·OH produced on the surface of Ag3PO4, which further protected Ag3PO4from photo-corrosion. Humidity in the air played a major role in causing photo-corrosion of Ag3PO4and hence contributing to the sharp decrease of photocatalytic performance of composites. Moreover, compared to the system with a low humidity (6%), the stability of 2.6%-Ag3PO4/g-C3N4/PVA composite film in degrading gaseous toluene decreased sharply when the humidity was high (70%). This study provided a significant perspective in mechanism of photo-corrosion of Ag3PO4/g-C3N4/PVA composite films and might give some suggestions for further application of Ag3PO4/g-C3N4/PVA in purifying indoor air.