二维g-C_(3)N_(4)与Ag-TiO_(2)复合光催化剂降解气态乙醛抗失活研究

Two-dimensional g-C_(3)N_(4) Compositing with Ag-TiO_(2) as Deactivation Resistant Photocatalyst for Degradation of Gaseous Acetaldehyde

光催化剂失活是影响其在去除低浓度VOCs的实际应用中的主要因素之一。本研究将TiO_(2)与2D石墨碳氮化碳(g-C_(3)N_(4))复合,显著提高了光催化剂的稳定性。当Ag改性的Ag-TiO_(2)(AT)用于降解乙醛气体时,反应60 min后开始发生失活现象,反应延长至400 min则完全失活。而AT与g-C_(3)N_(4)复合改性后的样品g-C_(3)N_(4)/Ag-TiO_(2)(CAT)具有优异的光催化性能和稳定性,反应至600 min未发生失活。原位FT-IR、PL和光电流的研究表明,当AT催化降解乙醛时,反应中间体会在表面积累导致催化剂失活。而引入的g-C_(3)N_(4)可以为中间体提供更多的吸附位点,从而提高稳定性。此外,引入g-C_(3)N_(4)还有利于电荷分离和产生活性氧物种,促进乙醛和中间体降解。本研究揭示了2D材料在开发稳定可持续降解VOCs的光催化剂方面的实用性。

The photocatalysts deactivation is one of the major issues,which lowers the usefulness of photocatalytic oxidation technology for the removal of low content volatile organic compounds(VOCs).Here,we carried out a series of experiments to demonstrate that the photocatalysts stability could be significantly improved via coupling the oxide base semiconductors,i.e.,TiO_(2) with 2D materials such as graphitic carbon nitride(g-C_(3)N_(4)).Initially,when Ag modified TiO_(2)(AT)was used for the gaseous acetaldehyde degradation,a robust deactivation was observed within 60 min.The AT catalyst completely lost its activity when the reaction time was extended to 400 min.On the contrary,the g-C_(3)N_(4) modified AT(CAT)showed superior photocatalytic performance and improved stability(600 min).The in-situ FT-IR,PL,and photocurrent studies suggested that the accumulation of reaction intermediates in the case of AT fundamentally caused the deactivation.However,the g-C_(3)N_(4) provided excessive adsorption sites for the reaction by-products which improved the stability.Additionally,the PL and ESR studies suggested that the existence of g-C_(3)N_(4) improved the charge separation and production of reactive oxygen species,which facilitated the photodegradation of acetaldehyde and ultimate reaction products.This study realizes the usefulness of 2D materials for developing stable and visible light active photocatalysts for applications in sustainable VOC abatement technology.