g-C_(3)N_(4)/POPs异质结制备及其可见光催化性能

Preparation and visible light catalytic performance of g-C_(3)N_(4)/POPs heterojunction

光催化技术是一种极具应用前景的环境修复技术,开发高效、稳定、具有可见光响应的光催化剂是其研究的重点之一。本文采用常压溶剂热法,以1,3,5-三(4-氨基苯基)苯(TAPB)和2,5-二甲氧基苯-1,4二甲醛(DMTP)为单体合成的共轭多孔有机聚合物TAPB-DMTP POP为基底,原位负载不同比例的g-C_(3)N_(4),制备g-C_(3)N_(4)/POPs复合光催化剂。通过XRD、FTIR、BET、TGA、UV-Vis DRS、电流-时间(i-t)和EIS等测试方法表征了g-C_(3)N_(4)/POPs的化学结构与光学特性。在可见光条件下,选择Cr(Ⅵ)为模型污染物探究了不同gC_(3)N_(4)负载量的g-C_(3)N_(4)/POPs光催化还原效率,并对pH值、催化剂用量和底物浓度等影响因素进一步探究。结果表明:在pH=2条件下,g-C_(3)N_(4)/POP-2表现出了最佳的光催化还原性能,可见光光照下,30 min还原效率达到99.1%,Cr(Ⅵ)还原效率相对g-C_(3)N_(4)和TAPB-DMTP POP显著提高,其拟合一级动力学速率常数分别为纯g-C_(3)N_(4)和TAPB-DMTP POP的22.0倍和2.2倍。同时该材料5次循环后对Cr(Ⅵ)还原率仍然达到90%以上,具有优良的光催化稳定性。

As a promising environmental remediation technology,the development of efficient and stable photocatalysts with visible light response is one of the important studies in photocatalysis technology.In this work,g-C_(3)N_(4)/porous organic polymers(POPs)composite photocatalysts were prepared via atmospheric solvothermal method.Different ratios of g-C_(3)N_(4)were in-situ loaded on conjugated porous organic polymers TAPB-DMTP POP synthesized with 1,3,5-tris(4-aminophenyl)benzene(TAPB)and 2,5-dimethoxybenzene-1,4-diformaldehyde(DMTP)as monomers.The chemical structure and optical properties of g-C_(3)N_(4)/POPs materials were characterized by XRD,FTIR,BET,TGA,UV-Vis DRS,current-time(i-t)and EIS methods.Cr(Ⅵ)was selected as the model pollutant,the photocatalytic reduction activities of g-C_(3)N_(4)/POPs photocatalysts with different g-C_(3)N_(4)loading ratios were explored under visible light conditions,and the effects of pH value,catalyst dosage and substrate concentration were further investigated.The results shows that g-C_(3)N_(4)/POP-2 exhibits the best photocatalytic reduction performance at pH=2 with the reduction efficiency of 99.1%after 30 min of visible illumination.The reduction efficiency of Cr(Ⅵ)is significantly improved over g-C_(3)N_(4)/POP-2 compared with pure g-C_(3)N_(4)and TAPB-DMTP POP,and the fitted first-order kinetics rate are 22.0 times and 2.2 times that of g-C_(3)N_(4)and TAPB-DMTP POP,respectively.This composite also exhibits excellent photocatalytic stability as the Cr(Ⅵ)reduction rate reaches more than 90%after five cycles.