GO增强g-C_(3)N_(4)气凝胶的可见光响应及其光催化降解偏二甲肼废水

GO enhanced visible-light response of g-CN aerogel and degradation of unsymmetrical dimethylhydrazine in wastewater

以超声剥离、溶液交联和冷冻干燥的方法制得系列GO/g-C_(3)N_(4)气凝胶材料,优化配比参数,通过SEM,XRD,UV-vis吸收光谱等表征材料物化性能,以光催化降解偏二甲肼(UDMH)废水评估材料的光催化活性。纯g-C_(3)N_(4)气凝胶以介孔结构为主,随着氧化石墨烯(GO)配比的提高,材料的层状结构、大孔结构逐渐增加,均表现出了较强的吸附性能;GO的质量分数为25%时光催化降解UDMH废水效果最佳、性能稳定,5次循环后,光催化活性仅降低了7.15%。通过能带结构、光电效应及PL谱表征,研究发现g-C_(3)N_(4)分子轨道能级和带隙(Eg)因受GO层间π-π键与g-C_(3)N_(4)芳香环的交联作用影响,而提高了对可见光的响应性能;GO的金属特性有利于光生电子空穴对的快速分离,进而提高光催化活性;根据带隙计算及材料本征分子轨道特性,GOCN光催化降解UDMH废水的主要活性物质为·O^(-)_(2),h^(+)。

A series of GO/g-C_(3)N_(4) aerogel materials were prepared by the methods of ultrasonic peeling, solution cross-linking and freeze-drying, and the proportion of raw materials were optimized. The materials were characterized by SEM,XRD,and UV-vis absorption spectrum. The photocatalytic activity was evaluated by the degradation of unsymmetrical dimethylhydrazine(UDMH) wastewater. The pure g-C_(3)N_(4) aerogel was dominated by mesoporous structure. As the graphene oxide(GO) ratio increases, the layered structure and macroporous structure of the material gradually increase, and all show strong adsorption performance. When the mass fraction of GO is 25%, the photocatalytic degradation of UDMH wastewater is the best and the performance is stable after 5 cycles, the photocatalytic activity is only reduced by 7.15%. Through the study on the energy band structure, characterization of photoelectric effect and PL spectrum, the results show that the g-C_(3)N_(4) molecular orbital energy level and band gap(Eg) were impacted by the cross-linking between the π-π bond of GO layers and the aromatic ring of g-C_(3)N_(4), which improve the response performance to visible light. The metallic properties of GO facilitate the rapid separation of photogenerated electron-hole pairs and improve the photocatalytic activity. According to the band gap calculation and the intrinsic molecular orbital of the material, the main active species for GOCN photocatalytic degradation of UDMH wastewater are ·O^(-)_(2) and h_(+).