g-C3N4/泡沫镍整体式光催化剂的构建及光氧化去除NO

Construction of g-C3N4/Ni-foam Monolithic Photocatalyst and Removal of NO by Photo-oxidation

本工作以泡沫金属(M-foam,M=Ni、Cu、Fe)为载体,采用浸渍法制备了g-C3N4/泡沫金属整体式光催化剂,并分别对三种整体式光催化剂的负载牢固性和光催化活性进行了系统研究,得出泡沫镍为构建整体式光催化剂的最佳载体。对比g-C3N4/泡沫镍与粉体g-C3N4的光催化活性发现,g-C3N4/泡沫镍的一氧化氮(NO)去除率为粉体g-C3N4的1.8倍,表明泡沫镍的引入能明显增强g-C3N4的光催化活性。同时,对g-C3N4/泡沫镍的结构形貌、光学性质以及反应活性物种进行分析,将g-C3N4/泡沫镍光催化活性增强的因素主要归于以下两点:一是泡沫镍的多孔结构提高了g-C3N4的分散度,因而暴露出更多的光催化反应活性位点,从而增强了NO在g-C3N4表面的吸附,提高了反应效率;二是泡沫镍良好的导电性有助于g-C3N4表面电子的转移,从而提高了光生电子-空穴的分离效率。此外,g-C3N4/泡沫镍在光照条件下产生的超氧自由基(·O2^-)和羟基自由基(·OH)是光氧化NO生成NO3-的主要反应活性物种。本研究为粉体光催化剂的性能提升和实际应用提供了一种新思路。

In this work,g-C3N4 /M-foam monolithic photocatalyst was prepared via an impregnation method,which metal foam ( M-foam,M=Ni,Cu and Fe) works as supporter. Three different monolithic photocatalysts have been studied systematically for the load stability as well as photocatalytic performance,which revealed that Ni-foam is the best candidate for monolithic photocatalyst formation. The g-C3N4 /Ni-foam monolithic photocatalysts exhibited a 1.8 times higher NO removal ratio than powder g-C3N4 ,indicating the improvement of photocatalytic performance after introduction of Ni-foam. Moreover,by studying the structure,morphology,optical properties and reactive species of g-C3N4 /Ni-foam,it is found that the enhancement of photocatalytic performance of g-C3N4 /Ni-foam is mainly attributed to the following two reasons: Firstly,the porous structure of Ni-foam can enlarge the dispersibility and provide more active sites for photocatalytic reaction,enhancing the adsorption capacity and photodegradation efficiency of NO on the surface of g-C3N4;Secondly,the Ni-foam exhibited excellent electron transfer property which can strictly restrict the recombination efficiency of electron-hole pairs. Notably,in this system,superoxide radicals (·O2^-) and hydroxyl radicals (·OH) were considered to be the main active species for photo-oxidation of NO to NO3 -under illumination over g-C3N4 /Ni-foam. This work provide a fresh insight for highly efficient performance and practical application of powder photocatalyst.