Surikanti Ganesh Reddy, Bajaj Pooja, Sunkara Manorama V
Nanomaterials Laboratory, Department of Polymers and Functional Materials, CSIR-Indian Institute of Chemical Technology, Uppal Road, Tarnaka, Hyderabad 500 007, India.
Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India.
ACS Omega. 2019 Oct 7;4(17):17301-17316. doi: 10.1021/acsomega.9b02031. eCollection 2019 Oct 22.
A highly porous architecture of graphitic carbon nitride g-CN/CuO nanocomposite in the form of cubes with a side length of ≈ 1 μm, large pores of 1.5 nm, and a high surface area of 9.12 m/g was realized by an optimized in situ synthesis protocol. The synthesis protocol involves dispersing a suitable "Cu" precursor into a highly exfoliated g-CN suspension and initiating the reaction for the formation of CuO. Systematic optimization of the conditions and compositions resulted in a highly crystalline g-CN/CuO composite. In the absence of g-CN, the CuO particles assemble into cubes with a size of around 300 nm and are devoid of pores. Detailed structural and morphological evaluations by powder X-ray diffraction and field emission scanning electron microscopy revealed the presence of highly exfoliated g-CN, which is responsible for the formation of the porous architecture in the cube like assembly of the composite. The micrographs clearly reveal the porous structure of the composite that retains the cubic shape of CuO, and the energy-dispersive spectroscopy supports the presence of g-CN within the cubic morphology. Among the different g-CN/CuO compositions, CN/Cu-5 with 10% of g-CN, which is also the optimum composition resulting in a porous cubic morphology, shows the best visible light photocatalytic performance. This has been supported by the ultraviolet diffuse reflectance spectroscopy (UV-DRS) studies of the composite which shows a band gap of around 2.05 eV. The improved photocatalytic performance of the composite could be attributed to the highly porous morphology along with the suitable optical band gap in the visible region of the solar spectrum. The optimized composite, CN/Cu-5, demonstrates a visible light degradation of 81% for Methylene Blue (MB) and 85.3% for Rhodamine-B (RhB) in 120 min. The decrease in the catalyst performance even after three repeated cycles is less than 5% for both MB and RhB dyes. The rate constant for MB and RhB degradation is six and eight times higher with CN/Cu-5 when compared with the pure CuO catalyst. To validate our claim that the dye degradation is not merely decolorization, liquid chromatography-mass spectroscopy studies were carried out, and the end products of the degraded dyes were identified.
通过优化的原位合成方案，实现了边长约为1μm的立方体形石墨相氮化碳g-CN/CuO纳米复合材料的高度多孔结构，其具有1.5nm的大孔和9.12m²/g的高比表面积。该合成方案包括将合适的“Cu”前驱体分散到高度剥离的g-CN悬浮液中，并引发形成CuO的反应。对条件和组成进行系统优化，得到了高度结晶的g-CN/CuO复合材料。在没有g-CN的情况下，CuO颗粒聚集成尺寸约为300nm的立方体且无孔隙。通过粉末X射线衍射和场发射扫描电子显微镜进行的详细结构和形态评估表明存在高度剥离的g-CN，这是复合材料立方体状组装中多孔结构形成的原因。显微照片清楚地揭示了保留CuO立方形状的复合材料的多孔结构，能量色散光谱证实了立方形态内存在g-CN。在不同的g-CN/CuO组成中，含有10% g-CN的CN/Cu-5（也是产生多孔立方形态的最佳组成）表现出最佳的可见光光催化性能。这得到了复合材料的紫外漫反射光谱（UV-DRS）研究的支持，该研究表明带隙约为2.05eV。复合材料光催化性能的提高可归因于高度多孔的形态以及太阳光谱可见光区域中合适的光学带隙。优化后的复合材料CN/Cu-5在120分钟内对亚甲基蓝（MB）的可见光降解率为81%，对罗丹明B（RhB）的可见光降解率为85.3%。对于MB和RhB染料，即使经过三个重复循环，催化剂性能的下降也小于5%。与纯CuO催化剂相比，CN/Cu-5对MB和RhB降解的速率常数分别高出六倍和八倍。为了验证我们关于染料降解不仅仅是脱色的说法，进行了液相色谱-质谱研究，并确定了降解染料的最终产物。
