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首页> 外文期刊>Current Graphene Science >Reduced Graphene Oxides (rGOs) using Nature-based Reducing Sources: Detailed Studies on Properties, Morphologies and Catalytic Activity | Bentham Science
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Reduced Graphene Oxides (rGOs) using Nature-based Reducing Sources: Detailed Studies on Properties, Morphologies and Catalytic Activity | Bentham Science

机译：使用基于自然的还原源还原石墨烯氧化物（rGOs）：关于性质，形态和催化活性的详细研究边沁科学

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Background: Reduced graphene oxide (rGO) is often prepared from graphene oxide (GO) byusing various reducing agents like hydrazine hydrate, dimethylhydrazine, sodium borohydride, hydroquinoneetc. In view of the toxicity of chemical reagents, recent trends are directed towards the use of naturederivedbiomolecules as the reducing source. The present study describes a comparative evaluation ofdifferent properties of reduced graphene oxides (rGOs), prepared by using chemical and biological reducingsources, and investigated their catalytic functions in the reduction of nitrobenzene to aniline.Methods: GO is prepared from graphite powder following modified Hummers oxidation and subsequentexfoliation by sonication. In order to obtain rGO, four different plants leaf extracts viz. AdathodaVasika (Malabar nut), Azadirachta Indica (Neem), Camellia Sinensis (Tea), Moringa Oleifera (Drumstick),and a fungi extract of Volvereilla Volvacea (Mushroom) are chosen primarily from the local sub-Himalayan region, all are edible to human beings as well as have long been used as traditional medicinesto combat with various diseases. The plant leaves are washed carefully with distilled water, keptin air oven at 80 oC for two days, and then the dry leaves are crushed to fine powder. The plant leafextractsare obtained by stirring a suspension of each type of finely grinded leaf powder (500 mg in 80mL of DI water) overnight at room temperature and filtering the extract to remove any dust plantleaves. Each rGO is denoted as rGO-AV, rGO-AI, rGO-CS, rGO-MO and rGO-VV, based on theabbreviation of sources. The rGO-HH stands for rGO obtained by using hydrazine hydrate.Results: Each rGO was characterized by UV-Vis, FT-IR, Raman spectroscopic techniques, and surfacemorphological aspects were studied by powder XRD, Scanning and Transmission electron microscopicimages (SEM and TEM). The acidic nature (pH) of each rGO in aqueous suspension as well as cationexchangecapacity was measured by potentiometric titration in the absence and presence of an electrolyterespectively. Finally, the catalytic ability was evaluated in the reduction of nitrobenzene to anilineat room temperature monitored by UV-Vis spectrophotometer. While textural aspects of various rGOsare fairly similar, various physicochemical properties like pH, cation-exchange ability etc are found tobe different for rGOs obtained by using different phyto-extracts. Moreover, there is significant variationobserved in their catalytic activity in the reduction of nitrobenzene.Conclusion: Present studies establish that the rGO can be efficiently prepared by various naturederivedaqueous extracts. Although the textural aspects of rGOs display marginal changes, their catalyticactivity in the reduction of nitrobenzene to aniline greatly differs, as studied by UV-Vis spectrophotometrickinetic measurements. By comparison, it is found that rGOs obtained by using plant leafextract of Adathoda Vasika, (rGO-AV) and an edible mushroom extract of Volvereilla Volvacea, (rGOVV)exhibit significantly better catalytic efficiency than others.
机译：背景：还原氧化石墨烯（rGO）通常是通过使用各种还原剂（例如水合肼，二甲基肼，硼氢化钠，氢醌等）从氧化石墨烯（GO）制备的。考虑到化学试剂的毒性，最近的趋势是针对使用天然来源的生物分子作为还原源。本研究描述了使用化学和生物还原源制备的还原石墨烯氧化物（rGOs）不同性能的比较评估，并研究了它们在将硝基苯还原为苯胺中的催化作用。以及随后通过超声去除角质。为了获得rGO，四种不同的植物叶片提取物即。 AdathodaVasika（马拉巴尔坚果），Azadirachta Indica（印度em），Camellia Sinensis（茶），Moringa Oleifera（小鸡腿）和Volvereilla Volvacea（蘑菇）的真菌提取物均主要选自喜马拉雅地区。生物以及长期以来一直用作抗击各种疾病的传统药物。用蒸馏水仔细清洗植物叶片，将其在80 oC的空气烘箱中保存两天，然后将干燥的叶片粉碎成细粉。通过在室温下将每种细磨的叶粉（在80mL的去离子水中的500 mg）的悬浮液搅拌过夜，然后过滤提取液以除去任何灰尘的植物叶子，从而获得植物叶提取物。根据来源的缩写，每个rGO分别表示为rGO-AV，rGO-AI，rGO-CS，rGO-MO和rGO-VV。结果：rGO-HH代表通过水合肼获得的rGO。结果：每个rGO均通过UV-Vis，FT-IR，拉曼光谱技术表征，并通过粉末XRD，扫描和透射电子显微镜图像（SEM和TEM）研究表面形态）。通过在不存在和存在电解质的情况下通过电位滴定法分别测量水性悬浮液中每个rGO的酸性（pH）和阳离子交换能力。最后，在室温下通过紫外可见分光光度计监测硝基苯还原成苯胺的催化能力。尽管各种rGO的质地方面相当相似，但发现通过使用不同的植物提取物获得的rGO的各种理化性质（如pH，阳离子交换能力等）是不同的。此外，在硝基苯的还原反应中，它们的催化活性存在显着变化。结论：目前的研究表明，rGO可以通过各种自然来源的水提取物有效制备。尽管rGOs的质地方面显示出很小的变化，但如通过UV-Vis分光光度动力学测量法所研究，它们在将硝基苯还原为苯胺方面的催化活性差异很大。相比之下，发现通过使用Adathoda Vasika的植物叶提取物（rGO-AV）和Volvereilla Volvacea的可食用蘑菇提取物（rGOVV）获得的rGOs表现出明显优于其他植物的催化效率。

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