2021, Vol.31, No.2

Carbon Letters 2023 KCI Impact Factor : 1.35 KCI-WoS Impact Factor : 4.82

pISSN : 1976-4251 / eISSN : 2233-4998
https://journal.kci.go.kr/carbon

Compared to carbon nanotubes (CNTs), graphene possesses high strength due to wrinkled surface texture caused by a high density of surface defects which benefits more contact with the polymer material than a rolled-up CNT. In the present review, we have discussed and compared the various properties of CNTs (1-D) and graphene (2-D) obtained in experimental results. The effects of covalent and non-covalent functionalization of CNTs and graphene on the properties of its composites have also been reviewed and compared. A comparative analysis has been carried out between CNTs and graphene-reinforced polymer composites. Furthermore, the synergetic effects of CNTs and graphene hybrid nanofiller on the mechanical properties of polymer composites have also been briefly discussed. Finally, this review concludes with the potential application and future challenges are discussed with regards to filler and their polymer composites.

Recent years have witnessed remarkable development in the field of nanotechnology and it has been affirmed that carbon-based nanomaterials have wide applications in agriculture, industrial, biomedical and environmental sectors. Due to distinctive physicochemical properties of the carbon nanotubes (CNTs), they have been extensively utilized in plant science as a growth promoter, and thus, could be a boon for biomass production of agricultural products. Studies suggest that CNTs help increase the plant’s ability to absorb water and essential nutrients, thereby increasing growth. Apart from this, CNTs have been scrutinized for their utilization in genetic engineering for the delivery of genes, proteins or drugs. However, the literature discloses mixed effects of CNTs exposure on plants like in inducing oxidative stress by generating reactive oxygen species (ROS). Moreover, studies concerning CNTs interaction with plant system is at a nascent stage and needs further investigations to explore the mechanisms influencing the growth and toxicity in plants. Therefore, this review attempts to highlight the current literature on CNTs (including both single walled and multi walled) exposure on plants. It also explores unresolved challenges, as well as recommendations to ensure sustainable development of CNTs while minimizing any possible adverse health impacts.

Graphene, an allotrope of carbon in 2D structure, has revolutionised research, development and application in various disciplines since its successful isolation 16 years ago. The single layer of sp2-hybridised carbon atoms brings with it a string of unrivalled characteristics at a fraction of the price of its competitors, including platinum, gold and silver. More recently, there has been a growing trend in the application of graphene in catalysis, either as metal-free catalysts, composite catalysts or as catalyst supports. The unique and extraordinary properties of graphene have rendered it useful in increasing the reactivity and selectivity of some reactions. Owing to its large surface area, outstanding adsorptivity and high compatibility with various functional groups, graphene is able to provide a whole new level of possibilities and flexibilities to design and synthesise fit-for-purpose graphene-based catalysts for specific applications. This review is focussed on the progress, mechanisms and challenges of graphene application in four main reactions, i.e., oxygen reduction reaction, water splitting, water treatment and Fischer–Tropsch synthesis. This review also summarises the advantages and drawbacks of graphene over other commonly used catalysts. Given the inherent nature of graphene, coupled with its recent accelerated advancement in the synthesis and modification processes, it is anticipated that the application of graphene in catalysis will grow exponentially from its current stage of infancy.