Preparation Of Carbon Nanosheets Research Articles

Preparation of carbon nanosheets from petroleum asphalt via recyclable molten-salt method for superior lithium and sodium storage

Carbon nanosheets were successfully prepared from easily available and low-cost petroleum asphalt via a facile and recyclable molten-salt method. The as-made carbon nanosheets exhibit excellent performance on energy storage both for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs): as the anode of LIBs, they provide a high reversible specific capacity (729 mAh g−1 at 100 mA g−1), excellent cyclability (600 mAh g−1 at 1 A g−1 after 500 cycles), and improved rate performance (280 mAh g−1 at 5 A g−1). For SIBs, they also display a reversible capacity of 300 mAh g−1 at 50 mA g−1, remarkable rate capability (90 mAh g−1 at 5 A g−1) and retain as high as 95 mAh g−1 after 10000 cycles at 2 A g−1. The superior electrochemical performance of carbon nanosheets could be attributed to their peculiar structural characteristics that integrate a variety of advantages: fast electronic and ionic conductivity, easy penetration of the electrolyte, shortened path for Li+/Na+ migration and structural stability. This approach paves the way for industrial scale-up due to its eco-friendliness, simplicity and versatility.

Preparation of Carbon Nanosheets at Room Temperature.

Amphiphilic molecules equipped with a reactive, carbon-rich "oligoyne" segment consisting of conjugated carbon-carbon triple bonds self-assemble into defined aggregates in aqueous media and at the air-water interface. In the aggregated state, the oligoynes can then be carbonized under mild conditions while preserving the morphology and the embedded chemical functionalization. This novel approach provides direct access to functionalized carbon nanomaterials. In this article, we present a synthetic approach that allows us to prepare hexayne carboxylate amphiphiles as carbon-rich siblings of typical fatty acid esters through a series of repeated bromination and Negishi-type cross-coupling reactions. The obtained compounds are designed to self-assemble into monolayers at the air-water interface, and we show how this can be achieved in a Langmuir trough. Thus, compression of the molecules at the air-water interface triggers the film formation and leads to a densely packed layer of the molecules. The complete carbonization of the films at the air-water interface is then accomplished by cross-linking of the hexayne layer at room temperature, using UV irradiation as a mild external stimulus. The changes in the layer during this process can be monitored with the help of infrared reflection-absorption spectroscopy and Brewster angle microscopy. Moreover, a transfer of the carbonized films onto solid substrates by the Langmuir-Blodgett technique has enabled us to prove that they were carbon nanosheets with lateral dimensions on the order of centimeters.

Preparation of Carbon Nanosheets at Room Temperature

Preparation of Carbon Nanosheets at Room Temperature