Researchers Eliminate Silicon Contamination of Graphene to Double Its Performance

( Nanowerk News ) New research reveals why graphene has not turned the electronics as promised and shows how to double its performance and finally exploit its extraordinary potential. Graphene is the most resistant material ever tested. It is also flexible, transparent and conducts heat and electricity 10 times better than copper. After receiving the Nobel Prize in Physics in 2010, graphene research has been hailed as a transformation material for flexible electronics, computer chips and more powerful solar panels, water filters and bio -capteurs. But performance has been mixed and adoption by the industry has been slow. Now, a study published in Nature Communications ("Silicon as a ubiquitous contaminant in graphene derivatives having a significant impact on device performance") identifies silicon contamination as being at the origin of the disappointing results and explains in detail how to produce efficient, pure graphene. The RMIT University team led by Drs. Dorna Esrafilzadeh and Rouhollah Ali Jalili inspected commercial atom-by-atom samples of graphene using a scanning electron microscope at the cutting-edge technology. "We found high levels of silicon contamination in commercially available graphene, with considerable impacts on the performance of the material," said Esrafilzadeh. The tests showed that the silicon present in natural graphite, the raw material used to make graphene, was not completely eliminated during the treatment. "We believe this contamination is at the heart of many seemingly inconsistent reports on the properties of graphene and perhaps many other two-dimensional (2D) atomically thin materials," Esrafilzadeh said. "Graphene was supposed to be transformative, but it has not yet had a significant commercial impact, like similar 2D nanomaterials, and we now know why it did not deliver the expected results. 'we must do to exploit its full potential.' The tests not only allowed to identify these impurities, but also to demonstrate their major influence on performance, contaminated materials having a performance worse than 50% when tested as electrodes. "This level of inconsistency may have prevented the emergence of major industry applications for graphene-based systems, but it also prevents the development of regulatory frameworks for the implementation of these systems. layered nanomaterials, destined to become the hub of the future generation devices, "she said. The two-dimensional property of the graphene sheet, which is only one atom thick, is ideal for storing electricity and new sensor technologies based on a large area. This study reveals how this 2D property is also the Achilles heel of graphene, making it so vulnerable to surface contamination, and highlights the importance of high purity graphite for the production of graphene more pure. Using pure graphene, the researchers demonstrated how the material worked extraordinarily well when it was used to build a supercapacitor, a kind of super battery. During testing, the ability of the device to withstand electrical charges was enormous. In fact, it was the largest capacity so far recorded for graphene and in view of the predicted theoretical capacity of the material. In collaboration with RMIT's Advanced Materials and Industrial Chemistry Research Center, the team then used pure graphene to create a versatile moisture sensor with the greatest sensitivity and the most low limit of detection never reported. These results are an essential step for the full understanding of atomically thin two-dimensional materials and their successful integration into high-performance commercial devices.
"We hope this research will help unlock the exciting potential of these materials."