Under a high-powered microscope, MXenes resemble a cross-section of a flaky pastry. This two-dimensional layered structure gives them remarkable properties; MXenes are strong, flexible and stable and make excellent superconductors of heat and electricity.
The sky’s the limit for these man-made materials, with utility in sectors spanning energy storage, water desalination, medicine and many more. According to materials scientists, however, MXenes lack sufficient research to fully understand their properties since their discovery about a decade ago.
"To fully unlock the potential of MXenes for industrial-scale adoption, it is crucial to critically evaluate current synthesis methods and explore new approaches to produce the materials with higher quality and yields," said Zhi Wei Seh, a Senior Scientist at A*STAR's Institute of Materials Research and Engineering (IMRE).
Seh teamed up with researchers from Harvard University, Drexel University and Indiana University-Purdue University Indianapolis to assemble the first how-to guide for advanced MXene synthesis.
"We hoped to provide fellow researchers with the best practices for preparation, characterisation and testing of MXenes," explained the first author of the study, Garrick Lim, adding that these much-needed frameworks can plant the seeds for future innovations in the field.
The researchers collected and analysed computational modelling data from MXene research efforts as well as outputs from material characterisation studies at every stage of the MXene synthesis workflow.
"We re-examined the entire MXene production process including the preparation of precursor materials, the etching of intermediates into multi-layered MXenes and the delamination of layers into individual 2D sheets," said Lim.
They found that many factors influenced the end product—how MXene precursors were prepared, their ratios in the MXene ‘recipe’ and heating conditions all came into play. Among these, the choice of intercalants for creating MXenes’ signature layered sheets was deemed essential for fine-tuning the material’s properties to suit a given application.
Kickstarting the MXene industry would not be possible without such thorough and systematic approaches to understanding the intricacies of MXene synthesis, said Lim, adding that it also sparks the possibility of creating unique, highly specialised variants in the future.
Speaking on one such technique for synthesising MXenes under blazing heat, Lim said, "Such extreme conditions can result in the formation of unique surface functional groups that lead to anomalous magnetic properties for use in spintronics applications."
The research team led by Seh is currently working on incorporating highly conductive MXenes into batteries and electrocatalysts towards the development of next-generation sustainable energy solutions.
The A*STAR-affiliated researchers contributing to this research are from the Institute of Materials Research and Engineering (IMRE).