Periodic Reporting for period 5 - MATTERDESIGN (New Science and Technology of Artificial Layered Structures and Devices)
Periodo di rendicontazione: 2021-01-01 al 2022-04-30
One billion people across the globe currently lack regular access to safe drinking water and more than half of the world’s population may be facing a water crisis by 2050. One solution is to produce fresh water from our oceans (which cover more than 70% of the Earth’s surface) by removing the dissolved salt, a process known as desalination. However, exorbitant operational costs and daunting environmental challenges, such as safe disposal of the waste produced, leave ocean desalination a futile option. Keeping this in mind, in this project, we investigated water, ions, and other molecular transport properties of extremely narrow 2D capillaries fabricated by assembling various 2D crystals. The potential applications of 2D nano capillaries for water desalination, solvent filtration, and micro and ultrafiltration were primarily investigated in this project. Furthermore, the potential of these 2D channels for the synthesis of novel two-dimensional materials and their applications in designing novel superconductors were investigated.
We obtained several groundbreaking research results during the project. First, we developed a new form of graphene oxide membrane that can filter organic solvents without compromising its ability to sieve out the smallest of particles. Previously graphene-oxide membranes were shown to be completely impermeable to all solvents except for water. Out studies changed that perception and allowed for expansion in the applications of graphene-based membranes from water filtration to organic solvent nanofiltration (OSN). Second, we achieved a long-sought-after objective of electrically controlling water flow through membranes. Our research demonstrates precise control of water flow through graphene oxide membrane by using an electrical current. This research opens up an avenue for developing smart membrane technologies and has the potential to revolutionise the field of artificial biological systems, tissue engineering and filtration. Third, we made a leap forward in overcoming one of the biggest problems in membrane technology- membrane fouling. Fouling is an inevitable event in membrane separation, where blockages occur in the pores of a membrane, stopping the flow and preventing the membrane from functioning normally. Fouling is an especially severe issue for oil separation technology due to how easily the oil droplets stick onto the membrane surface. We demonstrated that the exfoliated two-dimensional form of vermiculite, a natural clay mineral, can be used as a fouling-resistant coating for oil-water separation. Fourth, we developed a new method to synthesize 2D materials that are thought to be impossible or, at least, unobtainable by current technologies. By using chemical conversion, we were able to convert layers of existing layered materials into a new covalent two-dimensional material. As an example, mechanically exfoliated 2D indium selenide (InSe) is converted into atomically thin indium fluoride (InF3), which has a non-layered structure and therefore cannot possibly be obtained by exfoliation, by a fluorination process. Our work provides a significant advance in materials science and is a clear milestone in the development of artificial 2D materials. We have also found a novel method to create 2D palladium sheets by a self-limiting growth of palladium inside graphene oxide nano capillaries. Fifth, we developed a novel yet simple method for producing vertical stacks of alternating superconductor and insulator layers of tantalum disulphide (TaS2). Our work describes the synthesis of a bulk van der Waals heterostructure consisting of alternating atomic layers of 1T and 1H TaS2. 1T and 1H TaS2 are different polymorphs (materials with the same chemical composition but with a variation in atomic arrangement) of TaS2 with completely different properties – the former insulating, the latter superconducting at low temperatures.
All the research output from this project advances the research field significantly beyond state-of-the-art. For example, the organic solvent permeation and filtration properties of the developed membranes clearly outperformed the state-of-the-art polymeric and ceramic membranes in terms of permeance and rejections of organic solvent and solute, respectively. Electrical control of water permeation is the first experimental report on this topic. Similarly, the antifouling performance of vermiculite coating was compared with state-of-the-art polymeric membranes and demonstrated its superior performance. The findings from this project were published in high-impact publications and presented at various scientific conferences as invited or keynote talks. The scientific impact of our work can be seen in the rapidly growing citations of the published papers. The PI has received several prestigious awards and prizes for his research that acknowledge the work done within the project.