Using Thermoelectric MoS2-Based Thin Films for Novel Desalination and Battery Technologies via Selective Ion Transport

Molybdenum disulfide (MoS₂) is a widely studied transition metal dichalcogenide with a range of potential applications including next-generation electronics, hydrogen evolution, and catalysis. It can also be used as a thermoelectric, exploiting the Seebeck effect to generate an electric voltage in response to a temperature gradient. Additionally, lithium-intercalated MoS₂ is known to undergo a transition from the 2H to 1T phase. Each of these phases has characteristic physical properties such as hydrophobicity and net surface charge that mediate interactions with aqueous salt solutions for selective ion uptake. The combination of these features makes this material suitable as a novel desalination technology that relies on ion movement powered by a thermoelectric potential. Furthermore, this ionic transport can be harnessed to recharge a thermoelectric battery in response to environmental temperature variations.<br/><br/>To assess MoS₂’s capabilities for ion transport, three types of experiments were conducted. The first set of experiments investigated changes in electric potential resulting from dropwise contact of various salt solutions with an MoS₂membrane. Droplet test data displayed abrupt changes in electric potential followed by an exponential decay representing ion/carrier movement with respect to time. A second set of experiments measured ion concentration changes over time using an MoS2 film in contact with a temperature gradient and separated DI water and salt solutions. Significant changes in solution ion osmolarities were recorded after a duration of one week. Finally, voltages were measured across these films to better understand ionic flow in response to temperature variations. Ongoing research is investigating ionic transport in combined MoS₂/Aquivion structures for future use in batteries. Results are promising for future development of thermoelectric desalination devices as well as new energy storage and medical technologies.