Photothermoelectric Response of Ti₃C₂T_x MXene Confined Ion Channels

Abstract

With recent growing interest in biomimetic smart nanochannels, a biological sensory transduction in response to external stimuli has been of particular interest in the development of biomimetic nanofluidic systems. Here we demonstrate the MXene-based subnanometer ion channels that convert external temperature changes to electric signals via preferential diffusion of cations under a thermal gradient. In particular, coupled with a photothermal conversion feature of MXenes, an array of the nanoconfined Ti 3 C 2 T x ion channels can capture trans-nanochannel diffusion potentials under a light-driven axial temperature gradient. The nonisothermal open-circuit potential across channels is enhanced with increasing cationic permselectivity of confined channels, associated with the ionic concentration or pH of permeant fluids. The photothermoelectric ionic response (evaluated from the ionic Seebeck coefficient) reached up to 1 mV·K –1 , which is comparable to biological thermosensory channels, and demonstrated stability and reproducibility in the absence and presence of an ionic concentration gradient. With advantages of physicochemical tunability and easy fabrication process, the lamellar ion conductors may be an important nanofluidic thermosensation platform possibly for biomimetic sensory systems.

Recent Progress in Emerging Two-Dimensional Transition Metal Carbides

“…Hong et al reported the sub-nano ion channel based on 2D-TMCs, which can convert external temperature changes into electrical signals through the preferential diffusion of cations under a thermal gradient. Based on the photothermal conversion of MXenes, the Ti 3 C 2 T x ion channel can capture the diffusion potential across the nanochannel under the axial temperature gradient of the light drive and exhibit the photothermoelectric ionic response of 1 mV K -1 [215].…”

Light-Driven Ion Transport in Nanofluidic Devices: Photochemical, Photoelectric, and Photothermal Effects

“…56 Hong et al reported that an array of nanoconfined Ti 3 C 2 T x ion channels could capture transnanochannel diffusion potentials under a light-driven axial temperature gradient. 37 The thermoelectric Page 8 of 25 CCS Chemistry response of MXene nanofluidics was calculated to reach up to 1.0 mV•K −1 under local sunlight exposure (Fig. 4a).…”

“…To date, three different mechanisms, including photochemical, 35,36 photoelectrical, 8,22 and photothermal effects, 37,38 have been proposed to explain the light-driven ion transport phenomenon (Fig. 1).…”

Bioinspired nanochannels based on polymeric membranes

“…Salinity gradient energy, the Gibbs free energy [204] in the salt solutions of varying concentrations, is known as the blue energy and can be converted into electrical energy by reverse electrodialysis (RED) [205,206]. Considering the great potential of marine resources, the salinity gradient has great potential in alleviating the energy crisis in the future.…”