Pseudocapacitance‐Induced Synaptic Plasticity of Tribo‐Phototronic Effect Between Ionic Liquid and 2D MoS₂

Abstract

Contact‐induced electrification, commonly referred to as triboelectrification, is the subject of extensive investigation at liquid–solid interfaces due to its wide range of applications in electrochemistry, energy harvesting, and sensors. This study examines the triboelectric between an ionic liquid and 2D MoS2 under light illumination. Notably, when a liquid droplet slides across the MoS2 surface, an increase in the generated current and voltage is observed in the forward direction, while a decrease is observed in the reverse direction. This suggests a memory‐like tribo‐phototronic effect between ionic liquid and 2D MoS2. The underlying mechanism behind this tribo‐phototronic synaptic plasticity is proposed to be ion adsorption/desorption processes resulting from pseudocapacitive deionization/ionization at the liquid–MoS2 interface. This explanation is supported by the equivalent electrical circuit modeling, contact angle measurements, and electronic band diagrams. Furthermore, the influence of various factors such as velocity, step size, light wavelength and intensity, ion concentration, and bias voltage is thoroughly investigated. The artificial synaptic plasticity arising from this phenomenon exhibits significant synaptic features, including potentiation/inhibition, paired‐pulse facilitation/depression, and short‐term memory (STM) to long‐term memory (LTM) transition. This research opens up promising avenues for the development of synaptic memory systems and intelligent sensing applications based on liquid–solid interfaces.

Polarization‐Sensitive and Self‐Driven Pyro‐Phototronic Photodetectors Based on MoS2‐Water Heterojunctions

“…We have also previously reported that the water-MoS 2 device demonstrates a reflectance of ≈3.5% at the same wavelength. [36] Therefore, the absorption of water is minimal at this specific wavelength. MoS 2 on its own is not a polarization-sensitive material due to its isotropic structure.…”

“…Although MoS 2 is typically an n-type semiconductor, the IV characteristics and band bending of MoS 2 -water heterojunction are similar to those of p-type silicon-water probably due to the low electron concentration of MoS 2 . [36] Upon white light illumination (solar spectrum, AM1.5G) at an intensity of 100 mW cm −2 , the concentration of photogenerated carriers in the MoS 2 increases, leading to an increase in the photogenerated current density of the MoS 2 -water device and an open circuit voltage of ≈0.52 V, demonstrating the photovoltaic effect [37] (Figure 1e). To study the pyroelectric behavior of the MoS 2 -water junction, a series of heat pulses at temperatures of ≈40, 60, 80, and 100 °C were applied to the backside of the MoS 2 -water device (Figure 1f).…”

Contact-electro-catalysis under natural and industrial conditions: mechanisms, strategies, and challenges

“…As solid-liquid contact electrication (S-L CE) is the rst step of CEC, the discussion of CE is the direct way to rst reveal the mechanism of CEC. S-L CE includes S-L electron transfer and S-L ion transfer, 21,22 where the former is the process of producing electron-hole pairs to generate ROS through the mass transfer process of electrons in the CEC reaction, 23 whereas the latter has a weak contribution to CEC performance. 24 Under natural or industrial conditions, the water composition is complicated.…”