Na‐Cation‐Assisted Exfoliation of MX₂ (M = Mo, W; X = S, Se) Nanosheets in an Aqueous Medium with the Aid of a Polymeric Surfactant for Flexible Polymer‐Nanocomposite Memory Applications

Abstract

2D nanosheets of transition metal dichalcogenides (TMDCs) have been attracting attention due to their sizable band gap. Facile and effective Na-cation-assisted exfoliation of TMDC (MX , M = Mo, W; X = S, Se) nanosheets in an aqueous medium and their application as a composite filler in a polyvinyl alcohol (PVA) matrix are explored in this work. The presence of Na cations is highly beneficial for exfoliating defect-free and few-layer MX nanosheets in water in the presence of small-sized micelles of polymeric surfactant, and significantly elevates the exfoliation yield by more than one order of magnitude compared to a conventional surfactant-assisted exfoliation. The strategy suggested in this work is very advantageous compared to both Li cation intercalation in organic solvents and conventional low-yield surfactant-assisted exfoliations. As an application of the exfoliated nanosheets, the fabrication of memory devices with the configuration of Ga-doped ZnO/MX -PVA/Ag is demonstrated, and they exhibit bistable and write-once-read-many-times resistive switching behavior with a high ON/OFF current ratio of 3 × 10 at -1.0 V (for WS ) and 2.0 V (for MoS ). Furthermore, MX -PVA nanocomposite fibrous films and mats are successfully fabricated using an electrospinning technique, which can expand the use of TMDC nanofillers in applications involving highly flexible polymer-based MX composites.

Recent advances in organic‐based materials for resistive memory applications

“…Polymer‐based materials are another class of promising contenders for the development of novel resistive memory devices 17,43,44,49,74,108,111‐129 . Polymer functional materials possess similar advantages to organic small molecules, such as low cost, good flexibility, and ease of processing, which can serve as alternatives or supplements to their inorganic counterparts 43,111‐120 .…”

“…It should be noted that polymers could also serve as matrixes for metallic NPs or other inorganic compounds for memory operations 49,126‐129 . Zhang et al prepared uniform charge‐trapping Co 9 Se 8 quantum dots (CSQDs) and blended them with polyvinylpyrrolidone (PVP).…”

Overview of Resistive Random Access Memory (RRAM): Materials, Filament Mechanisms, Performance Optimization, and Prospects

“…If a positive voltage is applied to the Pt electrode, the RRAM device is in a high resistance state (Figure b) owing to the broken conductive filament. Yan et al investigated the resistance switching mechanism of Pt/SrTiO 3 /Ag memory devices by X‐ray photoelectron spectroscopy (XPS) and indirectly proved Ag conductive filament mechanism in RRAM devices . The device was placed in high and low resistance states, and the XPS depth profile of Ag and Pt elements was performed on the device.…”

“…Yan et al investigated the resistance switching mechanism of Pt/SrTiO 3 /Ag memory devices by X-ray photoelectron spectroscopy (XPS) and indirectly proved Ag conductive filament mechanism in RRAM devices. [80] The device was placed in high and low resistance states, and the XPS depth profile of Ag and Pt elements was performed on the Figure 3c-e. [91] Long-term potentiation of biological synapses can be achieved by applying successive voltage pulses at periodic intervals of different time periods, indicating that oxide-based atomic switches have the potential to be used asneural computing systems. , and the corresponding simulated diffraction pattern (h).…”

Crossed NiCo2S4 Nanowires Supported on Nickel Foam as a Bifunctional Catalyst for Efficient Overall Water Splitting

“…With the growing energy crisis and severe environmental pollution, great efforts have been devoted to the seeking of replacement with low cost and environmental safety for conventional fossil fuel and alternative energy conversion ,. Hydrogen, a renewable fuel has attracted intense studies owing to advantages like earth abundant, long‐term stability and high efficiency .…”