Morphological optimization and nitrogen functionalization of vertically oriented CNW for high performance electrical double layer capacitor electrode

Remote Plasma-Induced Synthesis of Self-Assembled MoS2/Carbon Nanowall Nanocomposites and Their Application as High-Performance Active Materials for Supercapacitors

The objective of this study is to investigate the synthesis and influence of MoS2 on carbon nanowalls (CNWs) as supercapacitor electrodes. The synthesis of MoS2 on CNW was achieved by the introduction of hydrogen remote plasma from ammonium tetrathiomolybdate (ATTM) without deterioration of the CNWs. The topographical surface structures and electrochemical characteristics of the MoS2–CNW composite electrodes were explored using two ATTM-dispersed organic solvents—acetonitrile and dimethylformamide (DMF). In this study, CNW and MoS2 were synthesized using an electron cyclotron resonance plasma. However, hydrogen radicals, which transform ATTM into MoS2, were provided in the form of a remote plasma source. The electrochemical performances of MoS2–CNW hybrid electrodes with various morphologies—depending on the solvent and ATTM concentration—were evaluated using a three-electrode system. The results revealed that the morphology of the synthesized MoS2 was influenced by the organic solvent used and affected both the electrochemical performance and topographical characteristics. Notably, considerable enhancement of the specific capacitance was observed for the MoS2 with open top edges synthesized from DMF. These encouraging results may motivate additional research on hybrid supercapacitor electrodes and the rapid synthesis of MoS2 and other transition metal dichalcogenides.

Innovative Method Using Adhesive Force for Surface Micromachining of Carbon Nanowall

 The application of a carbon nanowall (CNW) via transfer is very demanding due to the unusual structure of vertically grown wall-shaped that easily collapses. In addition, direct growth on a device cannot obtain a precision-patterned shape because of the temperature limit of the photoresist (PR). Therefore, in this paper, we demonstrate a new CNW surface micromachining technology capable of direct growth. In order to reduce unexpected damage caused by chemical etching, a physical force was used to etch with the adhesive properties of CNWs that have low adhesion to silicon wafer. To prevent compositing with PR, the CNW was surface modified using oxygen plasma. Since there is a risk of surface-modified CNW (SMCNW) collapse in an ultrasonic treatment, which is a physical force, the CNW was coated with PR. After etching the SMCNW grown on PR uncoated area, PR was lifted off using an acetone solution. The effect on the SMCNW by the lift-off process was investigated. The surface, chemical, and structural properties of PR-removed SMCNW and pristine-SMCNW were compared and showed a minimal difference. Therefore, the CNW surface micromachining technique was considered successful.