Two-Dimensional WO₃ Nanosheets Chemically Converted from Layered WS₂ for High-Performance Electrochromic Devices

Area of Science:

• Materials Science
• Nanotechnology
• Electrochemistry

Background:

• Two-dimensional (2D) transitional metal oxides (TMOs) offer high surface area and enhanced properties.
• 2D tungsten oxide (WO3) nanosheets show promise for electrochromic (EC) devices.
• Producing 2D WO3 is difficult due to WO3's inherent 3D structure.

Purpose of the Study:

• To develop a novel synthesis method for 2D WO3 nanosheets.
• To evaluate the performance of 2D WO3 nanosheets in EC devices.
• To understand the enhancement mechanism in EC devices.

Main Methods:

• Solution-phase synthesis of 2D WO3 nanosheets via oxidation of exfoliated 2D WS2 nanosheets.
• Crystallographic and elemental analyses to confirm WS2 to WO3 conversion.
• Fabrication and testing of EC devices using 2D WO3 nanosheets.

Main Results:

• Successfully synthesized 2D WO3 nanosheets from 2D WS2 nanosheets.
• EC devices with 2D WO3 showed a 62.57% color modulation at 700 nm (3.43x higher than bulk WO3).
• Switching response times were enhanced by ~46.62% (coloration) and ~62.71% (bleaching).

Conclusions:

• The novel synthesis route enables efficient production of 2D WO3 nanosheets.
• 2D WO3 nanosheets significantly outperform bulk WO3 in EC devices.
• The enhanced performance is attributed to the reduced thickness of the WO3 nanosheets.