A high-performance hydroxide exchange membrane enabled by Cu²⁺-crosslinked chitosan.

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Ion exchange membranes are crucial for electrochemical devices.
• Hydroxide exchange membranes (HEMs) are ideal for platinum-free electrocatalysts but lack alkaline stability.

Purpose of the Study:

• To develop a stable and high-performance hydroxide exchange membrane (HEM).
• To investigate the potential of copper-crosslinked chitosan as a HEM material.

Main Methods:

• Chitosan was crosslinked with Cu²⁺ ions to form nanochannels.
• The material's ion conductivity, mechanical strength, and alkaline stability were evaluated.
• Performance was tested in a direct methanol fuel cell.

Main Results:

• The chitosan-Cu membrane exhibited a hydroxide conductivity of 67 mS cm⁻¹ at room temperature.
• It demonstrated excellent stability in alkaline solutions, with only 5% conductivity loss after 1,000 hours at 80°C.
• The membrane achieved a high power density of 305 mW cm⁻² in a direct methanol fuel cell.

Conclusions:

• Copper-crosslinked chitosan is a promising material for stable and high-performance HEMs.
• The metal-crosslinking strategy can inspire the design of novel ion exchange membranes for various applications.