Mg²⁺-selective COF membrane

Near-ideal selectivity

Combines selective Mg²⁺ transport with high permeability via ordered nanochannels with O/N coordination sites and hydrogen-bond networks, enabling both osmotic power generation and iontronic logic control.

Yang, Lixue · Xu, Yixin · Du, Yan · Feiyao, Yang · Zhou, Yanguang · Wang, Zhe · Wang, Zhonglin · Wei, Di

Small 2026

Specifications

Mg²⁺ transference number (t₊)

{'zh': '0.98', 'en': '0.98'}

Osmotic power density

{'zh': '636.64', 'en': '636.64'} W m⁻²

Current density

{'zh': '9213.3', 'en': '9213.3'} A m⁻²

Nanochannel diameter

{'zh': '13.6', 'en': '13.6'} Å

Advantages

Near-ideal Mg²⁺ selectivity

Transference number of 0.98 means almost only Mg²⁺ passes, enabling high-purity separation.

Ultrafast transport

O/N coordination partially strips the hydration shell and C=O···H─O─H hydrogen-bond networks lower migration barriers, enabling fast Mg²⁺ transport.

Record osmotic power density

Delivers 636.64 W m⁻² under 500-fold salinity gradient, offering a high-performance membrane for osmotic energy conversion.

Dual functionality: power and logic

The same membrane enables both osmotic power generation and iontronic transistors/logic operations, bridging energy conversion and information processing.

Applications

• Osmotic power generation：Delivers high power density under 500-fold salinity gradient, directly usable for osmotic power generation.
• Iontronics：Mg²⁺-selective nanochannels enable iontronic transistors and logic operations.
• Ion sensing：Selective ion transport can be used for sensing or regulating Mg²⁺ concentration.
• Salinity gradient energy conversion：Converts salinity gradients directly into electricity with high efficiency.