Highly selective and high-performance osmotic power generators in subnanochannel membranes enabled by metal-organic frameworks

The electric organs of electric eels are able to convert ionic gradients into high-efficiency electricity because their electrocytes contain numerous subnanoscale protein ion channels that can achieve highly selective and ultrafast ion transport. Despite increasing awareness of blue energy production through nanochannel membranes, achieving high-performance energy output remains considerably unexplored. Here, we report on a heterogeneous subnanochannel membrane, consisting of a continuous UiO-66-NH2 metal-organic framework (MOF) and a highly ordered alumina nanochannel membrane. In the positively charged membrane, the angstrom-scale windows function as ionic filters for screening anions with different hydrated sizes. Driven by osmosis, the subnanochannel membrane can produce an exceptionally high Br-/NO3- selectivity of similar to 1240, hence yielding an unprecedented power of up to 26.8 W/m(2) under a 100-fold KBr gradient. Achieving ultrahigh selective and ultrafast osmotic transport in ion channel-mimetic MOF-based membranes opens previously unexplored avenues toward advanced separation technologies and energy-harvesting devices.

Automated summary

By developing a heterogeneous subnanochannel membrane with highly selective ion transport capabilities, researchers have achieved unprecedented power output of up to 26.8 W/m(2) under a 100-fold KBr gradient. This membrane, consisting of a continuous UiO-66-NH2 metal-organic framework and an orderly alumina nanochannel membrane, demonstrates the potential for advanced separation technologies and energy-harvesting devices.