Fast light-switchable polymeric carbon nitride membranes for tunable gas separation

Simuli-responsive separation membranes often suffer from slow response times or require high energy input for switching to occur. Here authors demonstrate light-switchable gas separation membranes based on polymeric carbon nitride with fast switching times for the efficient separation of gases with higher polarizabilities. Switchable gas separation membranes are intriguing systems for regulating the transport properties of gases. However, existing stimuli-responsive gas separation membranes suffer from either very slow response times or require high energy input for switching to occur. Accordingly, herein, we introduced light-switchable polymeric carbon nitride (pCN) gas separation membranes with fast response times prepared from melamine precursor through in-situ formation and deposition of pCN onto a porous support using chemical vapor deposition. Our systematic analysis revealed that the gas transport behavior upon light irradiation is fully governed by the polarizability of the permeating gas and its interaction with the charged pCN surface, and can be easily tuned either by controlling the power of the light and/or the duration of irradiation. We also demonstrated that gases with higher polarizabilities such as CO2 can be separated from gases with lower polarizability like H-2 and He effectively with more than 22% increase in the gas/CO2 selectivity upon light irradiation. The membranes also exhibited fast response times (<1 s) and can be turned on and off using a single light source at 550 nm.

Automated summary

This study demonstrates light-switchable gas separation membranes based on polymeric carbon nitride with fast response times and efficient separation performance.