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

Abstract

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 H2 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.

Eutectic Molten Salt Synthesis of Highly Microporous Macrocyclic Porous Organic Polymers for CO2 Capture

“…The presence of −C=O signals indicated the presence of end‐groups and unreacted keto‐groups. Additionally, the high‐resolution N1s spectra revealed a single peak at 398.4 eV, corresponding to −C−N−/−C=N− and confirming the presence of only phenazine moieties [28,32,33] . The high‐resolution O1s spectra showed peaks at 528.4 and 531.5 eV, which can be attributed to oxidized Indium from the support, varying aluminum oxide species and −C=O moieties [32,34] .…”

“…We also observed the presence of oxygen atoms originating from terminal carbonyl moieties and aluminum oxide species along with trace amounts of other elements ( Figure S3 ). The high‐resolution C1s spectra exhibited peaks at 284.8, 286.4, 288.5, and 291.6 eV, which can be attributed to −C−C−/−C=C−, −C−N−/−C=N−, −C=O, and π–π* interactions, respectively ( Figure 1 c ) [32,33] . The presence of −C=O signals indicated the presence of end‐groups and unreacted keto‐groups.…”

“…The high-resolution C1s spectra exhibited peaks at 284.8, 286.4, 288.5, and 291.6 eV, which can be attributed to À CÀ CÀ /À C=CÀ , À CÀ NÀ /À C=NÀ , À C=O, and π -π* interactions, respectively (Figure 1c). [32,33] The presence of À C=O signals indicated the presence of end-groups and unreacted keto-groups. Additionally, the high-resolution N1s spectra revealed a single peak at 398.4 eV, corresponding to À CÀ NÀ /À C=NÀ and confirming the presence of only phenazine moieties.…”

“…Additionally, the high-resolution N1s spectra revealed a single peak at 398.4 eV, corresponding to À CÀ NÀ /À C=NÀ and confirming the presence of only phenazine moieties. [28,32,33] The high-resolution O1s spectra showed peaks at 528.4 and 531.5 eV, which can be attributed to oxidized Indium from the support, varying aluminum oxide species and À C=O moieties. [32,34] Overall, the FT-IR and XPS spectra provide compelling evidence for the successful formation of 3D-mmPOPs and the presence of a small number of unreacted keto-groups.…”

Photocharging of Carbon Nitride Thin Films for Controllable Manipulation of Droplet Force Gradient Sensors

“…Carbon nitride is a metal-free semiconducting polymer, and its structure primarily consists of 2D graphitic-like planes of cross-linked heptazine units (Figure a), which causes anisotropy of electronic transport, enabling long-lived surface charges. High extinction coefficients in the UV range enable splitting electrons and holes between thin layers, , resulting in a collective net charge by graphitic planes. , Upon UV illumination of a carbon nitride-coated glass slide covered with an aqueous sodium dodecyl sulfate (SDS) surfactant solution, looking through an air bubble, we observed rapid de-wetting and spreading of the bubble occurring exclusively within the illuminated areas of the sample (Figure c). In the same experiment, without any surfactant present, no response is observed (Movie S1).…”