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Yes: experiments have shown hydrogen passing through supported, single-layer graphene faster than methane. But the best-known demonstration was a small research membrane, not an industrial system. For carbon dioxide, the cited nanopore designs are computational proposals—not proof that graphene membranes have separated CO2 from flue gas in practice.
How graphene nanopores separate gases
Defect-free graphene blocks ordinary gas molecules. Carefully formed nanopores create paths through the atom-thin sheet, and different gases cross those pores at different rates because they encounter different energy barriers. A pore therefore does not act only as a simple hole that admits molecules below one exact size: its chemistry and structure influence transport as well.
A 2022 review in Accounts of Materials Research describes theoretical electron-density-gap targets for sieving particular gases. These are design criteria discussed in the review, not universal measured pore diameters or guaranteed cutoffs.
| Gas targeted | Theoretical electron-density gap criterion in the review |
|---|---|
| H2 | Below 0.289 nm |
| CO2 | Below 0.33 nm |
| O2 | Below 0.346 nm |
| N2 | Below 0.362 nm |
| CH4 | Below 0.38 nm |
The review identifies three design needs: a pore gap suited to the target gas, a narrow distribution of pore sizes, and enough selective pores to provide useful flow. Oversized defects can let gases leak through without the intended discrimination; too few pores can restrict throughput.
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What has been demonstrated for hydrogen and methane
A 2018 Nature Communications study reported a method using nanoporous carbon to transfer graphene without cracks onto a macroporous support. The suspended single-layer membrane had a reported active area of 1 mm2 and porosity of 0.025%. In that study, H2/CH4 selectivity reached 25, while the separation factor in a mixed feed reached 18. Reported H2 permeance reached 4.1 × 10−7 mol m−2 s−1 Pa−1.
These figures describe that membrane and its test conditions, not graphene membranes in general. Selectivity compares how readily one gas passes relative to another; permeance describes flow through a membrane for a given pressure difference. Both matter: a high selectivity number alone does not establish that a membrane can process enough gas.
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The same study reported membrane stability during heating and cooling cycles between 25 and 150 °C and with transmembrane pressure differences up to 7 bar. It also used ozone-functionalization-based etching and pore modification; the modified membranes showed reported H2 permeance improvement up to 300% and H2/CH4 selectivity improvement up to 150%. Those gains are specific to the study’s treatment and comparison.
What the CO2 results do—and do not—show
The cited CO2 nanopore work is computational. A 2023 molecular-dynamics study modeled crown-ether-like graphene pores for CO2/CH4 and CO2/CO separation. One modeled pore design transported CO2 while blocking CH4 or CO in most simulated cases. This is a theoretical proposal, not an experimental separation result.
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A separate 2024 density-functional-theory study modeled nitrogen-terminated sub-nanometer graphene pores. It identified 4.5–5.0 Å pores as potentially promising for selected gas separations and discussed larger 5.5–5.7 Å pores for methane separation. These are calculation-derived candidates, not demonstrated operating membranes.
Consequently, the cited evidence does not establish that single-layer graphene nanopores capture CO2 from real flue gas. The modeled gas pairs and computational results should not be treated as a tested flue-gas process.
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- Single-layer graphene sheet with over 97% transmittance, ideal for optical applications and sensor technology.
- Monolayer graphene film with a theoretical thickness of just 0.345nm, providing exceptional electrical and thermal properties.
- Compatible with various substrates including copper, glass, Si, SiO2, PET, and quartz, ensuring versatility in research applications.
- Exhibits ultra-high strength and thermal conductivity, making it one of the most advanced materials for scientific research.
- Packaged as 1 piece per package, perfect for laboratory use and experimental setups.
Evidence by membrane type
Several graphene-related results are often easy to conflate. The evidence and material architecture matter as much as the headline performance value.
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| Approach | Evidence and reported result | What it supports |
|---|---|---|
| Supported, single-layer nanoporous graphene | 2018 experimental study: H2/CH4 selectivity up to 25 and mixed-feed separation factor up to 18; reported H2 permeance up to 4.1 × 10−7 mol m−2 s−1 Pa−1. | A research-scale experimental demonstration of hydrogen/methane separation. |
| Edge-functionalized graphene nanopores | 2025 study combining experiments and modeling: H2/SF6 selectivity reached 39.4 at 150 °C in that study’s membrane and conditions. | A reported high-temperature hydrogen-separation result, not a general benchmark. |
| Modeled graphene nanopores | 2023 molecular-dynamics work proposed crown-ether-like pores for CO2/CH4 and CO2/CO. A 2024 DFT study modeled nitrogen-terminated pores. | Computationally promising designs that still require experimental validation. |
| Graphene/MOF/polymer mixed-matrix membrane | 2024 Chemosphere study: graphene nanosheets and MIL-125-NH2 in a PES polymer matrix. Reported permeability increases were 36% for CO2, 41% for N2, 31% for CH4, and 370% for H2; the best reported selectivity improvement was 236% at 0.05 wt% graphene. | Results for a polymer composite, not for a single graphene sheet with engineered nanopores. |
The mixed-matrix study measures a different architecture: graphene nanosheets and a metal-organic framework are incorporated into polymer. Its permeability and selectivity results can inform work on graphene-containing membranes, but they cannot be presented as performance measurements of nanoporous single-layer graphene.
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What stands between a laboratory membrane and deployment
The central engineering problem is to make a large, intact graphene layer and create a controlled population of selective pores in it. Cracks or a small number of oversized defects can bypass the intended molecular sieve; an insufficient density of selective pores can limit throughput. Both pore quality and pore density therefore have to be managed together.
The 2018 transfer study’s reported 1 mm2 active area illustrates the scale of that particular demonstration. It does not, by itself, establish performance across larger support areas or prove that selectivity and permeance can be maintained during industrial operation. The computational CO2 proposals likewise do not establish a working process, and the mixed-matrix results concern a different membrane structure.
The cited studies document laboratory experiments and theoretical designs, not economic or commercial-scale deployment. For an industrial claim, evidence would need to show intact larger-area membranes, controlled pores, useful selectivity and permeance together, and performance under relevant feed and operating conditions.
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