Membranes

Researchers from The University of Warwick, the University of Manchester, Brazil's Universidade Federal do Ceara and Turkey's Izmir Institute of Technology have tackled the long-standing conundrum of why graphene is so much more permeable to protons than expected by theory. 

A decade ago, scientists at The University of Manchester demonstrated that graphene is permeable to protons, nuclei of hydrogen atoms. The unexpected result sparked a debate because theory predicted that it would be extremely hard for a proton to permeate through graphene's dense crystalline structure. This had led to suggestions that protons permeate not through the crystal lattice itself, but through the pinholes in its structure.

Researchers at  Oak Ridge National Laboratory (ORNL) and Arizona State University have developed a technique that combines two approaches to nanofabrication - top-down and bottom-up methods - to enable atomic-scale precision manufacturing using a focused electron beam.

Top-down methods, such as lithography, employ external influences to modify materials. While they offer precision patterning, their resolution is often constrained by factors like beam size and scattering effects. On the other hand, bottom-up methods capitalize on the spontaneous self-assembly of atoms and molecules through chemical reactions, granting atomic-level control. However, the positioning in this method tends to be random rather than directed.
The novel technique demonstrated on twisted bilayer graphene (TBG) harmoniously integrates these two approaches.

A team of researchers from Japan's Chiba University, led by Associate Professor Tomonori Ohba and including master’s students, Mr. Kai Haraguchi and Mr. Sogo Iwakami, has fabricated fullerene-pillared porous graphene (FPPG)—a carbon composite comprising nanocarbons—using a bottom-up approach with highly designable and controllable pore structures. 

Separation processes are essential in the purification and concentration of a target molecule during water purification, removal of pollutants, and heat pumping. To make the separation processes more energy efficient, improvement in the design of porous materials is necessary. Porous carbon materials offer a distinct advantage as they are composed of only one type of atom and have been well-used for separation processes. They have large pore volumes and surface areas, providing high performance in gas separation, water purification, and storage. However, pore structures generally have high heterogeneity with low designability, which poses various challenges, limiting the applicability of carbon materials in separation and storage.

Graphene-Info is happy to give the stage to talented young graphene researchers, especially with such commitment and passion as Roberto Pezone from TU Delft, who has agreed to chat with us and answer a few questions about his background, work and collaboration with the Graphene Flagship.

Roberto Pezone checking a wafer at its initial fabrication stages

Q: Thank you for this interview Roberto! Very nice to e-meet you. We know you have been involved with graphene research for some time, can you give us a quick overview of your graphene research interests and projects?

Thank you for the opportunity to discuss my research. Within the Graphene Flagship's Work Package 6 (core 3), my primary focus lies in integrating graphene into sensors, particularly microphones. My main objective is to develop methods that enable the seamless integration of graphene on a wafer-scale while thoroughly exploring the advantages and disadvantages associated with such approaches.

In addition to developing fabrication techniques, I am also highly interested in characterizing the potential of graphene for acoustic devices. This type of research plays a crucial role in bridging the gap between graphene's exceptional properties and its practical utilization in the industry, unlocking higher performance and new sensor concepts.

UK-based Evove, developer of a graphene-based water filtration technology designed to tackle water shortage, has announced that it has secured £5.7 million (around USD$6,750,000) in a round of funding led by One Ventures with participation from AM Ventures and existing investors.

Evove says it will use the funds to expand its manufacturing capacity, scale up its 3D-printed membrane process, and capitalize on its substantial pipeline of opportunities. 

SoundCell, a spin-off of TU Delft, has secured funding of €350,000 from proof-of-concept fund UNIIQ, together with Delft Enterprises. The funds will go towards facilitating the development of its graphene technology for single cell resolution antibiotic sensitivity testing.

SoundCell develops innovative technology that can measure the vibrations produced by living bacteria. This technology makes use of graphene membranes and could have significant implications for the detection and prevention of antibiotic resistance, as it would enable patients to receive effective medication against bacterial infections faster than today’s standard.

Researchers from Australia's Monash University and CSIRO Manufacturing have designed a permselective membrane based on reduced graphene oxide (rGO) for making practical lithium-sulfur batteries. 

The membrane closely mimics a cell plasma membrane, demonstrating selective Li+ transport and the ability to not only retain polysulfides, but also 're-activate' them on the membrane's electrochemically active interface. The team used the membrane to demonstrate high loading and high rate Li-S batteries, also on a pouch cell level.

Researchers from Lawrence Berkeley National Laboratory and University of California at Berkeley recently used graphene to develop an imaging platform that enabled nondestructive spectroscopic imaging of soft materials with nanometer spatial resolution, under in vitro conditions and external stimuli. Using the Advanced Light Source (ALS) particle accelerator as an infrared light source, the researchers performed the nanometer-scale spatial resolution imaging of proteins in the proteins’ natural liquid environment. They observed how the self-assembly of the proteins was affected by environmental conditions in the surrounding liquid.

Current imaging tools often use ionizing radiation under conditions that are far from the molecule’s native biological environment. Powerful imaging techniques such as fluorescence microscopy can potentially damage biological material, and they often do not provide chemical information. To resolve this challenge, the researchers combined nano-Fourier transform infrared (nano-FTIR) spectroscopy with graphene-capped liquid cells. The imaging platform could open opportunities in the study of soft materials for sectors that range from biology to plastics processing to energy.

Scientists from Vanderbilt University recently developed a lightweight and ultra-compact graphene-based filter that can block aerosolized nanoparticles of size in the sub-20 nm range. 

Nanoparticulate aerosols contain toxins, pollutants, and harmful viruses, whose size varies between 20 and 300 nm in diameter. Although conventional air filters, such as 95% efficiency filter (N95) and the high-efficiency particulate air filter (HEPA), exhibit superior air flow rates, they are unable to inhibit nanoparticulate aerosols whose size is less than 300 nm. Facemasks that can block nanoparticulate aerosols of size below 300 nm are bulky and develop thermal stress due to low breathability. To improve the applicability of PPEs, several strategies are implemented that focus on making porous polymers, with greater thickness, which can filter out nanoparticulate aerosol toxins, pathogens, and pollutants.

Researchers from University College London have demonstrated a graphene nanomesh membrane that possesses high hydrophilicity, super-oleophobicity and low oil adhesion underwater.

The researchers in this work have put a nature-inspired spin on the fabrication of high-performance graphene membranes for tricky oil/water separations even in stable emulsions. They demonstrated graphene nanomesh membranes within a wide pH range at impressive water permeance (close to 4000 L m2 h1 bar1) under a very low trans-membrane pressure difference.