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Researchers at Lawrence Livermore National Laboratory (LLNL) began using 3D printing to produce continuous flow electrodes (FTE) for electrochemical reactors, which is said to have improved reactor performance up to 100 times.

Using direct ink writing, in particular, the LLNL team were able to 3D print custom porous electrodes made from graphene airgels. Imprinted structures are crucial for a whole series of electrochemical reactions, such as the conversion of CO2 and other molecules into useful energy products.

By taking advantage of the design freedom offered by additive manufacturing, researchers found they could better control the flow through their 3D printed ETPs. In the context of an electrochemical reactor, this can mean improving mass transfer and maximizing reactor performance.

“We are pioneers in the use of 3D reactors with precise control of the local reaction environment,” explains LLNL engineer Victor Beck, lead author of the study. “New high performance electrodes will be essential components of next generation electrochemical reactor architectures. This demonstrates how we can take advantage of the control offered by 3D printing over the electrode structure to design the local fluid flow and induce complex inertial flow models that improve reactor performance.

Mass transfer and electrochemical reactors

Electrochemical reactors are generally used to convert chemical reactants into a more useful form of energy, namely electricity or fuel. According to LLNL researchers, the commercial viability of these reactors largely depends on achieving greater mass transfer, which is simply defined as the transport of fluid reagents to reactive surfaces through electrodes. For this, we need ETP capable of controlling and engineering flows.

Until now, ETPs have been made using “messy media” such as carbon fiber based foams and felts. Although cost effective, these randomly ordered materials often result in an uneven distribution of flow rate and mass transfer, which impairs reactor performance.

By opting instead for 3D printed airgel electrodes, the researchers demonstrated that they could customize ETP flow channel geometries to optimize reactions in the reactor, while mitigating the shortcomings of traditionally manufactured ETPs.

“Achieving precise control over electrode geometry will allow advanced engineering of electrochemical reactors that was not possible with previous generation electrode materials,” adds co-author Anna Ivanovskaya. “Engineers will be able to design and manufacture structures optimized for specific processes. Potentially, with the development of manufacturing technology, 3D printed electrodes can replace conventional messy electrodes for liquid and gas type reactors.

3D printed graphene airgels ETP

ETPs were printed in complex lattice structures, which are said to have improved mass transfer by 1 to 2 orders of magnitude (10x – 100x) compared to previous 3D printing attempts. LLNL ETPs also achieved reactor performance comparable to conventional disordered materials, which is a very promising result.

Swetha Chandrasekaran, co-author of the study, said: “By 3D printing advanced materials such as carbon aerogels, it is possible to design macroporous networks in these materials without compromising physical properties such as electrical conductivity. and the surface.

The team said the success of the study will now allow them to explore the effects of electrode architectures designed without resorting to expensive industrial manufacturing processes. LLNL is also currently working on 3D printing more robust electrodes and other reactor parts using resin-based micro-stereolithography and two-photon lithography techniques.

3D printing of electrodes is not a new concept, although it is still largely limited to the academic sphere. A team of researchers from Oak Ridge National Laboratory and the University of Tennessee has already developed a method of 3D printing electrodes for complementary metal-oxide-semiconductor (CMOS) circuits. Specifically, the scientists used a Nanoscribe Photonic Professional GT two-photon polymerization system to nanoprint polymer structures directly onto semiconductor chips, where they could be carbonized.

Elsewhere, scientists have already 3D printed electrodes capable of detecting mycotoxins in food, paving the way for a new method of ensuring food safety. The toxic metabolite is produced by Fusarium species of fungi and can generally be found in corn products containing wheat such as cereals.

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The image shown shows 3D printed lattice electrode geometries. Image via LLNL.