This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Electrolysis can reduce CO2 to CO, a raw material for chemical products such as fuels. Within the GreenQUEST project, an international team led by HZB chemist Prashanth Menezes has systematically investigated catalyst layers made of silver nanoparticles, varying both particle size and density.
In their work published in the journal Advanced Functional Materials, the best yield came from loosely distributed nanoparticles with diameters of around 10 nm. The team also demonstrated how adding a chemical reaction at the anode can improve the economic efficiency of the electrochemical cell, enabling the simultaneous production of formic acid, hydrogen and CO in one device. The greenhouse gas CO2 can be reduced electrolytically to carbon monoxide (CO) using electrical energy.
In subsequent steps, the CO and H₂ generated through electrochemical processes form syngas, which is converted to DME and then catalytically transformed into green-LFG, primarily comprising propane (C₃H₈) and butane (C₄H₁₀). If the electrical energy for electrolysis comes from solar or wind power, this technology can be considered carbon neutral because CO2 is recycled. Teams from HZB are collaborating with partner institutions in South Africa on this technology within the GreenQUEST project.
Their goal is to develop an affordable and sustainable "green" cooking fuel (gLFG) as a cleaner alternative to traditional biomass-based cooking, particularly in rural regions of South Africa where firewood remains an important household energy source. A team led by Menezes at HZB has now demonstrated a way to improve the efficiency and cost-effectiveness of the electrolytic reduction of CO2 to CO. They systematically investigated catalyst layers made of silver nanoparticles, varying both the size of the particles and their density on a carbon powder material that covers the carbon electrode.
"We already knew that too tiny nanoparticles promote hydrogen evolution, which reduces the carbon monoxide yield. Conversely, nanoparticles that are too large are catalytically less active. We wanted to identify the exact optimum," says Dr.
Niklas Hausmann, co-author of the study. The study shows that the best yield came from nanoparticles with diameters of around 10 nm, loosely distributed over the carbon material (0.2 mg per square centimeter of electrode). A second step brought a further improvement.
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