Turning waste into value: Fabrication of gas diffusion electrodes from biomass-derived materials for CO₂ electroreduction to formate

Climate change, driven predominantly by anthropogenic activities such as fossil fuel combustion, has led to significant greenhouse gas emissions. In response, the United Nations' COP28 has set an ambitious goal to reduce emissions by 43 % by 2030, with the aim of limiting global temperature rise to 1.5 °C. Among the various CO₂ mitigation strategies, Carbon Capture and Utilization (CCU) is particularly promising, especially the electrochemical reduction of CO₂ into valuable chemicals. This process not only curtails CO₂ emissions but also facilitates the production of renewable chemicals such as formic acid and formate. Gas diffusion electrodes (GDEs) are central to CO₂ electroreduction, with the microporous layer playing a critical role in preventing flooding and optimizing catalyst interaction. However, traditional carbon black-based microporous layers, such as those made from Vulcan XC-72R, raise environmental and health concerns. This study explores the use of biomass-derived materials, specifically lignocellulosic species, processed via hydrothermal carbonization, pyrolysis, and chemical activation. The results show that GDEs incorporating a biomass and Vulcan XC-72R (50 % wt) mixture achieve high formate concentrations (1.8 g·L −1 ) and Faradaic efficiency toward formate (80 %) at 90 mA·cm −2 —performances that are comparable to or even superior to those of GDEs made solely with commercial Vulcan XC-72R. This demonstrates that these sustainable biomass-derived materials have great potential to effectively replace up to 50 % of carbon black materials and thereby reducing reliance on non-renewable resources, for the production of high-value chemicals from CO 2 . • Biomass-derived materials enhance CO₂ electroreduction efficiency and performance. • GDEs with biomass and Vulcan XC-72R achieve high formate yield and Faradaic efficiency. • Biomass-based microporous layers provide an eco-friendly alternative to carbon black. • CO₂ electroreduction with biomass-derived materials offers promising climate mitigation potential. • Sustainable GDEs achieve high formate concentrations (1.8 g·L −1 ) at 90 mA·cm −2 .