In order to extract valuable materials from CO2, it must undergo a series of reduction steps. Utilizing electrocatalysis for this purpose can generate numerous different molecules, many of which may not be useful. Conversely, biocatalysts produce a single, specific product but are also quite sensitive to conditions. An international research team has now created a hybrid catalysis cascade that leverages the strengths of both methods.
To retrieve valuable materials from CO2, numerous reduction steps are necessary. When electrocatalysis is applied, it results in various potential molecules that may not all be suitable for use. In contrast, biocatalysts are selective, yielding only one product—but they possess a high level of sensitivity. An international research team, led by Professor Wolfgang Schuhmann from the Center for Electrochemistry at Ruhr-Universität Bochum, Germany, along with Dr. Felipe Conzuelo from the Universidade Nova de Lisboa, Portugal, has engineered a hybrid catalysis cascade that combines the benefits of both approaches. Their findings were published in the journal Angewandte Chemie International Edition on December 23, 2024.
Pros and Cons of Electrocatalysis and Biocatalysis
Methanol is a desired product that we aim to produce from carbon dioxide, which contributes to climate change. It is frequently utilized as a raw material for synthesis in the chemical sector. “Producing methanol requires numerous reduction steps because carbon dioxide represents the most oxidized state of carbon,” states Wolfgang Schuhmann. Electrocatalysis can initiate these processes. Although it remains selective during the initial step, the reaction subsequently branches out, leading to the formation of up to 16 different products, which may not include methanol. In contrast, biocatalysts, which are natural enzymes, facilitate only one reaction, resulting in a single product. However, they can be difficult to manage, are very sensitive, and may need cofactors to carry out the reaction effectively.
Integrating Both Methods
To merge the advantages of these two methods, the research team, under the guidance of first authors Panpan Wang and Xin Wang, combined electrocatalysis with biocatalysis. The initial reaction step transforming CO2 into formate utilizes electrocatalysis. The subsequent second and third steps are catalyzed by the enzymes formaldehyde dehydrogenase and alcohol dehydrogenase. These enzymes require NAD (nicotinamide adenine dinucleotide) as a cofactor, which is consumed throughout the catalytic process and necessitates regeneration. A third enzyme is responsible for this regeneration. Ultimately, the valuable product obtained is methanol. “This work demonstrates the feasibility of such hybrid cascades and showcases their potential in enabling complex, selective multi-step reactions,” concludes Wolfgang Schuhmann.
