Graphene-based catalyst for CO₂ reduction: The critical role of solvents in materials design

The catalytic reduction of carbon dioxide (CO₂) to hydrocarbon fuels offers a tremendous opportunity for a transformational impact on both global energy and environmental sustainability. To enhance the CO₂ reduction process, the design and synthesis of novel and efficient catalytic materials with control-over properties are needed. The solvent used in the synthesis of these materials can play a crucial role in tailoring the material properties resulting in changes to their catalytic performance. However, the field still lacks a systematic analysis of the specific effect for different solvents. Here, we report the role of water, ethanol (EtOH), ethylene glycol (EG), Dimethylformamide (DMF), and γ-Butyrolactone (GBL) on the synthesis of reduced graphene oxide (rGO)-copper nanoparticles (CuNP) electrocatalysts used in CO₂ reduction reactions (CO₂RR). As these solvents contain different terminal groups and molecular sizes, we observed a variation in the d-spacing of the rGO, surface area, nanoparticle yield, and defect density, and characterized the corresponding change in the CO₂RR activity. The use of DMF results in higher porosity, d-spacing, yield of CuNP, surface area and defect density which lead to comparatively higher efficiency and selectivity of and selectivity of 19.5 % and 28.4 % for formate and CO, respectively.