Researchers led by Prof. MENG Guowen and Prof. TANG Haibin at the Institute of Solid State Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, have developed self-supported electrodes that improve the conversion of carbon dioxide into carbon monoxide and n-propanol.
The related findings were published in Energy & Environmental Materials and ACS Nano.
Electrocatalytic CO2 reduction uses electricity to convert CO2 into useful chemicals and fuels. However, conventional electrodes often rely on polymer binders, which can affect their performance and stability. Meanwhile, producing multicarbon products such as n-propanol remains particularly challenging.
In this study, the researchers addressed these issues by using a three-dimensional porous anodic aluminum oxide (3D-AAO) template, which has transverse pores interconnecting the longitudinal pores, to make self-supported ordered nanowire array electrodes without polymer binders.
For CO2-to-CO conversion, the team developed a three-dimensional interconnected silver nanowire electrode called 3D-ICAg. The scaffold-like ordered and parallel-arranged silver nanowire array structure provides open pathways for reactants and products, good electrical contact, and rich active sites.
In an H-type electrolytic cell, the electrode achieved a CO Faradaic efficiency of 97.28% with a high current density of 59.06 mA cm-2 and remained stable for 50 hours. In situ Raman spectroscopy was also used to study the reaction process.
The team then used the same approach to develop a three-dimensional interconnected copper nanowire electrode, GB-ICCu, for producing multicarbon products. The electrode contains numerous surface grain boundaries, which help activate CO2 and promote carbon-carbon bond formation. Combined with the nanoconfinement effect induced by the interconnected nanowire, the electrode achieved an n-propanol Faradaic efficiency of 17.47% in an H-type electrolytic cell. In a flow cell, its partial current density reached 77.7 mA cm-2.
The two works demonstrate the potential of self-supported nanowire electrodes for CO2 electroreduction. By removing polymer binders and using a three-dimensional scaffold-like structure, the electrodes provide better access to active sites and improve the movement of reactants and products, while also maintaining stable operation.
Schematic illustration of the synthesis process of the GB-ICCu electrode (Image by TANG Haibin)
