Abstract:

In this paper， the effects of three different anodic materials （copper wire， galvanized steel and nickel wire） on the structure and morphology of carbon materials prepared by electrochemical reduction of CO₂ in molten salt were studied. Three carbon structures， e.g.， hollow quadrilateral carbon （HQC，the product with Cu as an anode）， carbon nanosheet （CNS， the product with galvanized steel as an anode） and sponge porous carbon （SPC， the product with Ni as an anode）， were prepared， and their electrocatalytic properties towards the two-electron oxygen reduction reaction （2e^- ORR） were explored. The results show that the CNS prepared by using galvanized steel as the anode material is composed of a large number of carbon nanosheets， in which there are abundant pore structure defects. Compared with HQC and SPC， CNS shows the highest 2e^- ORR electrocatalytic activity and H₂O₂ selectivity （close to 90%）. The high activity and selectivity of CNS are attributed to its high I_D/I_G （I_D/I_G is the ratio of the intensity of D peak and G peak in Raman spectrum， and its ratio reflects the defective degree of the material） value and high C—O/CO ratio， indicating that structural defects and C—O/CO functional groups are crucial to the catalytic performance of CNS. In addition， CNS exhibits excellent electrocatalytic stability， and the ring current almost does not decay after 14 hours potentiostatic test. The use of CO₂ as the carbon source to synthesize electrocatalytic carbon materials not only can be used as a potential option to mitigate the greenhouse effect， but also provide a new idea for the practical application of CO₂ derived carbons.

Key words: Electrochemical reduction, Carbon dioxide, Carbon materials, Hydrogen peroxide