Structural, composition, optical, electrical, and electrochemical characterization of three-dimensional graphene foam

A comprehensive study is reported of two types of 3D graphene foams (GF) exhibiting distinct defect density, structural and functional properties. Wettability characterization demonstrates high and low defect GF are hydrophilic, with a contact angle (CA) of approximately 14° and 72° respectively. Optical characterization demonstrates close to zero reflectance and transmittance over 350 nm to 25 μm spectral X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDS), provides insight into chemical composition, defect density, and functionalization, while atomic force microscopy (AFM) shows the high defect GF (HDGF) has a pronounced surface roughness, with a maximum surface roughness of over 18 nm. While the low defect GF (LDGF) exhibits a significantly smoother and more uniform surface with a maximum surface height of 4.5 nm. Electrochemical characterization demonstrates the impact of network connectivity on charge transport, highlighting differences in resistance and percolation thresholds between the two HDGF and LDGF foam types with arial capacitances of 38 and 32 µFcm-2 respectively at current density of 0.1 mAcm-2. The values hold 90% and 94% retention of the initial capacitance when current density was increased 50 folds. A detailed structure–property–function relationship is established for the GF materials, useful for various applications.