Three dimensional graphene aerogels and their electrically conductive composites

The Role of Diamines in the Formation of Graphene Aerogels

“…The G band in some spectra appeared clearly asymmetric due to the contribution of D' band, while both D and G bands in rGO DAB , rGO OPD aerogels are contaminated by signals probably due to the presence of aromatic diamines. The characteristic I D /I G ratio (I D and I G were measured from the peak height after baseline correction) was increased from 0.78 in pure GO to 0.86-1.19, similarly to other rGO products in the literature (Stankovich et al, 2007;Pei and Cheng, 2012;Tang et al, 2014;Abdolhosseinzadeh et al, 2015;Bo et al, 2015;Ji et al, 2017). That change is usually attributed to the decrease of average size of sp 2 domains, together with an increase of the number of those domains after reduction (Stankovich et al, 2007;Pei and Cheng, 2012;Chen et al, 2013;Feng et al, 2013).…”

“…ammonium hydroxide) using ultrasonication for 1 h. After addition of diamine (0.1 mmol), the mixture was heated in a sealed bottle at 95 • C for 24 h. The resulting hydrogels were washed several times with water to remove unreacted diamine, and then they were lyophilized for 24 h. The density of final aerogels was determined from their weight and their physical dimensions. (Hu et al, 2013;Tang et al, 2014).…”

“…After reduction/functionalization, the bands assigned to oxygen groups at 1,046, 1,200, 1,710, and 3,200-3,400 cm −1 were significantly reduced in the spectra of rGO's. Covalent grafting of TETA on graphenic layers was indicated by the appearance of characteristic peaks at 2,920, 2,850 cm −1 (-CH 2 -stretch), 1,550 cm −1 (N-H in plane scissoring vibration or bending), (Tang et al, 2014) 1,440 cm −1 (-CH 2 -bend), 1,170 cm −1 and 1,100 cm −1 (C-N stretch). Similar spectroscopic evidence was recorded in other aerogels with aliphatic diamines as shown in Figure 5, indicating analogous covalent functionalization.…”

“…The characteristic peaks of the oxygen groups were remarkably reduced in comparison with GO and several new peaks have been appeared indicating the presence of aromatic diamines in the aerogels. rGO PPD showed peaks at 3,445 cm −1 (OH stretch), 1,624 cm −1 (C=C bending), 1,536 cm −1 (bending vibration of NH, indicating -C-NH-C-formation) (Tang et al, 2014), 1,500 cm −1 (phenyl ring vibration), 1,420 (C-N stretch), 1,100, cm −1 (-CO stretch), (Lu et al, 2014), and 873 cm −1 (CH non-planar ring vibrations; see Figure 6). …”

“…Thereby, graphene aerogels are 3D architectures consisting of a conducting network of rGO nanosheets with large specific surface areas and micro/nano porosity Shi, 2012, 2014;Pei and Cheng, 2012;Zhang et al, 2012;Nardecchia et al, 2013;. Graphene aerogels are attracting much attention for applications in catalysis, environmental remediation, energy storage (supercapacitors, Li ion batteries) as well as in sensors and biosensors (Chen et al, 2013;Hu et al, 2013;Sun et al, 2013;Tang et al, 2014). Usually, graphene gelation is assisted by hydrophilic polymers or small organic molecules, although rGO hydrogels without such promoters have also been reported (Liu and Seo, 2010).…”