Electrochemical response of carbon aerogel electrodes in saline water

Abstract

Four carbon aerogels with varied micro/mesoporous texture were synthesized and their electrochemical response for the electro-adsorption of ions investigated in saline electrolyte. As a general trend, the ability of the electrodes to electrosorb ions depended on the microporosity, whereas the large pores (mesopores) had a strong influence on the kinetics of the electrosorption process. The aerogels exhibiting a well developed microporosity interconnected by a large mesoporous network showed large capacitance values and fast electro-adsorption kinetics. Indeed, the diffusion of the ionic species in solution controls the performance of the electrodes at high current loadings (or scan rates). Optimized electrode materials should combine pores within the micropore range to effectively electrosorb ions and large mesopore volumes for a fast diffusion of the ionic species in solution. An adequate meso/micropore ratio in the mesoporous carbon aerogels here reported allowed to record a capacitance value of 75.8 F g-1 .

Effects of CO2 activation of carbon aerogels leading to ultrahigh micro-meso porosity

“…The carbon aerogels have been synthesized by the polycondensation of resorcinol-formaldehyde mixtures in alkaline medium as described elsewhere [16,17]. The effect of the various synthesis and processing conditions on the characteristics (morphology, texture, composition) of the carbon gels has been widely discussed in the literature [19][20][21], and remains out of the scope of this study.…”

“…Details of the preparation of the carbon aerogels by the polymerization of resorcinol (R), formaldehyde (F) and water (W) mixtures using carbonate as catalyst (C) have been reported elsewhere [16,17]. Briefly, the precursors (molar ratio R/C 200, R/W 0.06) were mixed in sealed glass moulds and kept at 40 ºC for 24 h and 70 ºC for 120 h. After a controlled wateracetone exchange, the materials were dried under CO 2 supercritical conditions (sample G4) and carbonized at 800 ºC (sample G4c).…”

Designing micro- and mesoporous carbon networks by chemical activation of organic resins

“…The combination of large specific surface areas (microporosity) with an adequate network of transport pores is desirable to favor diffusion and/or adsorption of bulky molecules of strategic interest in environmental remediation (e.g., hormones, pharmaceuticals, dyes), energy storage and conversion (e.g. electrocatalysis, supercapacitors) and sensing applications (e.g., immobilization of enzymes) (Xin and Song 2015;Liang et al 2008;Pröbstle et al 2002;Rasines et al 2012).…”

Electrosorption for organic pollutants removal and desalination by graphite and activated carbon fiber composite electrodes

“…Trapped by the opposite charge on the electrode surface, the ions in wastewater were adsorbed and fixed in the electrical double layer and subsequently removed from the aqueous phase (Choi and Choi 2010;Nadakatti et al 2011). Generally, activated carbon (Chang et al 2011), activated carbon fiber (ACF) (Li et al 1997), carbon nanotubes (Li et al 2008) and carbon aerogel (Rasines et al 2012) were the most applied electrode materials. Though carbon aerogel and carbon nanotube had the best desalination performance (Farmer et al 1995(Farmer et al , 1996Rasines et al 2012), they suffered from the high cost and were not appropriate for industrial application.…”

“…Generally, activated carbon (Chang et al 2011), activated carbon fiber (ACF) (Li et al 1997), carbon nanotubes (Li et al 2008) and carbon aerogel (Rasines et al 2012) were the most applied electrode materials. Though carbon aerogel and carbon nanotube had the best desalination performance (Farmer et al 1995(Farmer et al , 1996Rasines et al 2012), they suffered from the high cost and were not appropriate for industrial application. Alternatively, surface-modified carbon or carbon-based materials had become the cutting edge for the improvement in electrosorption performance (Ahn et al 2007;Avraham et al 2011;Chang et al 2011;Lee et al 2009).…”