Modification of hydrophobic/hydrophilic properties of Vulcan XC72 carbon powder by grafting of trifluoromethylphenyl and phenylsulfonic acid groups

Electrochemical Oxidation of the Carbon Support to Synthesize Pt(Cu) and Pt-Ru(Cu) Core-Shell Electrocatalysts for Low-Temperature Fuel Cells

“…This irreversible nature was further confirmed when performing consecutive cyclic voltammograms, in which a significant current decrease was apparent cycle by cycle (not shown here). It has been reported in the literature that the cathodic peak currents in the range 0.4-0.6 V are due to the reduction of the quinone phenolic groups of carbon to hydroquinone [18,19,35,36,38,[42][43][44][45]. When the anodic and the cathodic limits were limited to the range 0.4-0.7 V, the transformation between quinone and hydroquinone groups appeared to be reversible.…”

“…On the other hand, the less acidic groups increase the interaction between the metal precursor and the carbon support, thus avoiding the agglomeration tendency of the metal on the carbon [1,40]. The functionalization of the carbon surface can be achieved by treatment with strong oxidizing acids such as nitric, sulfuric, phosphoric, sulphonic, or their mixtures, or by means of sodium hydroxide, ammonia, or hydrogen peroxide [18,[27][28][29]35,36,38,[40][41][42][43][44][45][46]. Oxygen or oxygen plus nitrogen mixtures, thermal oxidation [18,38], and electrochemical oxidation at constant current or potential, potential pulses, or potential cycling have also been applied [28,34,42,45,47].…”

“…Pt(IV) and Ru(III) species or their carbonyl complexes can be reduced in ethylenglycol or formate solutions [11,13,30], also using in some cases oil in water microemulsions [31], microwave radiation [15], or galvanic exchange [32][33][34]. However, carbon blacks and active carbons have been the mostly employed supports for low-temperature fuel cells due to their unique characteristics of high surface area, electric conductivity, porosity, stability, and low cost [1,3,10,16,22,30,35,36]. The morphology and size distribution of carbon black particles depend on the raw material and on the thermal decomposition process utilized in the synthesis procedure.…”

“…Hydroquinone (HQ) C6H4(OH)2 groups, which can be oxidized to quinone (Q) C6H4O2 groups, can also improve the electrocatalytic properties and the stability of the catalysts in the operation conditions of the fuel cells [18,19,35,36,38,[42][43][44][45]:…”

“…Vulcan carbons XC-72 and XC-72R [37] are carbon blacks obtained from the pyrolysis of natural gas or oil fractions. They can be considered rather graphitic amorphous forms of carbon with spherical shape about 50 nm in diameter that can be aggregated in spherules of about 250 nm in size [30,36]. Vulcan XC-72R has suitable surface and micropore areas of 218 and 65.2 m 2 g −1 , respectively, and pore, mesopore, and micropore volumes of 0.41, 0.3,7 and 0.036 cm 3 g −1 , respectively [19,37,38].…”