Functionalized nanostructured carbons were obtained by template method using sucrose as carbon precursor and silica gel SG60 as structure directing agent. To introduce acid groups into carbon a different amount of phosphoric acid was added to sucrose (impregnation ratio 0-1) before filling the pores of silica gel. After carbonization at 800 °C silica template was removed by dissolution in HF. Carbons were characterized by SEM/EDX, nitrogen adsorption at 77 K and acid-base titration. Pore size distributions (PSD) indicated that carbons obtained at impregnation (IR) of 0-0.75 have pores with size less than 4 nm due to crack during carbonization and activating action of phosphoric acid. Templated pores with 5.1 nm are observed in all carbons. PSD significantly changed at IR = 1 showing additional large mesopores of 8.2 nm. Acid-base titration revealed very high concentration of acid surface groups (4.1-4.7 mmol/g), significant amount of which (46 ± 3%) belongs to phosphate groups (pK = 2.3 ± 0.1). Another surface groups are weak carboxylic (pK = 5.9 ± 0.3), lactone and/or enol (pK = 7.2 ± 0.2, pK = 8.8 ± 0.3) and phenol groups (pK = 10.5 ± 0.3). SEM showed smooth carbon surface up to impregnation ratio 0.5 and increasing roughness at higher amount of phosphoric acid.
ASJC Scopus subject areas
- Materials Science(all)