Pretreatment-controlled structural evolution of cellulose-derived carbon during pyrolysis

Abstract Pretreatment-controlled structural evolution of cellulose-derived carbon was investigated during pyrolysis. Pristine cellulose powder was modified by mechanical ball milling or sulfuric acid hydrolysis before carbonization at 800 o C. Changes in the cellulose precursors and the resulting carbons were examined by thermal analysis, Raman spectroscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, N 2 adsorption-desorption, and energy-dispersive X-ray spectroscopy. The main cellulose bands at about 3400 and 2900 cm -1 remained after pretreatment, indicating that the cellulose backbone was largely preserved before pyrolysis. Acid-derived nanocellulose produced a more disordered carbon with lower accessible surface area, mainly because of aggregation during carbonization. In contrast, ball-milled cellulose produced a more open carbon framework, with an I D /I G ratio of 0.743 and the highest specific surface area of 340.447 m 2 g -1 , dominated by micropores smaller than 2 nm. Among the two pretreatment routes, ball milling led to a more accessible microporous carbon framework after pyrolysis.