Preparation of N-doped carbon materials from cellulose:chitosan blends and their potential application in electrocatalytic oxygen reduction

Abstract

AbstractCarbon-based electrocatalysts for oxygen reduction reaction (ORR) are prepared by a direct pathway including a two-step thermal treatment process applied to porous spheres of natural biopolymer blends. Cellulose blends with chitosan are first thermally treated at moderate temperatures (e.g., 200 °C), then pyrolyzed at elevated temperature (800–1000 °C), both steps under a constant nitrogen flow. By blending of cellulose with chitosan, the nitrogen content in the final carbon-based catalyst can be considerably increased. The influence of the composition of the precursor biopolymer blend on the ORR electrocatalytic activity is analyzed in correlation with the elemental composition and other structural features of the catalyst. The polymer blend containing cellulose:chitosan = 75:25, thermally treated 1 h at 200 °C and pyrolyzed 1 h at 800 °C under nitrogen atmosphere, shows the highest electrocatalytic ORR activity. This is attributed to an increased surface area combined with relatively high nitrogen content and a higher pyridinic/pyrrolic species ratio.