Expanding the interlamellar spacing of biomass-derived hybrids with intercalated nanotubes for enhanced oxygen reduction reaction

Biomass has been regarded as a promising precursor for preparing eletrocatalysts due to their rich carbon content and availability. However, it is a challenge to regulate the porous structure and modify the active sties. In this work, a carbon nanotube (CNT)-intercalated strategy was proposed to inhibit the stacking of the glucose-derived carbon sheet using dicyandiamide as the structure directing agent. The reaction of dicyandiamide with glucose inhibits the transformation of glucose to carbon spheres, increasing the density of accessible active sites. Meanwhile, in situ grown CNTs from decomposed dicyandiamide segment under the catalysis of cobalt nanoparticles expand the space between the carbon sheets, preventing them from restacking and provide channels for the diffusion of the electrolyte and reactant. Moreover, the rich nitrogen in dicyandiamide enhances the interaction between N-doped carbon sheets and encapsulated cobalt nanoparticles, promoting the electron transfer between the electrode and reactants. As a result, dicyandiamide-regulated electrocatalyst (Co@NC-CNT) with the percentage of mesopores as high as 76.2% delivers enhanced catalytic activity toward the oxygen reduction reaction with a half-wave potential of 0.85 V in 0.1 M KOH, stably retaining 84.9% of the original current, and shows good methanol tolerance in comparison with Pt/C electrocatalysts.