Sustainable Route for Molecularly Thin Cellulose Nanoribbons and Derived Nitrogen-Doped Carbon Electrocatalysts

Abstract

Ultrathin cellulose nanoribbons were extracted from earth-abundant biomass using 2,2,6,6-tetramethylpiperidine-1-oxyl-catalyzed (TEMPO-catalyzed) oxidation and sonication processes. By two TEMPO-oxide systems with different processing times, TEM and AFM observations indicate the obtained cellulose nanoribbons (Cel-NRs) with dimensions of 400–800 nm in length, 1.72–2.54 nm in width, and 0.78–2.67 nm in thickness. The dimension data indicate that the Cel-NRs from the TEMPO/NaBr/NaClO system are much shorter but contain more cellulose chains than those from the TEMPO/NaClO/NaClO2 system. Moreover, these abundant biomass nanoribbons were fabricated from direct pyrolysis with NH3 activation. The obtained highly active nitrogen-doped carbon nanoribbons (N-CNRs) and metal-free oxygen reduction reaction (ORR) electrocatalysts show superb ORR activity (half-wave potential of 0.71 and 0.73 V versus reversible hydrogen electrode) and high selectivity (electron-transfer number of 3.26 and 3.74 at 0.8 V), comparable c...