TEMPO-mediated oxidized cellulose nanofibers-Cd2+ derived hierarchically porous carbon aerogel for oxygen reduction electrocatalysis

Abstract

• TOCNFs-Cd 2+ aerogel is constructed via the electrostatic and ionic interactions. • Cd metal acts as the thermally sacrificial template to generate ultralight N-CNA-Cd. • N -CNA-Cd has abundant micro-/meso-pores, rich defects, huge SBET and fibrous network. • An impressive ORR electrocatalytic efficacy was obtained on N-CNA-Cd sample. Carbon aerogel (CA) emerges as a kind of burgeoning material platform for electrocatalysis with merits of the 3D porous and interconnected architecture to facilitate the low-resistant mass diffusion and charge transport. There still remain great challenges in fine-tuning the intrinsic chemical nature and creating hierarchically porous microstructure in CA through a sustainable synthesis route. Here, we employed TEMPO-mediated oxidized cellulose nanofibers (TOCNFs) and a thermally sacrificial template Cd metal with low boiling point (767 °C) to assemble TOCNFs-Cd 2+ hydrogel/aerogel, which is then subsequently converted to ultralight N -doped carbon nanofibers aerogel ( N -CNA-Cd) upon pyrolysis at a moderate temperature. Thanks to the presence of abundant interior micro- and meso-pores, rich defects, huge BET specific surface area (1782 m 2 g −1 ) and interconnected fibrous network, the as-obtained N -CNA-Cd samples demonstrate an impressive electrocatalytic efficacy towards oxygen reduction reaction in terms of the positive half-wave potential (0.84 V), large electrochemical active surface area and considerable stability under both alkaline and acidic conditions. This study provides a versatile strategy for designing and engineering carbonaceous aerogels that can be suited for electrocatalysis and energy storage applications from renewable plant cellulose resources.