N-doped porous carbon nanofibers fabricated by bacterial cellulose-directed templating growth of MOF crystals for efficient oxygen reduction reaction and sodium-ion storage

A nanofiber-directed templating strategy has been employed in this work to fabricate reticulated composites by decorating metal organic framework (MOF) onto a biomass scaffold of bacterial cellulose (BC). The abundant oxygen-containing groups on BC facilitate the highly dispersed nucleation of ZIF-8 (a typical MOF) and thus direct these nano-crystals assembly and growth along BC nanofibers homogeneously. The as-prepared ZIF-8@BC composites are converted into hierarchically porous carbon nanofibers with high intensity of N-dopants (N-PC@CBC) by a convenient carbonization process. In comparison with the bulk N-doping porous carbon (N-PC) by direct carbonization of pristine ZIF-8, N-PC@CBC exhibits more pronounced specific surface area and pore volume. As a result, N-PC@CBC shows outstanding oxygen reduction reaction catalytic performance approaching or even surpassing the commercial Pt/C catalyst. Additionally, the robust architecture of highly interweaved N-PC@CBC nanofibers as well as the sufficient N-dopants is also favorable for the enhancement of sodium-ion storage capability. After assembling the sodium-ion half-cells, the free-standing N-PC@CBC anodes display relatively high specific capacity, superior rate capability, and excellent cycling stability. The present work sheds light on a promising avenue to develop high-performance MOF-derived electrodes with cost-effective cellulose skeleton. (C) 2020 Elsevier Ltd. All rights reserved.