Co/CoS nanofibers with flower-like structure immobilized in carbonated porous wood as bifunctional material for high-performance supercapacitors and catalysts.

As a kind of green renewable resource from trees, wood has abundant porous structure, which makes it have great potential in the field of energy storage. However, poor conductivity and limited energy storage capacity hinder the application of wood in the field of energy storage. Here, a novel carbonization lignin-free wood (CLFW)@Co-CoS hybrid is designed and fabricated by a combination of vacuum filtration and carbonization. The CLFW@Co-CoS hybrid assembled into wood-based supercapacitor presents a high areal energy density of 610 μWh cm−2, meanwhile maintaining a high areal power density of 192 mW cm−2. There are two main reasons for the excellent capacitance characteristics: one thing is that wood has a natural and abundant porous structure, which provides more space and channels for the storage and transport of electrolyte ions. The other thing is that CoS and Co can provide high capacitance, and numerous new pores are created by the interweaving of CoS nanofibers with flower-like structure. Additionally, Co nanoparticles attached to CoS and wood have more active sites, which endows the hybrid with excellent ORR properties. Thus, this bifunctional material with excellent electrochemical performance and outstanding ORR properties has huge potential in the field of energy storage and catalysis. Unlabelled Image • Co/CoS nanofibers immobilized in carbonization wood as bifunctional hybrid for supercapacitor and electrocatalyst. • The porous wood and the pores formed by cross-linked CoS nanofibers contribute a high areal power density of 192 mW cm−2. • The high capacitance provided by Co and CoS endows wood-based composites with a high areal energy density of 610 μWh cm−2. • The hybrid shows a high oxygen reduction reaction onset potential of 0.9 V, close to commercial Pt / C. [ABSTRACT FROM AUTHOR]