Core-branched CoSe₂/Ni_0.85Se nanotube arrays on Ni foam with remarkable electrochemical performance for hybrid supercapacitors

Nanotube arrays have shown great potential in a variety of important applications, such as hybrid supercapacitors. In order to endow nanotubes with multifunctionality, rationally designed and fabricated nanotube arrays with controllable structures are highly desired, but still remain a great challenge. Herein, we report a facile synthesis strategy for core-branched CoSe₂/Ni_0.85Se nanotube arrays directly on Ni foam by simply selenizing Co-precursor nanowires for hybrid supercapacitors. This structure design could not only ensure the intimate contact of self-branched heterostructures, but also offer sufficient active sites for electrochemical reactions. Further, we propose an electrochemical activation strategy to fully boost the electrochemical performance of CoSe₂/Ni_0.85Se nanotube arrays. After electrochemical activation, CoSe₂/Ni_0.85Se nanotube arrays have been changed into porous CoOOH/NiOOH, accounting for the remarkable performance. Contributed to by short ion diffusion paths, large electroactive sites and low contact resistance, the CoSe₂/Ni_0.85Se electrode after electrochemical activation shows remarkable performance for hybrid supercapacitors.