Bifunctional metal-organic framework-derived nitrogen-doped porous multishell CuCoS@NiCoS nanospheres for supercapacitors and hydrogen evolution reactions

Transition metal sulfide porous multishell nanostructures with high active sites have great potential for application as bifunctional materials. Herein, bifunctional metal-organic framework (MOF)-derived nitrogen-doped porous multishell CuCoS@NiCoS (N–CCS@NCS) nanospheres are synthesized on Cu–Co–O substrates. The tightly connected nanocluster particles transformed by MOFs have more active sites and surface area. The ion transport efficiency between the shell layers is improved and the resistance to ion transport is further reduced. Moreover, the porous multishell structure provides a buffer space for the shock generated by multiple rapid embedding/de-embedding of OH − ions and offered a stable structure. Interestingly, the number of shell layers, thickness, spacing, and shell density of the N–CCS@NCS nanospheres can be controlled by adjusting the Ni content. Owing to its compositional and structural advantages, the N–CCS@NCS electrode exhibited a high specific capacitance of 1259 F g −1 at 0.5 A g −1 . The assembly N–CCS@NCS//activated carbon asymmetrical supercapacitor exhibited specific energy of 87.3 W h kg −1 at 825 W kg −1 and a capacitance retention rate of 81.3 % after 8400 cycles. Furthermore, the N–CCS@NCS electrocatalyst exhibited outstanding hydrogen precipitation properties (254 mV at 10 mA cm −2 ) in 1 M KOH and excellent stability over 20 h. Therefore, MOF-derived porous multishell metal sulfides are promising candidates for supercapacitor and hydrogen evolution reaction dual applications.