Self-templated Synthesis of Nickel Silicate Hydroxide/Reduced Graphene Oxide Composite Hollow Microspheres as Highly Stable Supercapacitor Electrode Material

Nickel silicate hydroxide/reduced graphene oxide (Ni(3)Si(2)O(5)(OH)(4)/RGO) composite hollow microspheres were one-pot hydrothermally synthesized by employing graphene oxide (GO)-wrapped SiO(2) microspheres as the template and silicon source, which were prepared through sonication-assisted interfacial self-assembly of tiny GO sheets on positively charged SiO(2) substrate microspheres. The composition, morphology, structure, and phase of Ni(3)Si(2)O(5)(OH)(4)/RGO microspheres as well as their electrochemical properties were carefully studied. It was found that Ni(3)Si(2)O(5)(OH)(4)/RGO microspheres featured distinct hierarchical porous morphology with hollow architecture and a large specific surface area as high as 67.6 m(2) g(–1). When utilized as a supercapacitor electrode material, Ni(3)Si(2)O(5)(OH)(4)/RGO hollow microspheres released a maximum specific capacitance of 178.9 F g(−1) at the current density of 1 A g(−1), which was much higher than that of the contrastive bare Ni(3)Si(2)O(5)(OH)(4) hollow microspheres and bare RGO material developed in this work, displaying enhanced supercapacitive behavior. Impressively, the Ni(3)Si(2)O(5)(OH)(4)/RGO microsphere electrode exhibited outstanding rate capability and long-term cycling stability and durability with 97.6% retention of the initial capacitance after continuous charging/discharging for up to 5000 cycles at the current density of 6 A g(−1), which is superior or comparable to that of most of other reported nickel-based electrode materials, hence showing promising application potential in the energy storage area. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s11671-017-2094-9) contains supplementary material, which is available to authorized users.