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

摘要

Nickel silicate hydroxide/reduced graphene oxide (Ni3Si2O5(OH)4/RGO) composite hollow microspheres were one-pot hydrothermally synthesized by employing graphene oxide (GO)-wrapped SiO2 microspheres as the template and silicon source, which were prepared through sonication-assisted interfacial self-assembly of tiny GO sheets on positively charged SiO2 substrate microspheres. The composition, morphology, structure, and phase of Ni3Si2O5(OH)4/RGO microspheres as well as their electrochemical properties were carefully studied. It was found that Ni3Si2O5(OH)4/RGO microspheres featured distinct hierarchical porous morphology with hollow architecture and a large specific surface area as high as 67.6 m² g^–1. When utilized as a supercapacitor electrode material, Ni3Si2O₅(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 Ni₃Si₂O₅(OH)₄ hollow microspheres and bare RGO material developed in this work, displaying enhanced supercapacitive behavior. Impressively, the Ni₃Si₂O₅(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 materialThe online version of this article (doi:10.1186/s11671-017-2094-9) contains supplementary material, which is available to authorized users.