Growth of vertically aligned Co3S4/CoMo2S4 ultrathin nanosheets on reduced graphene oxide as a high-performance supercapacitor electrode

Abstract

Vertically aligned Co₃S₄/CoMo₂S₄ (CMS) ultrathin nanosheets on reduced graphene oxide (rGO) are first prepared through a facile one-step hydrothermal method. Interestingly, Co₃S₄ exhibits good matching on the CoMo₂S₄ surface with semicoherent interfaces, facilitating charge transfer at the abundant CMS interfaces and guaranteeing more stable structures. Meanwhile, nanoscaled CMS sheets with ideal thicknesses of about 3–5 nm are uniformly dispersed on rGO, helping to increase the contact area with the electrolyte. These characteristics accelerate the ion transportation efficiency, and also improve the electrochemical utilization. Therefore, the hybrid shows a nice capacitance of 1457.8 F g⁻¹ at 1 A g⁻¹, and possesses good stability with 97% of the initial capacitance retained after 2000 cycles. Furthermore, an asymmetric supercapacitor device fabricated by using CMS–rGO as the positive electrode and activated carbon (AC) as the negative electrode presents a high energy density of 33.1 W h kg⁻¹ at a power density of 0.85 kW kg⁻¹ with excellent cycle stability (93.8%) even after 5000 cycles, highlighting its promising applications as an efficient electrode material for supercapacitors.