Tailored Yb@SrMoO₄/MoS₂ Hybrid Nanostructures: Application in High-Performance Asymmetric Supercapacitors

Abstract

A simple method for the fabrication of Yb doped SrMoO<inf>4</inf>, MoS<inf>2</inf> and Yb@SrMoO<inf>4</inf>/MoS<inf>2</inf> was developed using precipitation aided hydrothermal method. The structural, morphological and x-ray photoelectron spectroscopy (XPS) confirms the formation of nanocomposite and occurrence of mixed oxidation states. All the three materials were subjected to electrochemical studies towards supercapacitor applications in three electrode system and showed pseudocapacitor behaviour in the Yb@SrMoO<inf>4</inf>/MoS<inf>2</inf> nanocomposite. Due to the combined effect of Yb@MoO<inf>4</inf> and MoS<inf>2</inf>, Yb@SrMoO<inf>4</inf>/MoS<inf>2</inf> nanocomposites exhibited superior electrochemical activity when compared to counter parts. The specific capacitance values recorded at a scan rate of 10 mV s⁻¹ were 724, 121, and 29 F g⁻¹ for Yb@SrMoO₄/MoS₂, Yb@SrMoO₄, and MoS₂, respectively. Among these, the Yb@SrMoO₄/MoS₂ electrode demonstrated superior electrochemical performance, achieving a notable power density of 750 W kg⁻¹ and an energy density of 75.4 Wh kg⁻¹ at a current density of 0.5 A g⁻¹. Furthermore, this electrode showed commendable cycling durability, retaining 87% of its initial capacitance even after 5000 charge–discharge cycles. An asymmetric supercapacitor device (ASD) was fabricated using Yb@SrMoO₄/MoS₂ as the positive electrode and activated carbon as the negative counterpart. This configuration delivered a specific capacitance of 78 F g⁻¹ at a scan rate of 5 mV s⁻¹ and maintained 92.5% of its original capacitance during stability testing.