Probing the Electrochemical Properties of Flower Like Mesoporous MoS₂ in Different Aqueous Electrolytes

Abstract

In the present work, flower-like mesoporous MoS₂ has been synthesized via a one step hydrothermal approach. The electrochemical performance of synthesized flower-like MoS₂ nanostructures for supercapacitor applications has been probed via cyclic voltammetry, galvanostatic charging-discharging and electrochemical impedance spectroscopy in 1 M H₂SO₄ (acidic electrolyte), 1 M Na₂SO₄ (neutral electrolyte) and 2 M KOH (basic electrolyte) electrolytes using a three electrodes configuration. On the basis of electrochemical measurements, it has been observed that as-prepared flower-like MoS₂ exhibits specific capacitances of 225 F g⁻¹, 205 F g⁻¹ and 123 F g⁻¹ in 1 M H₂SO₄, 1 M Na₂SO₄ and 2 M KOH electrolytes at 1 A g⁻¹, respectively. Moreover, for the MoS₂ electrode the diffusion coefficients in 1 M H₂SO₄, 1 M Na₂SO₄ and 2 M KOH electrolytes are found to be 8.52 × 10⁻¹⁰ cm² s⁻¹, 5.41 × 10⁻¹⁰ cm² s⁻¹ and 8.35 × 10⁻¹⁰ cm² s⁻¹, respectively. Further, the relaxation time constants (τ), which represent how quick a supercapacitor system can deliver stored energy at high power, are found to be 37 ms, 77 ms and 1.49 s for as synthesized MoS₂ in 1 M H₂SO₄, 1 M Na₂SO₄ and 2 M KOH electrolytes, respectively. However, the capacity retention/coulombic efficiency of a MoS₂ electrode in 1 M H₂SO₄, 1 M Na₂SO₄ and 2MKOH is found to be ∼ 30%/89%, 89%/94% and 86%/92%, respectively, after 1000 successive cycles at 2 A g⁻¹. Our results suggest that a pristine flower like MoS₂ is a good material to design a high performance supercapacitor device, which exhibits stable electrochemical performance in 1 M Na₂SO₄ electrolytes. The detailed electrochemical behavior of as synthesized samples has been thoroughly described in this paper. We believe our findings would be helpful in the designing of flower-like MoS₂ based practical high performance supercapacitor devices.