Physica E 161 (2024) 115968 Available online 7 April 2024 1386-9477/© 2024 Elsevier B.V. All rights reserved. Enhancing the electrochemical performance of nickel cobalt sulfide nanostructures via molybdenum doping for supercapacitor applications Muhammad Arshad Kamran a, * , Muhammad Rashid a, 1 , Sami Ullah a, 1 , Thamer Alharbi b a Department of Physics, University of Okara, Okara, Pakistan b Department of Physics, College of Science, Majmaah University, Majmaah, 11952, Saudi Arabia A R T I C L E INFO Handling Editor: Horacio Pastawski Keywords: NiCo 2 S 4 Hydrothermal technique Energy density Electrochemical properties Energy storage ABSTRACT The electrode materials, which exhibit improved electrochemical characteristics, have broad applications in high-capacity and high-power-density storage devices like supercapacitors. This research investigates the syn- thesis, electrochemical performance, and characterization of novel nanostructures comprised of molybdenum- doped nickel cobalt sulfide (Mo-NiCo 2 S 4 NSs) as active electrode materials. For the first time, Mo-NiCo 2 S 4 nanostructures synthesized via a one-step hydrothermal method demonstrate high efficiency as supercapacitor materials, showcasing their potential for supercapacitor applications. To examine the physical and chemical characteristics of the synthesized Mo-NiCo 2 S 4 nanostructures, X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX) analyses were employed. Furthermore, the electrochemical efficacy of novel electrode materials was investigated using three electrodes configuration, aiming for superior performance in supercapacitor applications. Moreover, the collaborative effect of Mo-NiCo 2 S 4 NSs was examined via cyclic voltammogram (CV), galvanostatic charge- discharge (GCD) curves, and electrochemical impedance spectroscopy (EIS). The cotton-like modified morphology observed via SEM revealed an increase in redox-active sites, thereby enhancing the energy storage capacity of the electrode material. The optimized sample (5 % Mo-NiCo 2 S 4 NSs) demonstrated a specific capacitance of 1740 F g  1 at a current density of 4 A g  1 . Additionally, the optimized electrode displayed notable energy density (60.4 WhKg  1 ) and power density (500 Wkg -1 ). The modified cotton-like morphology of the optimized sample exhibited superior electrochemical performance compared to the NiCo 2 S 4 NSs. This study suggests that Mo-NiCo 2 S 4 nanostructures hold great promise as electrode materials for future supercapacitors in energy storage systems. 1. Introduction In the past decade, there has been increasing interest in developing new, highly efficient electrode materials for modern energy storage systems. Nowadays, researchers from numerous fields have grown interested in storing energy in different energy storage devices but supercapacitors get more attention [1–5]. There are three main types of supercapacitors (SCs) [6]: electrochemical Faradic redox reaction pseudocapacitors, electric double-layer capacitors (EDLCs), and hybrid capacitors. PCs have received a lot of interest as convenient energy-storing devices because of their remarkable power output and suitable energy density [7,8]. Supercapacitors feature a remarkably extended lifecycle, rapid charging capabilities, and superior power density, all of which are crucial for their application in digital devices, hybrid electric vehicles, and various wearable electronic gadgets [9–13]. The active material within the electrode plays a crucial function in electrochemical energy storage devices, offering surface area for redox reactions and contributing energy to the systems [14–17]. Various electrode materials, including metal oxides based materials, carbon based materials, and metal sulfides based materials, are frequently uti- lized in supercapacitors. Metal oxide-based materials and carbon-based materials encounter performance constraints, such as low energy den- sity and high production costs. However, materials based on metal sul- fides offer distinct benefits to energy storage devices owing to their increased ion diffusion rate, superior ion conductivity, and significant * Corresponding author. E-mail address: m.kamran@uo.edu.pk (M.A. Kamran). 1 These authors contribute equally to this work. Contents lists available at ScienceDirect Physica E: Low-dimensional Systems and Nanostructures journal homepage: www.elsevier.com/locate/physe https://doi.org/10.1016/j.physe.2024.115968 Received 31 January 2024; Received in revised form 24 March 2024; Accepted 3 April 2024