Enhanced energy storage capabilities of cobalt hydroxide developed with surfactants

Table of Contents


Surfactant utilisation throughout the synthesis process is crucial in defining the shape and characteristics of nanomaterials. This paper reports on the surfactant-assisted synthesis of Co(OH)2 nanoparticles and their characterisation for energy storage applications. Cobalt hydroxide nanoparticles are synthesised at 80oC utilising a chemical co-precipitation technique using hexamethylenetetramine (HMTA) as the substrate. The samples produced with and without surfactant are denoted as CHHMTA and CH, respectively. The structural, morphological, and elemental properties of the manufactured products were evaluated using scanning electron microscopy, X-ray diffraction, and FTIR methods. Cyclic voltammetry (CV) and galvanometric charge/discharge (GCD) are employed to investigate the energy storage capacity of the collected products. HMTA coated particles have better charge storage capabilities than naked Co(OH)2 nanoparticles. At 1 Ag-1 current density, the specific capacitance of CH and CHHMTA was measured to be 127 Fg-1 and 344 Fg-1, respectively.

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Experimental section


Beta cobalt hydroxide synthesis

Initially, a 50 mL aqueous solution of 200 mM Co(NO3)26H2O was created, and a dropwise addition of 10 mL aqueous solution of 0.1 M NaOH was made. The reaction mixture was left for 30 minutes with continuous vigorous stirring to generate dark green precipitate, which was then held at 80oC for 4 hours to produce pink precipitate. The precipitate was filtered and washed with DI water and anhydrous ethanol several times before being air-dried at room temperature to give cobalt hydroxide particles. HMTA coated Co(OH)2 nanoparticles (CHHMTA) were generated using a similar approach by adding 5 mM hexamethylenetetramine surfactant to the CH solution.


Materials characterization


To study phase formation, crystallinity, and crystallite size, X-ray diffraction experiments were performed using a SEM (ZEISS-GEMINI; Cu-Ka radiation k = 1.5406).Scanning electron microscopy (ZEISS-GEMINI) was used to characterise the morphology of the produced materials.To detect the functional groups present on the surface of the nanoparticles, a Fourier transform infrared spectrometer (Nicole 67000, USA) was employed.

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Electrochemical measurement


An electrochemical work station with a three-probe cell arrangement was used to record the electrochemical properties. As counter, working, and reference electrodes, platinum wire, synthesised cobalt hydroxide nanoparticles (CH and CHHMTA) coated onto Ni-foam, and Ag/AgCl were utilised. CH and CHHMTA samples were combined with N-methyle2-pyrolidone (NMP) and coated over a (0.5 1) cm2 nickel foam surface before being baked for 8 hours at 80oC in a hot air oven. The electrochemical performance of the as-prepared electrode was investigated by collecting cyclic-voltammetry (CV) and galvanometric charge/discharge data. The electrochemical characterizations were all performed with 1 M KOH as the electrolyte and a scanning speed of 50 mV/s.




Chemical co-precipitation was used to successfully create bare and hexamethylenetetramine coated cobalt hydroxide nanoparticles. The crystalline characteristics, surface morphology, and functional group present on the surface of the nanoparticles were evaluated using XRD, SEM, and FTIR methods, respectively. The electrochemical properties studied using CV and GCD tests show that cobalt hydroxide nanoparticles synthesised with HMTA as a surfactant had a higher capacitance of 344 (F/g) and a better charge/discharge behaviour than the naked Co(OH)2 sample. Our findings show that HTMA-coated Co(OH)2 nanoparticles are excellent for energy storage.




The authors are grateful to the university advanced instrumentation Centre at Babasaheb Bhimrao Ambedkar University (BBAU) for allowing them to characterise the material using XRD and FTIR. The authors would like to thank Prof. P. K. Guha for providing the CH instrument facilities for determining the CV and GCD parameters of the samples.
Read more:
  1. Jitendra Kumar, Jay Singh, Vipul Vaibhav Mishra, Chandresh Kumar Rastogi, Biswajit Mandal (2022). ‘Enhanced energy storage performance of surfactant assisted grown cobalt hydroxide.’ Materials Today: Proceedings, doi.org/10.1016/j.matpr.2022.08.034.
  2. Jay Singh, Jitendra Kumar, Chandresh Kumar Rastogi, Biswajit Mandal (2022). Surfactant assisted synthesis of Ni3V2O8 and their application as a supercapacitor’ Materials Today: Proceedings, 2022 https://doi.org/10.1016/j.matpr.2022.10.277.

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