Metal–organic framework derived Co3S4 nanosheets grown on Ti mesh: an efficient electrocatalyst for electrochemical sensing of hydrazine

Abstract

Constructing low cost and efficient electrochemical sensors for highly sensitive detection of hydrazine has a great significance in the field of environmental monitoring and protection. Herein, metal–organic framework derived Co₃S₄ nanosheets grown on Ti mesh (Co₃S₄/TM) were successfully synthesized by employing a facile anion exchange reaction and hydrothermal vulcanization with Co-MOF as the precursor. The crystalline structure and morphology of as-synthesized samples were characterized by XRD, SEM, Raman, XPS and TEM analysis. It was found that Co₃S₄ nanosheets were stacked loosely and irregularly on each other to form a three-dimensional (3D) porous structure. The electrochemical sensing performance of Co₃S₄/TM toward hydrazine was investigated in 0.1 M NaOH solution. The results showed that Co₃S₄/TM presented a better electrocatalytic activity toward hydrazine oxidation than Co-MOF/TM and Co(OH)₂/TM, owing to the high electrical conductivity of Co₃S₄ for enhancing electron transfer and the 3D porous structure for providing many more accessible active sites and shortening ion diffusion length as well as promoting mass transfer for hydrazine electrooxidation. As a result, Co₃S₄/TM exhibited a superior analytical performance with a wide linear range of 0.005–2.0 mM, a high sensitivity of 2956 μA mM⁻¹ cm⁻² and a low detection limit of 0.7 μM (S/N = 3), which was superior or comparable to that of the recently reported sensor. Because of the good selectivity and reproducibility, Co₃S₄/TM was applied to detection of hydrazine in tap water and it showed good recovery, indicating that it could be a promising candidate for analyzing hydrazine in practical application.