MoS2 Nanosheets Decorated Multi-walled Carbon Nanotube Composite Electrocatalyst for 4-Nitrophenol Detection and Hydrogen Evolution Reaction

Abstract

Various kinds of electrocatalysts have been widely investigated for the reduction of organic pollutants and the production of clean energy resources. Therefore, cost-effective and stable electrocatalysts are need of the hour. Herein, we synthesized molybdenum disulfide (MoS2) decorated multi-walled carbon nanotubes (MWCNTs) composite using a hydrothermal method for efficient hydrogen production and electrochemical detection of 4-nitrophenol (4-NP). X-ray diffraction and Raman analysis confirmed the successful formation of the MWCNTs/MoS2 composite. SEM images showed that the pristine MoS2 exhibited a flower-like morphology with an average particle diameter of 3 μm. Transmission electron microscopy proved that the MoS2 nanosheets were decorated on the MWCNTs surface. The composite showed good performance in terms of electrochemical reduction of 4-NP in 0.1 M phosphate buffer (pH 7.0). The linear sweep voltammetric response of the composite electrode for sensing of 4-NP exhibited a linear relation with the concentration range of 0.75–71 μM and a low detection limit of 0.47 μM. The composite electrode showed high sensitivity (1.67 μA/μM/cm2), good stability, and excellent selectivity. The MWCNTs/MoS2 composite exhibited superior electrocatalytic activity in the hydrogen evolution reaction relative to the MoS2 catalyst. The composite coated carbon cloth showed a low overpotential of 211 mV for hydrogen evolution in 0.5 M H2SO4. The electrocatalyst split water into hydrogen up to 22 h with a Tafel slope of 136 mV/dec.