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.

MoS2 Decoration Followed by P Inclusion over Ni-Co Bimetallic Metal–Organic Framework-Derived Heterostructures for Water Splitting

“…Although the lower Gibbs free energy (∼Δ G H = 0.06 eV, like Pt) of MoS 2 reduces the onset potential in the HER with a very high exchange-current density, the poor electrical conductivity eventually hammers its real-time applications. Various methods have already been validated to improve the electrical conductivity without any trade-off in performance, including graphene oxide/reduced graphene oxide/carbon nanotube/graphene composites, etc. − Lately, MoS 2 based heterostructures, for instance, MoS 2 /Ni 3 S 2, display bifunctional activity toward the complete water splitting, and the interface serves as an active site …”

Insight into the Influence of Analyte Molecular Structure Targeted on MoS2-GO-Coated Electrochemical Nanosensors

“…The prominent peaks at 1328 and 1605 cm –1 in the Raman spectra of GO and MoS 2 -GO correspond to the D and G band and both of GO, respectively. For the MoS 2 -GO sample, the intensity ratio of the D band over the G band ( I D / I G ) is around 0.73, indicating the rearomatization of conjugated sp 2 networks and presence of GO in the MoS 2 -GO nanocomposite. ,, Furthermore, some well-defined peaks at 230, 378, and 407 cm –1 displayed in Raman spectra of MoS 2 -GO and MoS 2 are associated with the E 2g 1 and A 1g modes of the MoS 2 crystal. , According to these results, MoS 2 and GO were combined well together to create a composite structure with many unique features.…”

“…Many other modified electrodes based on graphene/carbon nanotubes, , gold nanoparticles, ,,, silver nanowire, polyaniline, , and molecularly imprinted film , have also been reported toward CLB and 4-NP detection. More particularly, in recent literature, MoS 2 and its combination with GO have been widely studied as high potential substances for electrode modification aiming to enhance the detectability of chemical residues. − With a large surface area, excellent conductivity, good chemical stability, and strong mechanical strength, GO promotes the accumulation of analyte molecules and long-term stability. Meanwhile, layered MoS 2 is considered a great electrocatalytic nanomaterial owing to a large number of active edge sites.…”