Highly sensitive detection of 4-NP in real water with long stability and high anti-inteference ability based on GO–Ag2CrO4/GCE

A bifunctional MoS2/SGCN nanocatalyst for the electrochemical detection and degradation of hazardous 4-nitrophenol

Herein, we reported the dual functions of molybdenum disulfide/sulfur-doped graphitic carbon nitride (MoS2/SGCN) composite as a sensing material for electrochemical detection of 4-NP and a catalyst for 4-NP degradation. The MoS2 nanosheet, sulfur-doped graphitic carbon nitride (SGCN) and MoS2/SGCN were characterized using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) spectroscopy and X-ray photoelectron spectroscopy (XPS). Electrochemical characterization of these materials with electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) in 1 mM K4[Fe(CN)6]3-/4- show that the composite has the lowest charge transfer resistance and the best electrocatalytic activity. The limit of detection (LOD) and the linear range of 4-nitrophenol at MoS2/SGCN modified glassy carbon electrode (MoS2/SGCN/GCE) were computed as 12.8 nM and 0.1 - 2.6 μM, respectively. Also, the percentage recoveries of 4-NP in spiked tap water samples ranged from 97.8 - 99.1 %. The electroanalysis of 4-NP in the presence of notable interferons shows that the proposed electrochemical sensor features outstanding selectivity toward 4-NP. Additionally, the results of the catalytic degradation of 4-NP at MoS2/SGCN show that the nanocatalyst catalyzed the transformation of 4-NP to 4-aminophenol (4-AP) with a first-order rate constant (k) estimated to be 4.2 ×10-2 s-1. The results of this study confirm that the MoS2/SGCN nanocatalyst is a useful implement for electroanalytical monitoring and catalytic degradation of the hazardous 4-NP in water samples.

Rational Design of NiCo-borate/GO Heterojunction as a High-Performance Supercapacitor Electrode

The bottleneck in the preparation of supercapacitors is how to develop high-energy and high-power-density devices by using appropriate materials. Herein, a novel NixCo3-x-B/GO heterostructure material was synthesized through a simple ultrasonic and precipitation method. The prepared NixCo3-x-B/GO heterostructure exhibits significant improvements in supercapacitor performance than NixCo3-x-B. The presence of GO effectively suppresses the excessive growth and accumulation of NixCo3-x-B; therefore, Ni2.7Co0.3-B/GO exhibits the best performance as an electrode material for supercapacitors: a high specific capacitance (Cm, 1789.72 F g-1@1 A g-1) and excellent rate performance. The asymmetric supercapacitor (ASC) device of Ni2.7Co0.3-B/GO//AC exhibits a Cm of 76.6 F g-1@1 A g-1, a large voltage window of 1.6 V, and a high energy density (ED) of 98.0 Wh kg-1. Furthermore, a flexible, all-solid-state supercapacitor assembled with Ni2.7Co0.3-B/GO as both the positive and negative electrodes demonstrates a Cm of 46.9 F g-1@1 A g-1. Even after multiple folding and bending at various angles, the device maintains excellent performance, showcasing remarkable stability. With a power density (PD) of 479.7 W kg-1, the device achieves a high ED of 60.0 Wh kg-1. This work provides valuable insights into the synergistic effects in electrochemical processes based on heterostructure materials.

Melamine functionalised multiwalled carbon nanotubes (M-MWCNTs) as a metal-free electrocatalyst for simultaneous determination of 4-nitrophenol and nitrofurantoin

An innovative melamine functionalised multiwalled carbon nanotube (M-MWCNTs) based electrochemical sensor has been developed for the determination of environmental nitro-aromatic pollutants, such as 4-nitrophenol (4-NP) and nitrofurantoin (NFT).