N, S dual doped mesoporous carbon assisted simultaneous electrochemical assay of emerging water contaminant hydroquinone and catechol

Heteroatom doped mesoporous carbon materials are promising catalysts for the electrochemical sensing application. Herein, we report highly efficient dual heteroatom-doped hexagonal mesoporous carbon (MC) derived from Santa Barbara Amorphous-15 (SBA-15) hard template for the detection of phenolic isomers. The synthesis involves dopamine hydrochloride (DA)/thiophene complex, which helps to attain perfectly retained N and S dual doped mesoporous carbon (NS-MC) framework. NS-MC exhibits higher surface area (951 m² g^-1) as well as higher pore volume (0.12 cm³ g^-1) with huge graphitic, pyridinic and thiophenic defective sites which facilitates the well-resolved simultaneous electrochemical detection of phenolic isomers hydroquinone (HQ) and catechol (CC). Our results demonstrate that as-synthesized NS-MC material had a LOD of 0.63 μM and 0.29 μM for HQ and CC, respectively. From the calibration curve, sensitivities of proposed sensor were found to be 9.44, 2.71 μA μM^-1 cm^-2 and 20.80, 10.02 μA μM^-1 cm^-2 for HQ and CC, respectively with good linear ranges of 10-45 μM and 45-115 μM for HQ; 2-16 μM and 16-40 μM for CC. The NS-MC modified electrode exhibited good selectivity over various possible interferences. The present investigation reveals that the proposed NS-MC material is a promising metal-free catalyst which boosted to electrochemically detect both HQ and CC, present in the municipal tap as well as natural river stream water samples.

Sensitive and direct electrochemical detection of bisphenol S based on 1T&2H-MoS2/CNTs-NH2 nanocomposites

A voltammetric sensor was constructed for ultra-trace BPS detection based on the signal amplification effect of 1T&2H-MoS2 and CNTs-NH2 composites.

Facile Pretreatment of Three-Dimensional Graphene through Electrochemical Polarization for Improved Electrocatalytic Performance and Simultaneous Electrochemical Detection of Catechol and Hydroquinone

Three-dimensional graphene (3DG) with macroporous structure has great potential in the field of electroanalysis owing to a large active area, excellent electron mobility and good mass transfer. However, simple and low-cost preparation of 3DG electrodes with high electrocatalytic ability is still a challenge. Here, a fast and convenient electrochemical polarization method is established to pretreat free-standing 3DG (p-3DG) to offer high electrocatalytic ability. 3DG with monolithic and macroporous structure prepared by chemical vapor deposition (CVD) is applied as the starting electrode. Electrochemical polarization is performed using electrochemical oxidation (anodization) at high potential (+6 V) followed with electrochemical reduction (cathodization) at low potential (-1 V), leading to exposure of edge of graphene and introduction of oxygen-containing groups. The as-prepared p-3DG displays increased hydrophilicity and improved electrocatalytic ability. As a proof of concept, p-3DG was used to selective electrochemical detection of two isomers of benzenediol, hydroquinone (p-BD) and catechol (o-BD). In comparison with initial 3DG, p-3DG exhibits increased reversibility of redox reaction, improved peak current and good potential resolution with high potential separation between p-BD and o-BD. Individual or selective determination of p-BD or o-BD in single substance solution or binary mixed solution is realized. Real analysis of pond water is also achieved.