Simultaneous electrochemical sensing of dihydroxybenzene isomers at multi-walled carbon nanotubes aerogel/gold nanoparticles modified graphene screen-printed electrode

Highlights

• An electrochemical sensor was built with commercial avaliable Gr-SPE

• The Gr-SPE were modified by nafion/aerogel and AuNPs

• The obtained sensor had high sensitivity to DHB isomers.

• The method provided a universal platform for trace detection of DHB isomers

Abstract

An electrochemical sensor based on Nafion-multi-walled carbon nanotubes aerogel/gold nanoparticles modified graphene screen-printed electrode (Gr-SPE) for simultaneous electrochemical measurement of hydroquinone (HQ), catechol (CC) and resorcinol (RC) in citrate/phosphate buffer solution (CPBS, pH = 6.0) was introduced. The dihydroxybenzene (DHB) isomers could well separate from each other at the scan rate of 50 mV/s and the separations of the oxidation peak potentials of HQ-CC and for CC-RC were over more than 110 mV and 381 mV, respectively. Square wave voltammetry (SWV) was employed for the measurement of three DHB isomers in their ternary mixture. The linear response for HQ, CC and RC were 0.2-75 μM, 0.2–50 μM and 0.2–125 μM, respectively. The calculated detection limits were 0.014 μM, 0.017 μM and 0.05 μM (S/N = 3), respectively. The as-prepared sensing platform was applied to detect DHB isomers in real water samples (tap water, mineral water). The calculated recoveries were 96–100% for HQ, 95–100% for CC and 95–99% for RC, respectively.

Introduction

Dihydroxybenzene (DHB) isomers, hydroquinone (HQ), catechol (CC) and resorcinol (RC) are broadly employed in chemical production, in the pharmaceutical industry, photography, colourants, pesticides, medicines, cosmetics and so on. However, DHB compounds are greatly critical to organisms in the environmental system [1,2]. The incorporation of DHB isomers from the gastrointestinal system can stimulate some disease such as liver capacity decrease and renal pipe degeneration. Furthermore, DHBs can depress the central nervous and cardiovascular systems. Therefore, inhaling of elevated concentration of DHB can directly lead to the death of a human as well as aquatic life. DHBs are supposed to be environmental pollutants by the US Environmental Protection Agency and the European Union [[3], [4], [5]]. Due to their low degradability and special toxicity in the environmental system, and their similar chemical composition and coexistence, research has focused on developing sensible and selective techniques for the simultaneous multiplex electrochemical measurement of HQ, CC and RC. An electrochemical multi-analyte sensor for DHB isomers is becoming an exceptional and encouraging research area.

The electrochemical detections have attracted significant attention in the simultaneous determination of DHB isomers on account of many intrinsic advantages such as straightforward operation, low cost, fast response, high sensitivity, good selectivity and so on. Graphene (Gr) and carbon nanotubes (CNTs) are the most explored in the literature, due to their exceptional properties, which ensures a wide range of applications, in different areas such as sensor, electrocatalysis, separation, imaging [6]. Carbon-based nanomaterials such as Gr and CNTs are being developed and have been found to occur in functionalized and nonfunctionalized forms. Mostly Gr and CNTs can be functionalized with –OH and –COOH groups via chemical oxidation methods to produce Gr-COOH and CNTs-COOH, which are highly dispersible in water rather than in their pure form. As mentioned, Gr and CNTs can be modified with various functional groups on their surfaces via covalent and noncovalent methods for their different field applications. For sensing applications, carbon nanomaterials (Gr and CNTs) have many advantages such as small size with larger surface area, excellent electron transfer promoting ability when used as electrodes modifier in electrochemical reactions. Briefly, Gr and CNTs play an important role in the performance of electrochemical sensors [[7], [8], [9], [10], [11], [12]]. There have been many reports on carbon nanomaterials-based electrochemical sensors for determination of DHB isomers (binary (HQ and CC) and ternary (HQ, CC and RC) mixture). In this context, various nanomaterials modified electrodes including graphene/carbon nanotube hybrid nanocomposites [13,14], carbon material-supported bimetallic composites [15,16], carbon material-supported metal oxides [[17], [18], [19]], carbon material-supported conducting polymers [[20], [21], [22]] and other carbonous nanomaterials (carbon dots (CDs), carbon nanohorns (CNHs), graphene-like carbon nanosheets (Gr-CNS), carbon nanocages (CNCs) boron-doped graphene (B-Gr) and graphitic carbon nitride nanosheets (CNNS-CNTs), mesoporous carbons (MPC), carbon nanofibers (CF), carbon nano-fragments (CNF) and biochar (BC) [[23], [24], [25], [26], [27], [28], [29], [30], [31], [32], [33]] have been used to simultaneous electrochemical determination of them. Recently, we have reviewed the latest development in carbon nanomaterial-based electrochemical sensors for simultaneous detection of DHB isomers in the last five years [34]. However, to the best of our knowledge, an electrochemical sensor based on the multi-walled carbon nanotubes (MWCNTs) aerogels (AGs) for the simultaneous determination of HQ, CC and RC have not been reported so far. The multiple functional features of AGs, such as low density and high porosity, make these fascinating materials promising for a wide range of utilizations [35].

Previously studies on AG synthesis have mostly focused on sol-gel materials, silica gels, cross-linked polymers and regenerated cellulose materials. Currently, these aerogel developments have been extended to nanocarbon-based aerogels (CAGs), such as CNTs and Gr, due to their exceptional electrical and mechanical characteristics as well as high surface area. Freeze drying of GO or CNTs dispersions can also be used to generate CAGs with a high specific surface area [36,37]. In the present work, we describe the facile fabrication of CAG based on MWCNT and Nafion frameworks, referred to as Nafion-enhanced CAG (NfCAG) which were modified on the surface of the Gr-SPEs to obtain an effective sensing platform. Further, the prepared gold nanoparticles/Nafion-multi-walled carbon nanotubes aerogel/graphene screen-printed electrode AuNPs/NfCAG/Gr-SPE was employed for the simultaneous detection of DHB isomers (HQ, CC and RC).