NiMoO4 nanosheet arrays anchored on carbon cloth as 3D open electrode for enzyme-free glucose sensing with improved electrocatalytic activity

Tailoring the d-band center on Ru1Cu single-atom alloy nanotubes for boosting electrochemical non-enzymatic glucose sensing

The development of cost-effective and highly efficient electrocatalysts is critical to help electrochemical non-enzymatic sensors achieve high performance. Here, a new class of catalyst, Ru single atoms confined on Cu nanotubes as a single-atom alloy (Ru1Cu NTs), with a unique electronic structure and property, was developed to construct a novel electrochemical non-enzymatic glucose sensor for the first time. The Ru1Cu NTs with a diameter of about 24.0 nm showed a much lower oxidation potential (0.38 V) and 9.0-fold higher response (66.5 μA) current than Cu nanowires (Cu NWs, oxidation potential 0.47 V and current 7.4 μA) for glucose electrocatalysis. Moreover, as an electrochemical non-enzymatic glucose sensor, Ru1Cu NTs not only exhibited twofold higher sensitivity (54.9 μA mM-1 cm-2) and wider linear range (0.5-8 mM) than Cu NWs, but also showed a low detection limit (5.0 μM), excellent selectivity, and great stability. According to theoretical calculation results, the outstanding catalytic and sensing performance of Ru1Cu NTs could be ascribed to the upshift of the d-band center that helped promote glucose adsorption. This work presents a new avenue for developing highly active catalysts for electrochemical non-enzymatic sensors.

Microplasma and quenching-induced Co doped NiMoO4 nanorods with oxygen vacancies for electrochemical determination of glucose in food and serum

In this paper, Co-doped NiMoO₄ nanorods with oxygen vacancies are synthesized on carbon cloth (Co-NiMoO₄ NRs/CC) via microplasma and quenching-induced method.Owing to the surface defects and metal ion doping, the electronic structure and surface properties of the catalyst are tuned.Cyclic voltammetry (CV) and amperometry are used to investigate the electrocatalytic behavior of the glucose sensor in an alkaline medium with sensitivities of 7411 and 3125 μA L mmol^-1 cm^-2 in the linear range 1.0 μmol L^-1 to 1.0 mmol L^-1 and 1.0 mmol L^-1 to 7.0 mmol L^-1, respectively. The detection limit is 0.079 μmol L^-1 at S/N = 3. Moreover, the as-prepared catalyst electrode is also successfully used in real food and serum samples, with a recovery rate of 97.1%-107.4%.The DFT calculations show that the Co site of the catalyst significantly influenced glucose sensing performance. This idea expands the application of quenching chemistry in electrochemical sensing.

Direct epitaxial growth of nickel phosphide nanosheets on nickel foam as self-support electrode for efficient non-enzymatic glucose sensing

Design and develop of cost-effective non-enzymatic electrode materials is of great importance for next generation of glucose sensors. In this work, we report a high-performance self-supporting electrode fabricated via direct epitaxial growth of nickel phosphide on Ni foam (Ni₂P/NF) for nonenzymatic glucose sensors in alkaline solution. Under the optimal conditions, the uniform Ni₂P nanosheets could be obtained with an average thickness of 80 nm, which provides sufficient active sites for glucose molecules. As a consequence, the Ni₂P/NF electrode displays superior electrochemistry performances with a high sensitivity of 6375.1μA mM^-1cm^-2, a quick response about 1 s, a low detection limit of 0.14μM (S/N = 3), and good selectivity and specificity. Benefit from the strong interaction between Ni₂P and NF, the Ni₂P/NF electrode is also highly stable for long-term applications. Furthermore, the Ni₂P/NF electrode is capable of analyzing glucose in human blood serum with satisfactory results, indicating that the Ni₂P/NF is a potential candidate for glucose sensing in real life.

Construction of an MnO2 nanosheet array 3D integrated electrode for sensitive enzyme-free glucose sensing

MnO₂ based electrochemical enzyme-free glucose sensors remain significantly limited by their low electronic conductivity and associated complex preparation. In this paper, an MnO₂ nanosheet array supported on nickel foam (MnO₂ NS/NF) was prepared using a simple hydrothermal synthesis and employed as a 3D integrated electrode for enzyme-free glucose detection. It was found that MnO₂ NS/NF shows high performance with a wide linear range from 1 μM to 1.13 mM, a high sensitivity of 6.45 mA mM^-1 cm^-2, and a low detection limit of 0.5 μM (S/N = 3). Besides, MnO₂ NS/NF shows high selectivity against common interferences and good reliability for glucose detection in human serum. This work demonstrates the promising role of MnO₂ NS/NF as an efficient integrated electrode in enzyme-free glucose detection with high performance.

Facile synthesis of CuCo2O4@NiCo2O4 hybrid nanowire arrays on carbon cloth for a multicomponent non-enzymatic glucose sensor

The design of hierarchical heterogeneous structures with rational components is considered as a promising method to enhance the properties of electrocatalyst. Binary metal oxides, with high electrochemical activity, have attracted considerable interest in glucose determination. In this work, we synthesized the CuCo₂O₄@NiCo₂O₄ hybrid structure on conductive carbon cloth (CC) via a simple two-step hydrothermal process and investigated its catalytic ability toward glucose. The two individual components that make up this hybrid electrode have good electrical conductivity and excellent catalytic properties for glucose, so the smart combination of these two active materials can provide more catalytic sites and sufficient redox couples for the glucose oxidation. As a result, the CuCo₂O₄@NiCo₂O₄ modified CC presented superior glucose sensing properties, including ultrahigh sensitivity, fast response time, wide linear range and acceptable detection limit. Besides, the sample also exhibited good selectivity for substances in human blood that interfere with glucose detection, such as UA, AA, fructose, sucrose and KCl. The potential of the CuCo₂O₄@NiCo₂O₄/CC electrode for practical application was investigated by measuring the glucose concentration in real serum samples. These results prove that the construction of hierarchical ordered structure is conducive to the improvement of glucose sensor.

Facile preparation of novel Pd nanowire networks on a polyaniline hydrogel for sensitive determination of glucose

In this study, novel Pd nanowire networks (PdNW) grown on three-dimensional polyaniline hydrogel (3D-PANI) were prepared via a facile one-step electrodeposition approach at a constant potential of - 0.2 V and further utilized as an electrochemical sensing material for sensitive determination of glucose in alkaline medium. Compared with the sensor based on Pd nanofilm (PdNF)/3D-PANI prepared by electrodeposition at - 0.9 V, the sensor based on PdNW/3D-PANI presented substantially enhanced electrocatalytic activity towards glucose oxidation, with an excellent sensitivity of 146.6 μA mM^-1 cm^-2, a linear range from 5.0 to 9800 μM, and a low detection limit of 0.7 μM and was, therefore, demonstrated to be available for the determination of glucose in human serum. These findings are likely attributed to the combination of advantages of both PdNW and 3D-PANI, which outperformed most other Pd-based non-enzymatic glucose sensors reported earlier. Moreover, this non-enzymatic electrochemical sensor based on PdNW/3D-PANI may serve as an alternative tool for the assay of glucose and possibly other biomolecules. Graphical abstract.

Hierarchical core-shell structured Ni3S2/NiMoO4 nanowires: a high-performance and reusable electrochemical sensor for glucose detection

Designing highly active electrode is important for the fabrication of electrochemical sensing platforms, and core-shell nanostructures with large specific surface areas and ease of accessibility are effective probes for the detection of biomolecules. In this work, we report the development of hierarchical core-shell Ni3S2/NiMoO4 nanowires on a nickel foam substrate (Ni-Ni3S2/NiMoO4) as a non-noble metal catalyst electrode for the electrochemical oxidation of glucose in alkaline electrolyte. As an electrochemical sensor for glucose detection, the fabricated hierarchical Ni-Ni3S2/NiMoO4 core-shell nanowires display an enhanced catalytic response, a fast response time of 1 s with a limit of detection (LOD) of 0.055 μM (S/N = 3), and a higher sensitivity of 10.49 μA μM-1 cm-2. Unlike Ni3S2 or NiMoO4 electrodes, the observed superior catalytic activity towards glucose is mainly due to the promotional effect of NiMoO4 nanosheets on the Ni3S2 nanowires, which can increase the large active surface area and generate numerous active sites within and on the surface walls of the nanowire structures. The developed Ni-Ni3S2/NiMoO4 nanowire electrode can selectively detect glucose in the presence of other carbohydrates, such as fructose, sucrose, lactose, maltose, galactose, mannose, and xylose, indicating potential anti-interference properties. The Ni-Ni3S2/NiMoO4 nanowire electrode is highly stable for reuse and its practical application is demonstrated using real blood serum samples. These results demonstrate that hierarchical core-shell Ni3S2/NiMoO4 nanowires show potential for application in the development of low-cost applied glucose sensors.

A novel method to construct a 3D FeWO4 microsphere-array electrode as a non-enzymatic glucose sensor

As the special sensor for glucose detection, a non-noble-metal nanoarray architecture is extremely attractive due to its easy accessibility to target molecules and more exposed surface area. In this communication, we report the first synthesis of FeWO₄ microsphere-array on the three-dimensional (3D) Ni foam (FeWO₄ microspheres/NF) as the mimetic electrode for efficient catalytic oxidation of glucose in an alkaline medium. When used as an artificial analog glucose sensor, the result of the present sensing system can also be calculated with a sensitivity of 2810 μA mM cm^-2, a linear range from 0.04 mM to 2 mM and a detection limit up to 1.4 μM (S/N = 3). This glucose sensor with satisfactory stability and reproducibility can also be applied to the detection of glucose in human serum. As a promising sensing platform, this proposed 3D FeWO₄ microspheres/NF may open a new strategy for pursuing electrochemical detection of biomolecules.

High-performance electrochemical nitrite sensing enabled using commercial carbon fiber cloth

Exceptional high-performance and stable electrochemical nitrite sensing enabled using commercial carbon fiber cloth.