One‐Step Electrodeposition of NiCo2S4 Nanosheets on Patterned Platinum Electrodes for Non‐Enzymatic Glucose Sensing

The preparation of NiCo₂S₄ (NCS) nanosheets on photolithographically patterned platinum electrodes by electrodeposition was explored. The as‐prepared nanosheets were systematically characterized by field‐emission scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, and X‐ray photoelectron spectroscopy techniques. The NCS‐modified Pt electrode was used as a non‐enzymatic glucose sensor. The sensor response exhibited two linear regions in glucose concentration, with a limit of detection of 1.2 μm . The sensors showed that the as‐prepared NCS nanosheets have excellent electrocatalytic activity towards glucose with long stability, good reproducibility, and excellent anti‐interference properties, and thus, this material holds promise for the development of a practical glucose sensor.     

Nickel Hydroxide Nanoparticle Activated Semi‐metallic TiO2 Nanotube Arrays for Non‐enzymatic Glucose Sensing

Semi‐metallic TiO₂ nanotube arrays (TiO_xC_y NTs) have been decorated uniformly with Ni(OH)₂ nanoparticles without the aid of a polymer binder. The resulting hybrid nanotube arrays exhibit excellent catalytic activity towards non‐enzymatic glucose electro‐oxidation. The anodic current density of the glucose oxidation is significantly improved compared with traditional TiO₂ nanotubes decorated with Ni(OH)₂. Moreover, the Ni(OH)₂/TiO_xC_y NT‐based electrode shows a fast response, high sensitivity, wide linear range, good selectivity and stability towards glucose electro‐oxidation, and thus provides a promising and cost‐effective sensing platform for non‐enzymatic glucose detection.     

Nanostructured Gold Microelectrodes for Non‐enzymatic Glucose Sensor

A novel, highly stable, selective, and sensitive non‐enzymatic glucose sensor was developed by simple and effective modification procedure. The modification of gold microelectrodes by electrochemically deposited gold nanoparticles resulted in increase of surface area up to 37 %. The nanostructured surfaces of the gold microelectrodes obtained by different modifications were studied by confocal microscopy, atomic force microscopy, and scanning electron microscopy. The gold nanoclusters exhibit great electrocatalytic properties toward glucose with a wide linear range from 0.5 to 50 mM, with a limit of detection 218 μM, and sensitivity of 185.2 mA mM^?1cm^?2. Moreover, the modified microelectrodes display good reproducibility, stability, and selectivity in the presence of poisoning compounds. Due to the small dimensions of gold microelectrodes and a very small volume of the sample, the microelectrodes make a contribution to miniaturisation of the system.     

NiS Hollow Spheres for High‐Performance Supercapacitors and Non‐Enzymatic Glucose Sensors

α‐NiS and β‐NiS hollow spheres were successfully synthesized via the Kirkendall effect under different hydrothermal conditions. The obtained α‐NiS and β‐NiS hollow spheres were evaluated as electrode materials for supercapacitors. Importantly, the α‐NiS hollow sphere electrode has a large specific capacitance (562.3 F g^?1 at 0.60 A g^?1) and good cycling property (maintaining about 97.5 % at 2.4 A g^?1 after 1000 cycles). Furthermore, the as‐prepared α‐NiS and β‐NiS hollow spheres were successfully applied to construct electrochemical glucose sensors. Especially, the α‐NiS hollow spheres exhibit a good sensitivity (155 μA mM^?1 cm^?2), low detection limit (0.125 μM ), and a wide linear range.     

Facile Non‐enzymatic Lactic Acid Sensor Based on Cobalt Oxide Nanostructures

In this study, we have investigated the effect of counter anions on the morphology of cobalt oxide nanostructures. The nanostructures of cobalt oxide are prepared by a low temperature aqueous chemical growth method. The morphology of cobalt oxide nanostructure material was investigated by scanning electron microscopy and the crystalline structure was studied by powder X‐ray diffraction technique. The cobalt oxide nanostructures exhibit the nanowire, lump, bundle of the nanowire and flower‐like morphologies. The XRD study has revealed a cubic phase of cobalt oxide nanostructures. The electro‐catalytic properties of cobalt oxide nanostructures were explored through cyclic voltammetry and amperometric techniques by sensing of lactic acid in the alkaline media. The cobalt oxide nanostructures prepared from cobalt nitrate have shown a well‐resolved redox peak. The proposed mechanism for the non‐enzymatic lactic acid sensor is elucidated by considering the morphology and cyclic voltammetry response. The limit of detection for the sensor was found to be 0.006 mM and it exhibits a linear range from 0.05–3 mM of lactic acid as shown by cyclic voltammetry. The amperometric response has shown the excellent current‐concentration response and the linear range of sensor was found to be 0.1 mM to 5.5 mM. The lactic acid sensor is stable, selective and can be used for practical applications. This study provides an excellent alternative analytical tool for the determination of lactic acid.     

Hierarchically Porous Nickel Oxide Nanosheets Grown on Nickel Foam Prepared by One‐Step In Situ Anodization for High‐Performance Supercapacitors

Porous NiO nanosheets are successfully grown on nickel foam substrate through an in situ anodization by using molten KOH as the electrolyte. High‐purity NiO is directly obtained by this one‐step method without any subsequent treatment. The obtained NiO supported on nickel foam is used as a binder‐free electrode for a supercapacitor and its pseudocapacitive behavior has been investigated by cyclic voltammetry and galvanostatic charge–discharge tests in a 6 M aqueous solution of KOH. Electrochemical data demonstrates that this binder‐free electrode possesses ultrahigh capacitance (4.74 F cm^?2 at 4 mA cm^?2), excellent rate capability, and cycling stability. After 1000 cycles, the areal capacitance value is 9.4 % lower than the initial value and maintains 85.4 % of the maximum capacitance value.     

Nickel Hydroxide Nanoparticles on Screen‐printed Electrodes as an Impedimetric Non‐enzymatic Glucose Sensor

In this study, the electrodeposition of nickel hydroxide nanoparticles onto a screen‐printed electrode (Ni(OH)₂/SPE) is described. Ni(OH)₂/SPE is proposed as an alternative non‐enzymatic glucose sensor based on Electrochemical Impedance Spectroscopy (EIS) measurements.The SPEs were modified by the cathodic electrodeposition of nickel, from a solution containing 0.010 M Ni(NO₃)₂ and 1 M NH₄Cl, at −1.3 V for 60 seconds. The SEM images show a uniform distribution of nickel spherical nanoparticles, with 60 nm average particle size. However, such morphology is not observed when the electrodeposition occurs in the absence of NH₄Cl. The electrochemical properties of the sensor were carefully evaluated by Cyclic Voltammetry. Ni(OH)₂/SPE shows a remarkable electrocatalytic behavior towards the oxidation of glucose in 0.1 M KOH. EIS measurements were carried out for Ni(OH)₂/SPE and a single‐frequency impedance method is proposed as transduction principle for glucose determination. The analysis of each parameter of complex impedance was performed. The best linear response was obtained for the module of impedance (|Z|) in the range of 0–2 mM of glucose at 0.1 Hz (R²=0.992) with a slope of 0.137 KΩ⁻¹⋅mM⁻¹ of glucose. Finally, Ni(OH)₂/SPE was utilized for quantification of glucose in blood samples.     

Nickel Hydroxide Supercapacitor with a Theoretical Capacitance and High Rate Capability Based on Hollow Dendritic 3D‐Nickel Current Collectors

A straightforward way to attain the theoretical capacitance and high rate capability of nickel hydroxide supercapacitors, by utilizing a mesoporous hollow dendritic three‐dimensional‐nickel (3D‐Ni) current collector is proposed. A facile electrodeposition method employing a hydrogen bubble template was chosen for rapid fabrication of the dendritic 3D‐nickel structure. After nickel hydroxide was deposited on the hollow 3D‐nickel current collector, it exhibited a highest capacitance of 3637 F g⁻¹ at a current density of 1 A g⁻¹, and retained 97 % of capacitance at a high current density of 100 A g⁻¹ with a cycle stability of over 80 % after 10 000 cycles. The enhanced performance could be attributed to the large surface area and high conductivity of the moss‐like dendritic 3D‐Ni current collector, which allowed direct contact between the active materials and the current collector, and reduced diffusion resistance between the surface of the active materials and the electrolyte. These results not only confirmed a facile fabrication method for high‐performance 3D metal nanostructures, but also offer a promising solution for state‐of‐the‐art energy storage systems.     

One‐Step SnO2 Nanotree Growth

A comparison between Au, TiO₂ and self‐catalysed growth of SnO₂ nanostructures using chemical vapour deposition is reported. TiO₂ enables growth of a nanonetwork of SnO₂, whereas self‐catalysed growth results in nanoclusters. Using Au catalyst, single‐crystalline SnO₂ nanowire trees can be grown in a one‐step process. Two types of trees are identified that differ in size, presence of a catalytic tip, and degree of branching. The growth mechanism of these nanotrees is based on branch‐splitting and self‐seeding by the catalytic tip, facilitating at least three levels of branching, namely trunk, branch and leaf.     

One‐Step Synthesis of Self‐Supported Nickel Phosphide Nanosheet Array Cathodes for Efficient Electrocatalytic Hydrogen Generation

Nickel phosphide is an emerging low‐cost, earth‐abundant catalyst that can efficiently reduce water to generate hydrogen. However, the synthesis of nickel phosphide catalysts usually involves multiple steps and is laborious. Herein, a convenient and straightforward approach to the synthesis of a three‐dimensional (3D) self‐supported biphasic Ni₅P₄‐Ni₂P nanosheet (NS) array cathode is presented, which is obtained by direct phosphorization of commercially available nickel foam using phosphorus vapor. The synthesized 3D Ni₅P₄‐Ni₂P‐NS array cathode exhibits outstanding electrocatalytic activity and long‐term durability toward the hydrogen evolution reaction (HER) in acidic medium. The fabrication procedure reported here is scalable, showing substantial promise for use in water electrolysis. More importantly, the approach can be readily extended to synthesize other self‐supported transition metal phosphide HER cathodes.     

One‐Step Synthesis and Characterization of Gold–Hollow PbSx Hybrid Nanoparticles

Turing lead into gold : Hollow hybrid PbS_x–Au nanostructures of about 10 nm in diameter were synthesized using a one‐step reaction under mild experimental conditions. The redox reaction of gold precursors with PbS nanocrystals in the presence of dodecylamine leads to the hollow feature of hybrid nanostructures (see picture).

     

Design and Application of a Non‐enzymatic Sensor Based on Metal‐organic Frameworks for the Simultaneous Determination of Carbofuran and Carbaryl in Fruits and Vegetables

A novel, stable and sensitive non‐enzymatic sensor was developed with metal‐organic frameworks (MOFs) that have attracted great attention in electrochemical sensors applications in recent years. The pore structures of MIL (Fe)‐101 and MIL (Fe)‐53 are the families of MOFs that were constructed via a simple solvothermal procedure. The 35MIL‐101(Fe)‐reduced graphene oxide nanocomposite has been used for modification of glassy carbon electrode for the determination of carbofuran (CBF) and carbaryl (CBR). The porosity of the composites increased the voltammetric responses significantly for CBF and CBR in a mixed solution that makes the simultaneous determination of both carbamate pesticides possible. Characterization of MIL (Fe)‐101 and MIL (Fe)‐53 were performed with FT‐IR, XRD, BET and SEM. Finally, the introduced sensor under the optimal conditions showed low detection limits of 1.2 and 0.5 nM within the linear ranges of 5.0–200.0 nM and 1.0–300.0 nM for CBF and CBR, respectively. The non‐enzymatic sensor was successfully used to monitoring of carbamates residue in vegetable and fruit samples.     

Fabrication of Non‐enzymatic Electrochemical Glucose Sensor Based on Pd−Mn Alloy Nanoparticles Supported on Reduced Graphene Oxide

Mixed metals alloy nanoparticles supported on carbon nanomaterial are the most attractive candidates for the fabrication of non‐enzymatic electrochemical sensor with enhanced electrochemical performance. In this study, palladium‐manganese alloy nanoparticles supported on reduced graphene oxide (Pd?Mn/rGO) are prepared by a simple reduction protocol. Further, a novel enzyme‐free glucose sensing platform is established based on Pd?Mn/rGO. The successful fabrication of Pd?Mn alloy nanoparticles and their attachment at rGO are thoroughly characterized by various microscopic and spectroscopic techniques such as XRD, Raman, TEM and XPS. The electrochemical activity and sensing features of designed material towards glucose detection are explored by amperometric measurments in 0.1 M NaOH at the working voltage of ?0.1 V. Thanks to the newly designed Pd?Mn/rGO nanohybrid for their superior electrorochemical activity towards glucose comprising the admirable sensing features in terms of targeted selectivity, senstivity, two linear parts and good stability. The enhanced electrochemical efficacy of Pd?Mn/rGO electrocatalyst may be credited to the abundant elecrocatalytic active sites formed during the Pd?Mn alloying and the electron transport ability of rGO that augment the electron shuttling phenomenon between the electrode material and targeted analyte.     

Non‐enzymatic Fructose Sensor Based on Co3O4 Thin Film

In this study, we report on the selective of fructose on Co₃O₄ thin film electrode surface. A facile chemical solution deposition technique was used to fabricate Co₃O₄ thin film on fluorine doped tin oxide, FTO, glass. Electrode characterization was done using XRD, HRTEM, SEM, AFM, and EIS. The constructed sensor exhibited two distinctive linear ranges (0.021–1.74 mM; 1.74–∼15 mM) covering a wide linear range of up to ∼15 mM at an applied potential of +0.6 V vs Ag/AgCl in 0.1 M NaOH solution. The sensor demonstrated high, reproducible and repeatable (R.S.D of <5 %) sensitivity of 495 (lower concentration range) & 53 (higher concentration range) μA cm⁻² mM⁻¹. The sensor produced a low detection limit of ∼1.7 μM (S/N =3). The electrode was characterised by a fast response time of <6 s and long term stability. The repeatability and stability of the electrode resulted from the chemical stability of Co₃O₄ thin film. The sensor was highly selective towards fructose compared to the presence of other key interferences i. e. AA, AC, UA. The ease of the electrode fabrication coupled with good electrochemical activity makes Co₃O₄ thin film, a promising candidate for non‐enzymatic fructose detection.     

A Non‐Enzymatic Hydrogen Peroxide Sensor Based on Ag/MnOOH Nanocomposites

A novel non‐enzymatic sensor based on Ag/MnOOH nanocomposites was developed for the detection of hydrogen peroxide (H₂O₂). The H₂O₂ sensor was fabricated by immobilizing Ag/MnOOH nanocomposites on a glassy carbon electrode (GCE). The morphology and composition of the sensor surface were characterized using scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, transmission electron microscopy and X‐ray diffraction spectroscopy. The electrochemical investigation of the sensor indicates that it possesses an excellent electrocatalytic property for H₂O₂, and could detect H₂O₂ in a linear range from 5.0 µM to 12.8 mM with a detection limit of 1.5 µM at a signal‐to‐noise ratio of 3, a response time of 2 s and a sensitivity of 32.57 µA mM^?1 cm^?2. Additionally, the sensor exhibits good anti‐interference. The good analytical performance, low cost and straightforward preparation method made this novel electrode material promising for the development of effective non‐enzymatic H₂O₂ sensor.     

Solution‐Based Synthesis of Layered Intergrowth Compounds of the Homologous PbmBi2nTe3n+m Series as Nanosheets

Layered intergrowth compounds in the homologous Pb_mBi_2nTe_3n+m family are interesting because they are examples of natural heterostructures. We present a simple solution‐based synthesis of two‐dimensional nanosheets of PbBi₂Te₄, Pb₂Bi₂Te₅, and PbBi₆Te₁₀ layered intergrowth compounds, which are members of the Pb_mBi_2nTe_3n+m [that is, (PbTe)_m(Bi₂Te₃)_n] homologous series. Few‐layer nanosheets exhibit narrow optical band gaps (0.25–0.7 eV) with semiconducting electronic‐transport properties.     

Multianalyte Electrochemical Biosensor Based on Aptamer‐ and Nanoparticle‐Integrated Bio‐Barcode Amplification

In the present work, a signal‐on electrochemical sensing strategy for the simultaneous detection of adenosine and thrombin is developed based on switching structures of aptamers. An Au electrode as the sensing surface is modified with two kinds of thiolated capture probes complementary to the linker DNA that contains either an adenosine aptamer or thrombin aptamer. The capture probes hybridize with their corresponding linker DNA, which has prehybridized with the reporter DNA loaded onto the gold nanoparticles (AuNPs). The AuNP contained two kinds of bio‐barcode DNA: one is complementary to the linker DNA (reporter), whereas the other is not (signal) and is tagged with different metal sulfide nanoparticles. Thus a “sandwich‐type” sensing interface is fabricated for adenosine and thrombin. With the introduction of adenosine and thrombin, the aptamer parts bind with their targets and fold to form the complex structures. As a result, the bio‐barcoded AuNPs are released into solution. The metal sulfide nanoparticles are measured by anodic stripping voltammetry (ASV), and the concentrations of adenosine and thrombin are proportional to the signal of either metal ion. With the dual amplification of the bio‐barcoded AuNP and the preconcentration of metal ions through ASV technology, detection limits as low as 6.6×10^?12 M for adenosine and 1.0×10^?12 M for thrombin are achieved. The sensor exhibits excellent selectivity and detectability in biological samples.     

Thermal‐Induced Formation of a Three‐Dimensional Nanoplasmonic Sensor from Ag Nanocubes with High Stability and Reusability

Nanoplasmonic sensors based on the localized surface plasmon resonance (LSPR) of noble metal nanoparticles have many advantages, such as real‐time detection, no need for reagent labelling, and no use of complicated equipment. However, the nanoplasmonic sensors with two dimensional structures usually suffer from a low LSPR signal and thus low sensitivity due to the low density of the nanoparticles. In addition, complicated surface functionalization is always required to suppress the non‐specific binding of the analyst to the substrate of the sensor, because the two types of surface, that is, metal and substrate surfaces, are simultaneously exposed to the reaction medium. To overcome these problems, an innovative thermal‐induced method has been proposed in the present work, to construct three dimensional (3D) nanostructure of Ag nanocubes on both surfaces of the substrate by using the unique amphiphilic property of 2‐diethylaminoethanethiol. The prepared nanoplasmonic sensor is highly sensitive due to the high density of 3D structure of the nanoparticles and the low non‐specific binding since only one type of surface is exposed. To enhance the stability of the sensor, a thin SiO₂ overlayer was formed on the surface without using an additional coupling agent. Furthermore, the Ni^II‐nitriloacetic acid (Ni^II‐NTA) complex was covalently bound on the surface, so that the regeneration and reuse of the sensor becomes easy. Therefore, the easy fabrication, high stability, and good reusability of this 3D LSPR sensor makes our method competitive for the development of nanoplasmonic sensors.     

One‐Pot Template‐Free Synthesis of Monodisperse Zinc Sulfide Hollow Spheres and Their Photocatalytic Properties

Little hollow! Monodisperse ZnS hollow nanospheres (see figure) of about 200 nm in size have been fabricated on a large scale by a hydrothermal method and they show good photocatalytic activity in the decolorization of an aqueous solution of rhodamine B under UV irradiation.

     

Graphene–CdS Nanocomposites: Facile One‐Step Synthesis and Enhanced Photoelectrochemical Cytosensing

Graphene–CdS (GR–CdS) nanocomposites were prepared in a one‐step synthesis in aqueous solution. The synthetic approach was simple and fast, and it may be extended for the synthesis of other GR–metal‐sulfide nanocomposites. The as‐prepared GR–CdS nanocomposite films inherited the excellent electron‐transport properties of GR. In addition, the heteronanostructure of the GR–CdS nanocomposites facilitated the spatial separation of the charge carriers, thus resulting in enhanced photocurrent intensity, which makes it a promising candidate for photoelectrochemical applications. This strategy was used for the fabrication of an advanced photoelectrochemical cytosensor, based on these GR–CdS nanocomposites, by using a layer‐by‐layer assembly process. This photoelectrochemical cytosensor showed a good photoelectronic effect and cell‐capture ability, and had a wide linear range and low detection limit for Hela cells. The as‐synthesized GR–CdS nanocomposites exhibited obviously enhanced photovoltaic properties, which could be an efficient platform for many other high‐performance photovoltaic devices.