Copper–palladium alloy nanoparticle plated electrodes for the electrocatalytic determination of hydrazine

Screen-Printed Electrodes Modified with Metal Nanoparticles for Small Molecule Sensing

Recent progress in the field of electroanalysis with metal nanoparticle (NP)-based screen-printed electrodes (SPEs) is discussed, focusing on the methods employed to perform the electrode surface functionalization, and the final application achieved with different types of metallic NPs. The ink mixing approach, electrochemical deposition, and drop casting are the usual methodologies used for SPEs' modification purposes to obtain nanoparticulated sensing phases with suitable tailor-made functionalities. Among these, applications on inorganic and organic molecule sensing with several NPs of transition metals, bimetallic alloys, and metal oxides should be highlighted.

Micelles Mediated Zone Fluidics Method for Hydrazine Determination in Environmental Samples

An automated flow method for the determination of hydrazine based on the concept of zone-fluidics has been developed. The analyte reacts under flow conditions with p-dimethylamino benzaldehyde (25 mmol L-1) in micellar medium (100 mmol L-1 SDS) to form a stable derivative (460 nm). Micelles mediated catalysis excludes the use of highly acidic environment typical for this kind of reaction. Following careful examination of chemical and instrumental variables, the method allows the determination of hydrazine at the low micromolar level (0.3-10 μmol L-1) in water samples. Real sample analyses (drinking and boiler feed water) resulted in satisfactory results in terms of accuracy with the percent recoveries being in the range of 82-114%.

Observation of Single Pt Nanoparticle Collisions: Enhanced Electrocatalytic Activity on a Pd Ultramicroelectrode

Single Pt nanoparticle (NP) collisions on an electrode surface were detected by using an electrocatalytic amplification method with a Pd ultramicroelectrode (UME). Pd is not a preferred material for UMEs for the detection of single Pt NP collisions, because Pd shows similar electrocatalytic activity compared with Pt for hydrazine oxidation, thus resulting in a high background current level. However, a Pt NP colliding on the Pd UME shows greatly enhanced activity compared with a Pt NP on an inert UME, such as a Au UME, which is usually used for the detection of single Pt NP collisions. The use of an electroactive UME material instead of an inert one facilitated the study of single-NP activity on the various solid supports, which is important in many NP applications.

A 3D porous Ni-Cu alloy film for high-performance hydrazine electrooxidation

Structural design and catalyst screening are two most important factors for achieving exceptional electrocatalytic performance. Herein we demonstrate that constructing a three-dimensional (3D) porous Ni-Cu alloy film is greatly beneficial for improving the hydrazine oxidation reaction (HzOR) performance. A facile electrodeposition process is employed to synthesize a Ni-Cu alloy film with a 3D hierarchical porous structure. As an integrated electrode for HzOR, the Ni-Cu alloy film exhibits superior catalytic activity and stability to the Ni or Cu counterparts. The synthesis parameters are also systematically tuned for optimizing the HzOR performance. The excellent HzOR performance of the Ni-Cu alloy film is attributed to its high intrinsic activity, large electrochemical specific surface area, and 3D porous architecture which offers a "superaerophobic" surface to effectively remove the gas product in a small volume. It is believed that the Ni-Cu alloy film electrode has potential application in direct hydrazine fuel cells as well as other catalytic fields.

A sensitive hydrazine hydrate sensor based on a mercaptomethyl-terminated trinuclear Ni(ii) complex modified gold electrode

A mercapto-terminated trinuclear Ni(ii) complex was synthesized and used as an electrocatalyst for the detection of hydrazine hydrate.

Manganese dioxide–vulcan carbon@silver nanocomposites for the application of highly sensitive and selective hydrazine sensors

Active carbon supported MnO₂@Ag nanocomposites were developed for the highly sensitive and selective electrochemical detection of hydrazine.

Amperometric hydrogen peroxide and glucose biosensor based on NiFe2/ordered mesoporous carbon nanocomposites

Well-dispersed NiFe₂ nanoparticles homogeneously embedded in OMC display high electrochemical biosensing performance for the amperometric detection of H₂O₂ and glucose.

Au@Pd core–shell nanoparticles-decorated reduced graphene oxide: a highly sensitive and selective platform for electrochemical detection of hydrazine

An Au_core–Pd_shell-decorated reduced graphene oxide nanocomposite is successfully employed for the electrochemical detection of low-level hydrazine in an aqueous solution.

Polynuclear Nickel Hexacyanoferrate/Graphitized Mesoporous Carbon Hybrid Chemically Modified Electrode for Selective Hydrazine Detection

A hybrid polynuclear nickel hexacyanoferrate (NiHCFe)/graphitized mesoporous carbon- (GMC-) modified glassy carbon electrode (GCE/NiHCFe@GMC) has been prepared by a sequential method using electrodeposited Ni on a GMC-modified glassy carbon electrode (GCE/Ni@GMC) as a template and [Fe(CN)6]3−as anin-situchemical precipitant, without any additional interlinking agent. Physicochemical and electrochemical characterizations reveal the presence of NiHCFe units within the porous sites of the GMC. The GCE/NiHCFe@GMC electrode showed highly stable and well-defined redox behaviors with surface-confined electron-transfer mechanism in a pH 7 phosphate buffer solution. The GCE/NiHCFe@GMC showed about 20 times enhancement in hydrazine oxidation peak current along with 500 mV reduction in overpotential over the corresponding unmodified GCE/GMC. Hydrazine calibration plots by CV and amperometrici-tmethods were linear up to 1 mM and 220 μM with current sensitivity values of 15.86 μA/mM and 7.37 nA/μM, respectively. Calculated detection limit by the amperometrici-tmethod was 23.2 nM. The hybrid GCE/NiHCFe@GMC exhibits remarkable tolerance to important industrial and biological interferents. Finally determination of hydrazine in cigarette smoke sample was successfully demonstrated.

A novel glucose biosensor based on immobilization of glucose oxidase in chitosan on a glassy carbon electrode modified with gold–platinum alloy nanoparticles/multiwall carbon nanotubes

A novel glucose biosensor was constructed, based on the immobilization of glucose oxidase (GOx) with cross-linking in the matrix of biopolymer chitosan (CS) on a glassy carbon electrode (GCE), which was modified with gold-platinum alloy nanoparticles (Au-PtNPs) by electrodeposition on multiwall carbon nanotubes (CNTs) in CS film (CNTs/CS). The properties of Au-PtNPs/CNTs/CS were characterized by scan electron microscopy (SEM), X-ray diffraction (XRD), cyclic voltammetry (CV), and electrochemical impedance spectra (EIS). Primary study indicated that Au-PtNPs/CNTs had a better synergistic electrocatalytic effect on the reduction of hydrogen peroxide than did AuNPs/CNTs or PtNPs/CNTs at a low applied potential window. With GOx as a model enzyme, a new glucose biosensor was fabricated. The biosensor exhibited excellent performances for glucose at a low applied potential (0.1V) with a high sensitivity (8.53 microA mM(-1)), a low detection limit (0.2 microM), a wide linear range (0.001-7.0 mM), a fast response time (<5s), and good reproducibility, stability, and selectivity. In addition, the biosensor was applied in the determination of glucose in human blood and urine samples, and satisfied results were obtained.