Microgalvanic cell-mediated green synthesis of Cu2O nanocubes with (100) facets for boosting dopamine hydrochloride sensing performance

Despite numerous efforts have been made on exploring the preparation, properties and application of Cu2O nanocrystal, there is still a lack of a facile and green synthesis strategy to obtain well-defined Cu2O nanocubes (NCs). And exploration of the superior low-index lattice plane of Cu2O in electrochemical sensing is also inadequate. Herein, we proposed a Ni(OH)2-mediated in-situ synthetic strategy for the preparation of Cu2O NCs enclosed by low-index facets with simple procedure, mild temperature and low energy-consumption. The Ni(OH)2 sites not only facilitated the contact between Cu2+ and the substrate Ni foam (NF), but also can combine with the NF to act as a primary battery to regulate the nucleation and growth rate of Cu2O (100) facets. Benefiting from the high ratio of exposed electroneutral (100) lattice planes of nanocubes, the Cu2O NCs formed on Ni(OH)2-abundant Ni Foam (Cu2O NCs/NFEO) exhibited a wide linear range (3.25-1178.8 μM), a low detection limit (1.86 μM) and a high sensitivity (900 μA mM-1 cm-2) in dopamine hydrochloride (DAH) electrochemical sensing. This work expects to provide more clues about the relationship between different dominant low-index facets of Cu2O NCs and electrochemical sensing performance towards DAH, and thereby contributes to the development of functional materials based on Cu2O nanocrystals with desirable facets.

Conformal sulfidation of HKUST-1 for constructing porous Cu2S/CuO octahedrons realizing highly sensitive non-enzymatic glucose detection

Metal-organic frameworks (MOFs) are believed to be promising precursors for constructing novel and efficient catalysts for glucose sensing. Herein, HKUST-1 precursors are first fabricated using a one-pot hydrothermal approach, and then HKUST-1 is converted into porous Cu2S/CuO octahedrons through conformal sulfidation with the help of OH-ions. The as-obtained Cu2S/CuO composite can provide rich electrochemical active sites and promoted electric transfer kinetics. Benefiting from these combined merits, the as-fabricated Cu2S/CuO composite is confirmed to be a high-performance catalyst, with high sensitivities of 8269.45 and 4140.82μA mM-1cm-2in the corresponding ranges of 0.05 ∼ 0.6 mM and 0.6 ∼ 1.2 mM, respectively. Moreover, the as-prepared electrode materials possess good anti-interference ability, reproducibility and long-term stability. This work opens up new avenues for the design and preparation of transition metal sulfide composites.

MOF-derived NiCo hydroxide for highly efficient non-enzymatic glucose biosensing

An efficient and robust electrocatalyst is significant for glucose biosensing. The emergence of metal-organic framework (MOF) derived materials opens up new avenues for the development of high-performance glucose sensing catalysts. Herein, MOF derived nickel-cobalt hydroxide supported on conductive copper sheet (NiCo-OH/Cu sheet) is prepared at room temperature. The as-obtained NiCo-OH is endowed with three-dimensional network structure which enables the effective exposure of active materials, sufficient contact between glucose molecule and catalyst. The NiCo-OH/Cu sheet is revealed as good glucose electrochemical sensing material with a wide linear range of 0.05∼6.0 mM and a high sensitivity of 1340μA mM-1cm-2. Additionally, the as-fabricated NiCo-OH/Cu sheet displays good anti-interference ability and long-term stability.

Electrochemical Characterization of Modified Glassy Carbon Electrodes for Non-Enzymatic Glucose Sensors

The diversity of materials proposed for non-enzymatic glucose detection and the lack of standardized protocols for assessing sensor performance have caused considerable confusion in the field. Therefore, methods for pre-evaluation of working electrodes, which will enable their conscious design, are currently intensively sought. Our approach involved comprehensive morphologic and structural characterization of copper sulfides as well as drop-casted suspensions based on three different polymers-cationic chitosan, anionic Nafion, and nonionic polyvinylpyrrolidone (PVP). For this purpose, scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy were applied. Subsequently, comparative studies of electrochemical properties of bare glassy carbon electrode (GCE), polymer- and copper sulfides/polymer-modified GCEs were performed using electrochemical impedance spectroscopy (EIS) and voltammetry. The results from EIS provided an explanation for the enhanced analytical performance of Cu-PVP/GCE over chitosan- and Nafion-based electrodes. Moreover, it was found that the pH of the electrolyte significantly affects the electrocatalytic behavior of copper sulfides, indicating the importance of OH_ads in the detection mechanism. Additionally, diffusion was denoted as a limiting step in the irreversible electrooxidation process that occurs in the proposed system.