Binderless Solution Processed Zn Doped Co3O4 Film on FTO for Rapid and Selective Non‐enzymatic Glucose Detection

A simple solution based deposition process has been used to fabricate Zn doped Co₃O₄ electrode as an electrocatalyst for non‐enzymatic oxidation of glucose. XRD, HRTEM, SEM, EELS, AFM, EIS was used to characterise the electrode. The addition of Zn as dopant on Co₃O₄ resulted in enhanced electrochemical performance of Zn:Co₃O₄ material compared to pristine Co₃O₄ due to increased charge transferability. The as prepared electrode showed fast response (<7 s) time, good sensitivity (193 μA mM⁻¹ cm⁻²) in the linear range of 5 μM–0.62 mM, good selectivity towards glucose at a relatively lower applied potential of +0.52 V in 0.1 M NaOH solution. A detection limit of ∼2 μM was measured for the Zn:Co₃O₄ electrode. The applied fabrication method resulted in good inter and intra electrode reproducibility as was shown by the lower relative standard deviation values (R.S.D). The electrode retained 70 % of initial current response after 30 days. Although the as prepared Zn:Co₃O₄ electrodes did not result in highest reported sensitivity, and lowest limit of detection; the ease of fabrication and scalability of production, good inter and intra electrode reproducibility makes it a potential candidate for commercial application as glucose sensor.     

MOF‐Derived Spinel NiCo2O4 Hollow Nanocages for the Construction of Non‐enzymatic Electrochemical Glucose Sensor

Non‐enzymatic glucose sensor is greatly expected to take over its enzymatic counterpart in the future. In this paper, we reported on a facile strategy to construct a non‐enzymatic glucose sensor by use of NiCo₂O₄ hollow nanocages (NiCo₂O₄ HNCs) as catalyst, which was derived from Co‐based zeolite imidazole frame (ZIF‐67). The NiCo₂O₄ HNCs modified glassy carbon electrode (NiCo₂O₄ HNCs/GCE), the key component of the glucose sensor, showed highly electrochemical catalytic activity towards the oxidation of glucose in alkaline media. As a result, the proposed non‐enzymatic glucose sensor afforded excellent analytical performances assessed with the aid of cyclic voltammetry and amperometry (i–t). A wide linear range spanning from 0.18 μΜ to 5.1 mM was achieved at the NiCo₂O₄ HNCs/GCE with a high sensitivity of 1306 μA mM^?1 cm^?2 and a fast response time of 1 s. The calculated limit of detection (LOD) of the sensor was as low as 27 nM (S/N=3). Furthermore, it was demonstrated that the non‐enzymatic glucose sensor showed considerable anti‐interference ability and excellent stability. The practical application of the sensor was also evaluated by determination of glucose levels in real serum samples.     

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.     

Novel Sn Doped Co3O4 Thin Film for Nonenzymatic Glucose Bio‐Sensor and Fuel Cell

A facile chemical solution deposition via two‐step spin coating technique was used to fabricate nano‐particulate novel Sn doped Co₃O₄ thin film for glucose sensor and fuel cell applications. Substitution of Sn into Co₃O₄ host lattice lead to a remarkable increase in the electrocatalytic activity of the Co₃O₄ electrode material. Film thickness played a significant role in enhancing the charge transferability of the electrode as was observed from electrochemical impedance spectroscopy (EIS). The best sensor exhibited two wide linear response ranges (2 μM up to ∼0.5 mM and 0.6 mM up to ∼5.5 mM respectively) with sensitivities of 921 and 265 μA cm⁻² mM⁻¹ respectively and low limit of detection of 100 nM (S/N=3). The sensor was very selective towards glucose in the presence of various interference and showed long term stability. Moreover, the developed thin film modified electrode could generate one electron current in nonenzymatic fuel cell setup at room temperature.     

α‐Fe2O3 Film with Highly Photoactivity for Non‐enzymatic Photoelectrochemical Detection of Glucose

A non‐enzyme photoelectrochemical (PEC) glucose sensor based on α‐Fe₂O₃ film is investigated. The α‐Fe₂O₃ film was fabricated via a simple spin coating method. The proposed glucose sensor exhibits good selectivity, a fast response time of <5 s, a linear range of 0.05 to 6.0 mM, sensitivity of 17.23 μA mM^?1 cm^?2 and a detection limit of 0.05 μM. Meanwhile, the excellent performances of the α‐Fe₂O₃ sensor were obtained in reproducibility and the long‐term stability under ambient condition. The linear amperometric response of the sensor covers the glucose levels in physiological and clinical for diabetic patients. Therefore, this non‐enzyme PEC sensor based on α‐Fe₂O₃ film has a great potential application in the development of glucose sensors.     

Studies of Nano－sized Co304 as Anode Materials for Lithium－ion Batteries

The structural evolution of the Co₃O₄ fine powders prepared by rheological phase reaction and pyrolysis method upon different temperature has been investigated using X‐ray diffraction (XRD) topography. The electrochemical performance of Co₃O₄ electrode materials for Li‐ion batteries is studied in the form of Li/Co₃O₄ cells. The reversible capacity as high as 930 mAh/g for the Co₃O₄ sample heat‐treated at 600 °C is achieved and sustained over 30 times charge‐discharge cycles at room temperature. The detailed information concerning the reaction mechanism of Co₃O₄ active material together with lithium ion is obtained through ex‐situ XRD topography, X‐ray photoelectron spectroscopy (XPS) analysis and cyclic voltammetry (CV) technique. And it is revealed that a “two‐step” reaction is involved in the charge and discharge of the Li/Co₃O₄ cells, in which Co₃O₄ active material is reversibly reduced into xCoO(3 ‐ x)CoO and then into metallic Co.     

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.     

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.     

Gas Sensing Properties of Co3O4-loaded SnO2 to Ethanol and Acetone

A series of Co3O4-loaded SnO2 nanocomposite thick films were prepared by grinding, screen-printing and sintering at 700 ±C for 3 h. XRD data showed the nanocomposite thick films were rutile structure of SnO2 and cubic Co3O4. The composite films were found to exhibit good response to alcohol and acetone at 300 ±C. The film went through a sharp sensitivity maximum at 5 mol%CoO4=3 with a change in Co3O4 content. At 300 ±C, the maximum sensor response to alcohol and acetone, each 1000 ppm in air, was 301 and 235, respectively, which was about 7 and 5 times as large as that of the pure SnO2 respectively. The selectivity to alcohol and acetone over H2 and CO also was promoted by the addition of Co3O4 to SnO2. The mechanism of such strong promotion of sensor response (electronic sensitization) is discussed.     

Pure and Palladium‐Loaded Co3O4 Hollow Hierarchical Nanostructures with Giant and Ultraselective Chemiresistivity to Xylene and Toluene

Pure and palladium‐loaded Co₃O₄ hollow hierarchical nanostructures consisting of nanosheets have been prepared by solvothermal self‐assembly. The nanostructures exhibited an ultrahigh response and selectivity towards p‐xylene and toluene. The responses (resistance ratio) of the palladium‐loaded Co₃O₄ hollow hierarchical nanostructures to 5 ppm of p‐xylene and toluene were as high as 361 and 305, respectively, whereas the selectivity values (response ratios) towards p‐xylene and toluene over interference from ethanol were 18.1 and 16.1, respectively. We attributed the giant response and unprecedented high selectivity towards methylbenzenes to the abundant adsorption of oxygen by Co₃O₄, the high chemiresistive variation in the Co₃O₄ nanosheets (thickness≈11 nm), and the catalytic promotion of the specific gas‐sensing reaction. The morphological design of the p‐type Co₃O₄ nanostructures and loading of the palladium catalyst have paved a new way to monitoring the most representative indoor air pollutants in a highly selective, sensitive, and reliable manner.     

Controllable Synthesis of Hollow Multishell Structured Co3O4 with Improved Rate Performance and Cyclic Stability for Supercapacitors

Hollow multishelled structures(HoMSs)Co3O4 with specially appointed shell number(double-,triple-and quadruple-)were accurately prepared by a sequential templating approach.Due to the superiorities of inimitable porous multishelled structure,triple-HoMSs Co3O4 achieved the best performance among all the samples with a specific capacitance of 1028.9 F/g at 10 mV/s and 688.2 F/g at 0.5 A/g,respectively.Furthermore,the electrode delivered a high rate performance(89.8%retention at 10 A/g)and excellent cycle stability(6.8%loss over 2000 cycles),showing a great promise for practical application in the future.     

Design of a New Non‐enzymatic Sensor Based on a Substituted A2BO4+δ Perovskite for the Voltammetric Detection of Glucose

Instant determination of glucose levels is necessary to monitor the treatment of diabetes. The next generation of electrochemical sensors aims to eliminate the use of enzymes because of their lack of stability and the complex procedure to immobilize them on the electrode. In this paper Pr_1.92Ba_0.08Ni0.₉₅Zn_0.05O_4+δ perovskite, a A₂BO_4+δ type, was tested, for the first time for non enzymatic detection of glucose. It was synthesized by a sol‐gel method. The obtained crystallized powder was structurally characterized by XRD, morphologically characterized by SEM and EDX and electrochemically characterized. A monoclinic crystallographic system was formed. The presence of Pr₂O₃ during synthesis and calcination is in agreement with the formation of defects in the crystalline network and the disproportionation of Ni^III sites into Ni^II and Ni^IV, due to the substitution of Pr by Ba. The oxido‐reduction of Ni^II sites is observed by cyclic voltammetry. The electrocatalytic oxidation of glucose through the electrooxidized Ni^II site was observed on a gold electrode, at 481 mV. The analytical performance of this glucose sensor is good in comparison to previously published ABO₃ perovskite modified electrodes, in terms of dynamic range (1.5 μM–7000 μM) and detection limit (0.5 μM). Its application to human serum shows that there is no interference for glucose detection.     

Chemoselective Hydrazine‐mediated Transfer Hydrogenation of Nitroarenes by Co3O4 Nanoparticles Immobilized on an Al/Si‐mixed Oxide Support

Cobalt oxide nanoparticles (size 2 to 3.5 nm) were successfully impregnated on an alumina–silica (mixed oxide) support through an experimentally viable and easily reproducible protocol. The prepared material was well characterized by XRD, HR‐TEM, BET surface area, EDX and XPS analyses. Porous alumina–silica having a high surface area served as a protective heterogeneous support on which the well‐dispersed Co₃O₄ nanoparticles served as an active catalytic species for the hydrazine‐mediated transfer hydrogenation of nitroarenes. About 2 mol % of the active catalyst in ethanol at 60 °C was adequate for a successful conversion. Moreover, transfer hydrogenation of nitroarenes by the catalyst was found to take place chemoselectively in the presence of other labile functional groups such as halide, alkene, nitrile, carbonyl, and ester. This inexpensive catalyst was also able to catalyze the reaction on a gram scale reaction and found to be robust and recyclable up to eight runs.     

Glucose and pH Dual‐Responsive Nanogels for Efficient Protein Delivery

Direct delivery of protein suffers from their in vitro and in vivo instability, immunogenicity, and a relatively short half‐life within the body. To overcome these challenges, pH and glucose dual‐responsive biodegradable nanogels comprised of dextran and poly(L‐glutamic acid)‐g‐methoxy poly‐(ethylene glycol)/phenyl boronic acid (PLG‐g‐mPEG/PBA) are designed. The cross‐linked network imparted drug‐loading efficacy of α‐amylase up to 55.6% and hyaluronidase up to 29.1%. In vitro protein release profiles reveal that the release of protein is highly dependent on the pH or glucose concentrations, that is, less amount of protein is released at pH 7.4 or healthy blood glucose level (1 mg mL^?1 glucose), while quicker release of protein occurs at pH 5.5 or diabetic blood glucose level (above 3 mg mL^?1 glucose). Circular dichroism spectra show that the secondary structure of released protein is maintained compared to naive protein. Overall, the nanogels have provided a simple and effective strategy to deliver protein.     

Biomass‐derived Nitrogen and Phosphorus Co‐doped Hierarchical Micro/mesoporous Carbon Materials for High‐performance Non‐enzymatic H2O2 Sensing

Nitrogen and phosphorus co‐doped hierarchical micro/mesoporous carbon (N,P‐MMC) was prepared by simple thermal treatment of freeze‐dried okra in the absence of any other additives. The 0.96 wt % of N and 1.47 wt % of P were simultaneously introduced into the graphitic framework of N,P‐MMC, which also possesses hierarchical porous structure with mesopores centered at 3.6 nm and micropores centered at 0.79 nm. Most importantly, N,P‐MMC carbon exhibits excellent catalytic activity for electrocatalytic reduction of H₂O₂, resulting in a new strategy to construct non‐enzymatic H₂O₂ sensor. The N,P‐MMC‐based H₂O₂ sensor displays two linear detection range about 0.1 mM–10 mM (R²=0.9993) and 20 mM–200 mM (R²=0.9989), respectively. The detection limit is estimated to be 6.8 μM at a signal‐to‐noise ratio of 3. These findings provide insights into synthesizing functional heteroatoms doped porous carbon materials for biosensing applications.     

Synthesis of Tri‐functional Core‐shell CuO@carbon Quantum Dots@carbon Hollow Nanospheres Heterostructure for Non‐enzymatic H2O2 Sensing and Overall Water Splitting Applications

A core‐shell structure with CuO core and carbon quantum dots (CQDs) and carbon hollow nanospheres (CHNS) shell was prepared through facile in‐situ hydrothermal process. The composite was used for non‐enzymatic hydrogen peroxide sensing and electrochemical overall water splitting. The core‐shell structure was established from the transmission electron microscopy image analysis. Raman and UV‐Vis spectroscopy analysis confirmed the interaction between CuO and CQDs. The electrochemical studies showed the limit of detection and sensitivity of the prepared composite as 2.4 nM and 56.72 μA μM^?1 cm^?2, respectively. The core‐shell structure facilitated better charge transportation which in turn exhibited elevated electro‐catalysis towards hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and overall water splitting. The overpotential of 159 mV was required to achieve 10 mA cm^?2 current density for HER and an overpotential of 322 mV was required to achieve 10 mA cm^?2 current density for OER in 1.0 M KOH. A two‐electrode system was constructed for overall water splitting reaction, which showed 10 and 50 mA cm^?2 current density at 1.83 and 1.96 V, respectively. The prepared CuO@CQDs@CHNS catalyst demonstrated excellent robustness in HER and OER catalyzing condition along with overall water splitting reaction. Therefore, the CuO@CQDs@CHNS could be considered as promising electro‐catalyst for H₂O₂ sensing, HER, OER and overall water splitting.     

Anchoring H3PW12O40 on aminopropylsilanized spinel‐type cobalt oxide (Co3O4‐SiPrNH2/H3PW12O40): A novel nanohybrid adsorbent for removing cationic organic dye pollutants from aqueous solutions

In this work, phosphotungstic acid (H₃PW₁₂O₄₀; PW₁₂) was chemically anchored on aminopropylsiloxane functionalized spherical Co₃O₄ nanoparticles (Co₃O₄–SiPrNH₂) and the resultant nanocomposite (Co₃O₄–SiPrNH₂/PW₁₂) was fully characterized. The results demonstrated successful anchoring of PW₁₂ on the surface of Co₃O₄–SiPrNH₂nanoparticles. The Co₃O₄–SiPrNH₂/PW₁₂ nanohybrid indicated a specific surface area of 42.14 m² g^?1, which was greater than that of pure PW₁₂ (ca. 5 m² g^?1). The adsorption efficiency of this novel adsorbent nanomaterial was evaluated for removing methylene blue (MB), rhodamine B (RhB) and methyl orange (MO) dyes from aqueous solutions. The hybrid nanomaterial exhibited a high adsorption rate and selective adsorptivity for the cationic MB and RhB dyes compared to those for anionic MO dye. The prepared hybrid nanomaterial removed over 98% of MB within 12 min. The effects of initial pH, contact time, adsorbent dosage, and temperature were investigated on the adsorption process. The adsorption capacity of nanohybrid for cationic MB dye was 38.46 mg g^‐1. Also, adsorption kinetics indicated that the adsorption by Co₃O₄–SiPrNH₂/PW₁₂ was well‐modeled using pseudo‐second‐order kinetic model. Finally, thermodynamic parameters revealed that the adsorption was endothermic and spontaneous. The adsorption rate and ability of the Co₃O₄–SiPrNH₂/PW₁₂ were enhanced as compared with Co₃O₄ and Co₃O₄–SiPrNH₂ samples due to enhanced electrostatic attraction intraction. The nanohybride was easily separated and reused without any change in structure. Thus, it could be a promising green adsorbent for removing organic pollutants in water.     

草酸锌空心纳米结构的一步固相合成及其表征

本文利用醋酸锌和草酸的一步低热固相化学反应制备了草酸锌空心纳米球，并通过在该反应体系中加入表面活性剂聚乙二醇400得到了草酸锌空心纳米链。采用X-射线粉末衍射（XRD）、透射电镜（TEM）、高倍透射电镜(HRTEM)、扫描电镜(SEM)、红外(IR) 以及热重-差热(TG/DTA)分析对所合成的样品进行了表征.