A highly sensitive non-enzymatic glucose sensor based on Cu nanoparticles (CuNPs)/polyaniline (PANI)/graphene nanocomposite was fabricated via simple in-situ reduction of Cu precursor in polyaniline ...nanofibers under mild conditions followed by mechanical mixing with graphene suspension to form the composites with different graphene contents (0.5%, 1%, and 2%). The properties of nanocomposites were characterized by SEM, TEM, XRD, UV–Vis, and XPS. The CuNPs (d=2–4nm) only slightly altered the ordered structure of PANI. It was found that CuNPs have direct electronic interaction with PANI via the N atoms on the polymer backbone, which enabled fast electrons transfer from electrode to CuNPs through graphene and PANI. The CuNPs/PANI/graphene nanocomposites were coated on a glassy carbon electrode for the investigation of their electrochemical properties. Both CuNPs/PANI and CuNPs/PANI/graphene showed high sensitivity towards glucose oxidation which occurred at ~0.5V vs. SCE. The best performance was achieved by the CuNPs/PANI/1% graphene-modified electrode which showed sensitivity of ~150mAcm−2M−1, detection limit of 0.27μM (S/N=3), and response time of about 3s. This system was also highly selective towards glucose oxidation that almost no signal was detected from interferents such as ascorbic acid and dopamine, demonstrating its great potential as a non-enzymatic glucose sensor.
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Although explosive studies on pursuing high-performance direct fuel cells in the past decades have been carried out, the lack of cost-efficient anode catalysts for oxidation reaction of clean fuel ...remain a harsh challenge that greatly hinder the development of fuel cell technology. For addressing these issues, we herein combined both of the morphological and component advantages to engineer an advanced monodispersed PdCu nanoalloy catalysts with ultrasmall diameter. A series of electrochemical measurements have revealed that the resulted monodispersed Pd1Cu1 nanospheres can meet the requirement of high surface area with a high electrochemically active surface area (EASA) values of 31.1 m2 g−1, which is 4.06 times higher than that of commercial Pd/C. Similarly, the newly-prepared monodispersed PdCu nanospheres also exhibited much higher mass activity and durability than single-phase Pd and commercial Pd/C towards ethylene glycol electrooxidation in the alkaline media. This work may open a new way for maximizing the electrocatalytic performances by combining the advantages of well-dispersed property and extremely small size.
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•The sub-5 nm monodispersed PdCu nanospheres have been prepared.•A modified galvanic replacement method has been developed.•The growth and formation mechanism have been explored.•The as-prepared PdCu nanospheres show excellent activity toward EG oxidation.
Fuel cells are a very good candidate to provide energy conversion with green technology. Glucose is used as a fuel in fuel cells since it is easily available and has a high energy density. Herein, ...hydroxyapatite (HAp) was synthesized by precipitation method, and the sodium borohydride (NaBH4) reduction method was used to fabricate HAp supported PdIn (PdIn/HAp) alloy anode catalysts at varying atomic molar ratios for glucose electrooxidation. Structural, crystallographic, and morphological properties of the PdIn/HAps were determined with X-ray diffraction analysis (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), Brunauer-Emmett-Teller (BET) analysis, transmission electron microscopy (TEM), and inductively coupled plasma mass spectrometry (ICP-MS). Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and chronoamperometry (CA) were employed for the electrocatalytic activity and stability of PdIn/Haps toward glucose electrooxidation. The results show that HAp has a boosting effect for PdIn alloy towards glucose electrooxidation. Pd80In20/HAp showed 2.6 times higher electrocatalytic activity than Pd/HAp, and it is the most active and stable catalyst in this study with a specific activity of 5.64 mA/cm2.
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•PdIn/HAp catalysts with varying atomic molar ratios were synthesized by the NaBH4 reduction method.•Pd80In20/HAp exhibited excellent electrocatalytic activity for glucose electrooxidation.•Pd80In20/HAp showed long-term stability as a DGFC anode catalyst.
The contamination of water bodies by antibiotics is a cause of concern due to chronic toxic effects and the possible development of resistance to them by microorganisms, which can lead to serious ...health problems to humans. Thus, in this work, for the first time the degradation of norfloxacin (100mgL−1 NOR in 0.1molL−1 Na2SO4) is carried out electrochemically, using a filter-press flow reactor with boron-doped diamond (BDD) anodes of distinct characteristics. The investigated variables (and their ranges) were solution pH (3, 7, 10, and without specific control), current density (10, 20, and 30mAcm−2), temperature (10, 25, and 40°C), and boron content–sp2/sp3 carbon ratio of the BDD anode (100ppm – 215, 500ppm – 325, and 2500ppm – 284). The NOR electrodegradation performance of the distinct anodes was assessed by monitoring the degradation by-products (aromatic compounds and carboxylic acids), NOR concentration and total organic carbon concentration of the electrolyzed solutions, as well as their toxicity to Escherichia coli (i.e. growth inhibition). For the complete removal of NOR, the best condition (not pH dependent) was attained at 10mAcm−2 and 40°C, when the system is under mass transfer limitations. Concerning NOR oxidation and mineralization rates, mineralization current efficiency, energy consumption, and degradation products, similar results (including the complete detoxification of the electrolyzed solution) were attained for all tested BDD anodes under mass or charge transfer controlled processes. Clearly, the oxidation power of the tested BDD anodes is not affected by the values of their boron content–sp2/sp3 carbon ratio.
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•Small Pt nanoparticles supported on carbon with 40% {100} sites were obtained.•Pd decoration on Pt nanoparticles produced enhanced HCOOH oxidation activity.•The Pd-Pt/C 45 wt% sample ...displayed higher activity (>3 times) than without Pd.•HCOOH oxidation shifted about ~200 mV to lower overpotentials after Pd decoration.
The use of shape-controlled nanomaterials represents an elegant way to improve the performance of many electrochemical reactions. However, two main aspects must be still optimised: decreasing particle size and increasing their activity. This study shows that the deposition of Pd on different small (3–5 nm) supported Pt materials (displaying a preferential structure containing ~40% of Pt{100} terraces) leads to a great enhancement in the electrocatalytic activity towards the formic acid electrooxidation reaction. After Pd decoration, the oxidation takes place at lower overpotentials and oxidation current densities are significantly higher than those observed with all the bare Pt/C samples. For the Pt/C 45% catalyst, the intrinsic activity after Pd deposition was more than three times of that without Pd, while the oxidation overpotential shifted about ~200 mV to lower overpotentials.
The direct alcohol fuel cell has recently emerged as an important energy conversion device. In the present article, superior alcohol (ethanol, ethylene glycol, and glycerol) electrooxidation ...performance using trimetallic platinum–palladium–nickel (PtPdNi) alloy nanoparticles of diameters from 2–4 nm supported on a reduced graphene oxide (rGO) electrocatalyst is demonstrated. A simple and single-step solvothermal technique is adopted to fabricate the alloy/rGO hybrid electrocatalysts by simultaneous reduction of metal ions and graphene oxide. The detailed electrochemical investigation revealed that the performance of the trimetallic/rGO hybrid toward electrooxidation of different alcohols is higher than that of bimetallic alloy/rGO hybrids and the state-of-the-art Pt/C catalyst. The incorporation of Ni into the PtPd alloy is found to change the surface of the electronic structure PtPd alloy leading to higher electrochemical surface areas and improved kinetics. In addition, the hydrophilic nature of Ni not only facilitates alcohol electrooxidation but also electrooxidation of residual carbon impurities formed on the catalyst surface, thus reducing catalyst poisoning, demonstrating its role in the development of anode catalysts for the alcohol fuel cells.
•The novel N-doped Ti3C2 Pd based catalysts are designed and synthesized.•Pd/N-Ti3C2-28 h possesses the conspicuous lamellar morphology and uniform metal Pd particles distribution.•Pd/N-Ti3C2-28 h ...catalyst exhibit the higher ethanol oxidated current densities, electrochemical stability and cycle stability than the commercial PdC.•Our work can provide a new way to consider the other MXene materials as the new catalyst support for direct alcohol fuel cells.
In this article, the novel N-doped Ti3C2 support Pd-based catalyst (Pd/N-Ti3C2-28 h) is successfully prepared by suitable HF-etching and NH3.H2O doping, which possess the conspicuous lamellar morphology and uniform metal Pd distribution. The Pd/N-Ti3C2-28 h with N-doping has the higher content of Pd (~5.33 at%) than that of without N-doping (~1.38 at%) under the same mass of Pd loading. Being explored as the catalyst for ethanol electrooxidation in alkaline medium, the Pd/N-Ti3C2-28 h catalyst exhibits the higher electrochemically active surface areas, ethanol oxidated current densities (~36.71 mA.cm−2) and electrochemical stability than those of the Pd/Ti3C2-28 h, the other Pd/N-Ti3C2 catalysts with different HF-etching time (20,24 and 32 h), and the commercial Pd/C (j = ~12.73 mA.cm−2). Such excellent electrocatalytic performance can be ascribed to synergy of obvious layer-structure of the Ti3C2 support and the NH3.H2O doping, which lead to the higher binding energy and more electron transfer of the metal Pd and Ti3C2, thereby improving the Pd loading on the Ti3C2. And the current densities after 200 redox cycles of Pd/Ti3C2-28 h can retain 78.3% of the maximum capacity, demonstrating the high cycle stability. Thus, the Pd/N-Ti3C2-28 h can become the potential candidates as the anode catalyst for the ethanol electrooxidation in alkaline medium.
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Catalytic performance and NaBH4 utilization are two crucial concerns in the electrooxidation of NaBH4. To improve the inherent properties of regular performance and low fuel utilization of the ...transition metal Co and Ni, an efficient anode catalyst of ultra-thin CoNi nanosheets modified novel 3D self-supported reduced graphene oxide foam is prepared in this work. The alkaline condition borohydride oxidation reaction on the prepared catalyst is investigated in a typical three-electrode system. The prepared catalyst shows a high performance due to the large electrochemical active surface area, low activation energy (8.29 kJ·mol−1), and the small electrochemical impedance it embraced. Linear scan voltammetry recorded in a low concentration of NaBH4 suggests that borohydride oxidation is a first-order reaction on the prepared catalyst. Based on the unique structure of the catalyst, which is useful to capture the hydrogen and perform further oxidation of hydrogen, higher utilization of NaBH4 achieved on the catalyst. Besides, the prepared anode catalyst applied to a direct borohydride-hydrogen peroxide fuel cell (DBHPFC). The results of polarization curve and power density curves, as well as stability research, all indicate that the as-prepared catalyst is a highly efficient anode material for application in DBHPFC.
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•Novel 3D self-supported rGO foam skeleton was prepared by a simple template method.•The catalytic activity of CoNi-NS/rGO foam is higher than CoNi-NS/Ni foam electrode.•Self-supported rGO foam matrix improved the utilization efficiency of NaBH4.•CoNi-NS/rGO foam anode catalyst exhibited highest power density of 140 mW·cm−2.
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•An efficient synthesis strategy of nickel cobalt sulfide which is assisted by H2O2 was proposed.•A catalyst H-0.3Co-Ni3S2 was synthesized and showed excellent performance in the ...electrooxidation of HMF.•A novel strategy of stepwise electrolysis was come up and can accelerate HMF electrooxidation while inhibiting OER.
Electrooxidation of 5‑Hydroxymethylfurfural (HMF) is considered a promising strategy for replacing the sluggish oxygen evolution reaction (OER) of electrolytic water, which can reduce the consumption of hydrogen production and the risk of gas mixing and obtain value-added products. Herein, a nanosheet with nanoflower catalyst (H-0.3Co-Ni3S2) was synthesized via a one-step hydrothermal process with the assistance of hydrogen peroxide (H2O2) for the electrooxidation of HMF. Adding H2O2 and Co can decrease Ni's outer layer electronic cloud density, which benefits the catalyst's oxidation and catalyzes the HMF electrooxidation. H-0.3Co-Ni3S2 shows the superior performance of the HMF electrochemical oxidation with the initial potential of 1.25 V vs. RHE and the voltage of 1.38 V vs. RHE at 200 mA cm−2 under the electrolyte of 1 M KOH with 10 mM HMF. The conversion rate, yield and Faraday efficiency of HMF electrooxidation for H-0.3Co-Ni3S2 in the electrolyte of 1 M KOH with 10 mM HMF are 98.2 %, 97.6 % and 97.6 %, respectively. Besides, we provide a novel stepwise electrolysis strategy that can inhibit OER effectively while electrolyzing large-concentration HMF rapidly. Finally, in an electrolyte of 1 M KOH with 30 mM HMF, the conversion rate, yield and Faraday efficiency achieve 100 %, 91.9 % and 97.4 %, respectively.
A simple process for preparing mesoporous chromium nitride (CrN) by the ammonolysis of a bulk ternary oxide (K2Cr2O7) is reported. The products were characterized by Rietveld refinement of powder ...X-ray diffraction patterns, scanning electron microscopy (SEM), and nitrogen adsorption/desorption analysis. Pore sizes ranging from 10 to 20 nm are easily accessible. The conductivity of mesoporous CrN powder compressed at 35 bar is 54 S/cm. A Pt/CrN catalyst prepared from the mesoporous CrN shows a negative onset potential for methanol electrooxidation (0.20 V vs SCE) similar to that of Pt/C (0.22 V vs SCE). The electrochemically active specific surface area (ECSA) of the Pt/CrN catalyst (82 m2/g) was only slightly higher than that of Pt/C (75 m2/g). More importantly, the Pt/CrN catalyst demonstrates high tolerance to corrosion and is a candidate to replace carbon black, which is known to corrode under high potentials, as a support for fuel cell catalysts. This work provides an efficient method for preparing mesoporous metal nitrides that are promising supports for the oxidation of small organic molecules in fuel cells.
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