Nickel Catalysts Supported on Acetylene Black for High-Efficient Electrochemical Oxidation and Sensitive Detection of Glucose.
ABSTRACT: Electrocatalytic glucose oxidation is a very important reaction in glucose fuel cell and medical diagnosis, which is limited by sluggish reaction kinetics and low diffusion coefficient. Herein, a composite (donated as Ni6/AB) consisting of atomically precise nickel catalyst with defined crystal structure [Ni6(SC12H25)12] and acetylene black(AB) has been initiated as a novel and high-efficient non-noble metal catalyst for the electrochemical oxidation of glucose benefiting from its high exposure of active sites and increased electron/mass transport. The present Ni6/AB composites display the onset potential of +1.24?V and the maximum current density of 5?mA?cm-2 at the potential of +1.47?V in the electrolyte of 0.1?M KOH with 5?mM glucose. This electrochemical performance is much superior to the alone nickel catalysts, acetylene black, and previous reported nanomaterials. Furthermore, the obtained Ni6/AB composites are also expected to find important application in the electrochemical detection of glucose due to its high electrochemical performance. The sensitivity and the detection of limit are determined to be 0.7709?mA?cm-2?mM-1 and 1.9 ?M, respectively. Our study demonstrates that atomically precise nickel catalysts on acetylene black could be potential promising materials for next-generation energy devices and electrochemical sensors.
Project description:Electrochemical water splitting requires efficient water oxidation catalysts to accelerate the sluggish kinetics of water oxidation reaction. Here, we report a promisingly dendritic core-shell nickel-iron-copper metal/metal oxide electrode, prepared via dealloying with an electrodeposited nickel-iron-copper alloy as a precursor, as the catalyst for water oxidation. The as-prepared core-shell nickel-iron-copper electrode is characterized with porous oxide shells and metallic cores. This tri-metal-based core-shell nickel-iron-copper electrode exhibits a remarkable activity toward water oxidation in alkaline medium with an overpotential of only 180?mV at a current density of 10?mA?cm-2. The core-shell NiFeCu electrode exhibits pH-dependent oxygen evolution reaction activity on the reversible hydrogen electrode scale, suggesting that non-concerted proton-electron transfers participate in catalyzing the oxygen evolution reaction. To the best of our knowledge, the as-fabricated core-shell nickel-iron-copper is one of the most promising oxygen evolution catalysts.
Project description:In this work, porous NiMn<sub>2</sub>O<sub>4</sub> nanosheet arrays on nickel foam (NiMn<sub>2</sub>O<sub>4</sub> NSs@NF) was successfully fabricated by a simple hydrothermal step followed by a heat treatment. Porous NiMn<sub>2</sub>O<sub>4</sub> NSs@NF is directly used as a sensor electrode for electrochemical detecting glucose. The NiMn<sub>2</sub>O<sub>4</sub> nanosheet arrays are uniformly grown and packed on nickel foam to forming sensor electrode. The porous NiMn<sub>2</sub>O<sub>4</sub> NSs@NF electrode not only provides the abundant accessible active sites and the effective ion-transport pathways, but also offers the efficient electron transport pathways for the electrochemical catalytic reaction by the high conductive nickel foam. This synergy effect endows porous NiMn<sub>2</sub>O<sub>4</sub> NSs@NF with excellent electrochemical behaviors for glucose detection. The electrochemical measurements are used to investigate the performances of glucose detection. Porous NiMn<sub>2</sub>O<sub>4</sub> NSs@NF for detecting glucose exhibits the high sensitivity of 12.2?mA?mM<sup>-1</sup> cm<sup>-2</sup> at the window concentrations of 0.99-67.30 ?M (correlation coefficient?=?0.9982) and 12.3?mA?mM<sup>-1</sup> cm<sup>-2</sup> at the window concentrations of 0.115-0.661?mM (correlation coefficient?=?0.9908). In addition, porous NiMn<sub>2</sub>O<sub>4</sub> NSs@NF also exhibits a fast response of 2?s and a low LOD of 0.24?µM. The combination of porous NiMn<sub>2</sub>O<sub>4</sub> nanosheet arrays and nickel foam is a meaningful strategy to fabricate high performance non-enzymatic glucose sensor. These excellent properties reveal its potential application in the clinical detection of glucose.
Project description:The development of high-performance non-platinum group metal (non-PGM) catalysts for the oxygen reduction reaction (ORR) is still of significance in promoting the commercialization of proton exchange membrane fuel cells (PEMFCs). In this work, a "hierarchically porous carbon (HPC)-supporting" approach was developed to synthesize highly ORR active Fe-phenanthroline (Fe-phen) derived Fe-N x -C catalysts. Compared to commercial carbon black supports, utilizing HPCs as carbon supports can not only prevent the formation of inactive iron nanoparticles during pyrolysis but also optimize the porous morphology of the catalysts, which eventually increases the amount of reactant-accessible and atomically dispersed Fe-N x active sites. The prepared catalyst therefore exhibits a remarkable ORR activity in both half-cells (half-wave potential of 0.80 V in 0.5 M H2SO4) and H2-air PEMFCs (442 mA cm-2 at a working voltage of 0.6 V), making it among the best non-PGM catalysts for PEMFCs.
Project description:The development of catalysts with earth-abundant elements for efficient oxygen evolution reactions is of paramount significance for clean and sustainable energy storage and conversion devices. Our group demonstrated recently that the electrochemical tuning of catalysts via lithium insertion and extraction has emerged as a powerful approach to improve catalytic activity. Here we report a novel in situ electrochemical oxidation tuning approach to develop a series of binary, ternary, and quaternary transition metal (e.g., Co, Ni, Fe) oxides from their corresponding sulfides as highly active catalysts for much enhanced water oxidation. The electrochemically tuned cobalt-nickel-iron oxides grown directly on the three-dimensional carbon fiber electrodes exhibit a low overpotential of 232 mV at current density of 10 mA cm(-2), small Tafel slope of 37.6 mV dec(-1), and exceptional long-term stability of electrolysis for over 100 h in 1 M KOH alkaline medium, superior to most non-noble oxygen evolution catalysts reported so far. The materials evolution associated with the electrochemical oxidation tuning is systematically investigated by various characterizations, manifesting that the improved activities are attributed to the significant grain size reduction and increase of surface area and electroactive sites. This work provides a promising strategy to develop electrocatalysts for large-scale water-splitting systems and many other applications.
Project description:Nickel-encapsulated nitrogen-doped carbon nanotubes (Ni-TiO2-NCNTs) are synthesized via chemical vapor deposition by thermal decomposition of acetylene with acetonitrile vapor at 700 °C on the Ni-TiO2 matrix. TiO2 is used as a dispersant medium for Ni nanoparticles, which assists in higher CNT growth at high temperatures. A reference catalyst is made by following the similar procedure without acetonitrile vapor, which is called a Ni-TiO2-CNT. Acid treatment of these two catalysts dissolved Ni on the surface of CNTs-NCNTs, producing catalysts with enhanced surface area and defects. The transmission electron microscopy-energy-dispersive X-ray spectra analysis of acid-treated version of the catalysts confirmed the presence of encapsulated Ni. Oxygen reduction reaction (ORR) activity of these catalysts was analyzed in 0.1 N KOH solution. Among these, the acid-treated Ni-TiO2-NCNT exhibited highest ORR onset potential of 0.88 V versus reversible hydrogen electrode and a current density of 3.7 mA cm-2 at 170 ?g cm-2 of catalyst loading. The stability of the acid-treated Ni-TiO2-NCNT is proved by cyclic voltammetry and chronoamperometry measurements which are done for 800 cycles and 100 h, respectively. Primarily N doping of CNTs is the reason behind the improved ORR activity.
Project description:Electrochemical water splitting is known as a potential approach for sustainable energy conversion; it produces H2 fuel by utilizing transition metal-based catalysts. We report a facile synthesis of FeCo2O4@carbon dots (CDs) nanoflowers supported on nickel foam through a hydrothermal technique in the absence of organic solvents and an inert environment. The synthesized material with a judicious choice of CDs shows superior performance in hydrogen and oxygen evolution reactions (HER and OER) compared to the FeCo2O4 electrode alone in alkaline media. For HER, the overpotential of 205 mV was able to produce current densities of up to 10 mA cm-2, whereas an overpotential of 393 mV was needed to obtain a current density of up to 50 mA cm-2 for OER. The synergistic effect between CDs and FeCo2O4 accounts for the excellent electrocatalytic activity, since CDs offer exposed active sites and subsequently promote the electrochemical reaction by enhancing the electron transfer processes. Hence, this procedure offers an effective approach for constructing metal oxide-integrated CDs as a catalytic support system to improve the performance of electrochemical water splitting.
Project description:In this work a novel bimetallic nickel oxide/copper oxide metal-organic framework (NiO/CuO MOF) has been developed by using two linkers: Benzene Dicarboxylic acid (BDC) and Pyrazine. The composites of NiO/CuO MOF with different amounts of reduced graphene oxide (rGO) were synthesized through a hydrothermal method and subsequently characterized by multiple significant techniques like XRD, SEM, EDX, FTIR and Raman IR for an investigation of their structural and morphological properties. The prepared series of material was later employed for electrochemical oxidation of methanol, tested by cyclic voltammetry (CV) in basic medium on a modified glassy carbon electrode (GCE). The electrochemical response depicts that increasing concentration of rGO enhances the electrocatalytic activity of the catalyst for methanol oxidation reaction (MOR). The catalyzed oxidation reaction of methanol by NiO/CuO MOF and rGO-NiO/CuO MOF composites give a superlative current density of 437. 28 mA/cm2 at 0.9 V potential at 50 mV/s scan rate. This activity makes it a promising catalytic material for electrolysis of methanol in direct methanol fuel cell (DMFC).
Project description:The design of cheap, non-toxic, and earth-abundant transition metal catalysts for selective hydrogenation of alkynes remains a challenge in both industry and academia. Here, we report a new atomically dispersed copper (Cu) catalyst supported on a defective nanodiamond-graphene (ND@G), which exhibits excellent catalytic performance for the selective conversion of acetylene to ethylene, i.e., with high conversion (95%), high selectivity (98%), and good stability (for more than 60 h). The unique structural feature of the Cu atoms anchored over graphene through Cu-C bonds ensures the effective activation of acetylene and easy desorption of ethylene, which is the key for the outstanding activity and selectivity of the catalyst.
Project description:Pt nanoparticles-laden graphene (Pt/GR) composites were synthesized in the gas phase from a mixture of ethanol and Pt precursor by microwave plasma spray pyrolysis. The morphology of Pt/GR composites has the shape of wrinkled sheets of paper, while Pt nanoparticles (Pt NPs) that are less than 2.6?nm in the mean diameter are uniformly well deposited on the surface of GR sheets stacked in only three layers. The Pt/GR composite prepared with 20 wt% of Pt had the highest specific surface area and electrochemical surface area of up to 402?m(2) g(-1) and 77?m(2) g(-1) (Pt), respectively. In addition, the composite showed superior electrocatalytic activity compared with commercial Pt-carbon black. The excellent electrocatalytic activity was attributed to the high specific surface area and electrochemical surface area of the Pt/GR composite directly produced by microwave plasma spray pyrolysis. Thus, it is clearly expected that the Pt/GR composite is a promising material for DMFC catalysts.
Project description:Industrial applications of Pt-based oxygen-reduction-reaction (ORR) catalysts are limited by high cost and low stability. Here, facile large-scale synthesis of sub-3-nm ordered Pt3In clusters on commercial carbon black as ORR catalyst that alleviates both these shortcomings is reported. As-prepared Pt3In/C exhibits a mass activity of 0.71 mA mg-1 and a specific area activity of 0.91 mA cm-2 at 0.9 V vs reversible hydrogen electrode, which are 4.1 and 2.7 times the corresponding values of commercial Pt/C catalysts. The as-prepared ordered Pt3In/C catalyst is also remarkably stable with negligible activity and structural decay after 20 000 accelerated electrochemical durability cycles, due to its ordered structure. Density-functional-theory calculations demonstrate that ordered-Pt3In is more energetically favorable for ORR than the commercial Pt/C catalysts because ?G O is closer to the peak of the volcano plot after ordered incorporation of indium atoms.