Activity For Electrochemical Oxidation Research Articles

Ultra-Low-Potential Methanol Oxidation on Single-Ir-Atom Catalyst.

Methanol oxidation plays a central role to implement sustainable energy economy, which is restricted by the sluggish reaction kinetics due to the multi-electron transfer process accompanied by numerous sequential intermediate. In this study, an efficient cascade methanol oxidation reaction is catalyzed by single-Ir-atom catalyst at ultra-low potential (<0.1 V) with the promotion of the thermal and electrochemical integration in a high temperature polymer electrolyte membrane electrolyzer. At the elevated temperature, the electron deficient Ir site with higher methanol affinity could spontaneous catalyze the CH3OH dehydrogenation to CO under the voltage, then the generated CO and H2 was electrochemically oxidized to CO2 and proton. However, the methanol cannot thermally decompose with the voltage absence, which confirm the indispensable of the coupling of thermal and electrochemical integration for the methanol oxidation. By assembling the methanol oxidation reaction with hydrogen evolution reaction with single-Ir-atom catalysts in the anode chamber, a max hydrogen production rate reaches 18 mol gIr -1 h-1, which is much greater than that of Ir nanoparticles and commercial Pt/C. This study also demonstrated the electrochemical methanol oxidation activity of the single atom catalysts, which broadens the renewable energy devices and the catalyst design by an integration concept.

Ultra‐Low‐Potential Methanol Oxidation on Single‐Ir‐Atom Catalyst

AbstractMethanol oxidation plays a central role to implement sustainable energy economy, which is restricted by the sluggish reaction kinetics due to the multi‐electron transfer process accompanied by numerous sequential intermediate. In this study, an efficient cascade methanol oxidation reaction is catalyzed by single‐Ir‐atom catalyst at ultra‐low potential (&lt;0.1 V) with the promotion of the thermal and electrochemical integration in a high temperature polymer electrolyte membrane electrolyzer. At the elevated temperature, the electron deficient Ir site with higher methanol affinity could spontaneous catalyze the CH3OH dehydrogenation to CO under the voltage, then the generated CO and H2 was electrochemically oxidized to CO2 and proton. However, the methanol cannot thermally decompose with the voltage absence, which confirm the indispensable of the coupling of thermal and electrochemical integration for the methanol oxidation. By assembling the methanol oxidation reaction with hydrogen evolution reaction with single‐Ir‐atom catalysts in the anode chamber, a max hydrogen production rate reaches 18 mol gIr−1 h−1, which is much greater than that of Ir nanoparticles and commercial Pt/C. This study also demonstrated the electrochemical methanol oxidation activity of the single atom catalysts, which broadens the renewable energy devices and the catalyst design by an integration concept.

A PEDOT: PSS/GO fiber microelectrode fabricated by microfluidic spinning for dopamine detection in human serum and PC12 cells.

Rapid and accurate in situ determinationof dopamine is of great significance in the study of neurological diseases. In this work, poly (3,4-ethylenedioxythiophene): poly (styrenesulfonic acid) (PEDOT: PSS)/graphene oxide (GO) fibers were fabricated by an effective method based on microfluidic wet spinning technology. The composite microfibers with stratified and dense arrangement were continuously prepared by injecting PEDOT: PSS and GO dispersion solutions into a microfluidic chip. PEDOT: PSS/GO fiber microelectrodes with high electrochemical activity and enhanced electrochemical oxidation activity of dopamine were constructed by controlling the structure composition of the microfibers with varying flow rate. The fabricated fiber microelectrode had a low detection limit (4.56 nM) and wide detection range (0.01-8.0 µM) for dopamine detection with excellent stability, repeatability, and reproducibility. In addition, the PEDOT: PSS/GO fiber microelectrode prepared was successfully used for the detection of dopamine in human serum and PC12 cells. The strategy for the fabrication of multi-component fiber microelectrodes isa new and effective approach for monitoring the intercellular neurotransmitter dopamine and has highpotential as an implantable neural microelectrode.

Tailoring Electrochemical Water Oxidation Activity from the Isostructural Series of Alkaline‐Stable Bimetallic Fe,Ni‐Azolate Metal–Organic Frameworks

AbstractIncorporating electrocatalytic active sites into the reticular framework allows for the design of novel catalytic structures promoting desired catalytic reactions with efficient mass transfer. However, to fully exploit the advantages of such a framework, it is crucial to ensure the electrochemical stability of the material. In this context, alkaline‐stable bimetallic MxNi2‐xCl2BTDD (M = Fe, Co) metal–organic frameworks (MOFs) are employed as electrocatalysts for alkaline water oxidation reaction (WOR) to understand the correlation between secondary metal incorporation and catalytic activity changes. For a specific Fe ratio within the MOF, the optimal catalytic activity is achieved at an overpotential of 315 mV at a WOR current density of 10 mA cm−2geo. Based on its well‐defined crystal structure and uniformly arranged metal nodes, which are not limited to specific facets, the cooperative electrocatalytic mechanism during the faradaic WOR process is investigated through operando Raman spectroscopy and density functional theory calculations. These results enable the interpretation of the electrochemical WOR mechanism based on MOF, providing a further fundamental understanding of electrocatalytic activity in bimetallic systems.

Medium-entropy perovskite Pr0.4Ba0.2Ca0.2La0.2Co0.2Fe0.8O3 as a promising bifunctional electrocatalyst for electrochemical energy conversion device

Reversible solid oxide cells (R-SOCs) are considered to be a promising energy conversion device that can achieve efficient conversion between fuel and electrical energy. However, there are still significant challenges in developing a promising bifunctional electrocatalyst as an electrode material for R-SOC devices. Here, a medium-entropy perovskite Pr0.4Ba0.2Ca0.2La0.2Co0.2Fe0.8O3 (PBCLCF) is designed to enhance the electrochemical oxidation and reduction activity. Under hydrogen atmosphere, cobalt metals are in situ exsolved from the perovskite structure, accompanied by partial phase transformation (denoted as R-PBCLCF). Characterizations show that PBCLCF and R-PBCLCF can increase the concentration of oxygen vacancies, thereby enhancing oxygen migration ability. Combined with electrochemical impedance spectroscopy (EIS) and distribution of relaxation times (DRT) analysis, the medium-entropy PBCLCF exhibits better oxygen reduction reaction (ORR) activity and R-PBCLCF shows better hydrogen oxidation reaction (HOR) activity. Furthermore, the oxygen dissociation is identified as the rate-determining step (RDS) in the ORR process, whereas the HOR process is dominated by the hydrogen adsorption and dissociation. The single cell with (R-)PBCLCF showcases remarkable reversible performance. When O2 is employed as the oxidant and H2 as the fuel, this cell achieves a maximum power density of 468.1 mW cm−2 in solid oxide fuel cell (SOFC) mode at 700 °C. Moreover, when O2 is employed as the oxidant and humidified H2 (30 %H2O) as the fuel, the current density of the cell in solid oxide electrolysis cell (SOEC) mode is −647.3 mA cm−2 at 1.3 V and 700 °C.

Fine‐tuning electronic structure of N‐doped graphitic carbon‐supported Co‐ and Fe‐incorporated Mo2C to achieve ultrahigh electrochemical water oxidation activity

AbstractMo2C is an excellent electrocatalyst for hydrogen evolution reaction (HER). However, Mo2C is a poor electrocatalyst for oxygen evolution reaction (OER). Herein, two different elements, namely Co and Fe, are incorporated in Mo2C that, therefore, has a finely tuned electronic structure, which is not achievable by incorporation of any one of the metals. Consequently, the resulting electrocatalyst Co0.8Fe0.2–Mo2C‐80 displayed excellent OER catalytic performance, which is evidenced by a low overpotential of 214.0 (and 246.5) mV to attain a current density of 10 (and 50) mA cm−2, an ultralow Tafel slope of 38.4 mV dec−1, and long‐term stability in alkaline medium. Theoretical data demonstrates that Co0.8Fe0.2–Mo2C‐80 requires the lowest overpotential (1.00 V) for OER and Co centers to be the active sites. The ultrahigh catalytic performance of the electrocatalyst is attributed to the excellent intrinsic catalytic activity due to high Brunauer–Emmett–Teller specific surface area, large electrochemically active surface area, small Tafel slope, and low charge‐transfer resistance.

Glycerol Electrooxidation over Precision-Synthesized Gold Nanocrystals with Different Surface Facets.

Electrochemical glycerol oxidation (EGO) emerges as a promising route to valorize glycerol, an underutilized byproduct from biodiesel production, into value-added chemicals. This study employed three types of gold (Au) nanocrystals with controlled shapes to elucidate the facet-dependent electrocatalytic behavior in EGO. Octahedral, rhombic dodecahedral, and cubic Au nanocrystals with {111}, {110}, and {100} facets, respectively, were precisely synthesized with uniform size and shape. Rhombic dodecahedra exhibited the lowest onset potential for EGO due to facile AuOH formation, while octahedra showed enhanced electrochemical activity for glycerol oxidation and resistance to poisoning. In-situ FTIR analysis revealed that Au {111} surfaces selectively favored C2 products, whereas Au {100} surfaces promoted C3 product formation, highlighting the significant effect of facet orientation on EGO performance and informing catalyst design.

Catalytic Activity of Atomic Metals Clusters Decorated Polyaniline Electrodes in Electrochemical Oxidation of 1-Propanol

Electrochemical sensors are capable to fast-detect chemicals with a high sensitivity at a low cost. Thanks to these advantages, electrochemical sensors are promising for detections of biomolecules, such as glucose, dopamine, uric acid, etc. The catalytic electrode in a electrochemical sensor is composed of noble noble metals, such as Au and Pd,and a suppoorting material. Polyaniline (PANI)[ 1]is an ideal supporting material for noble metal clusters because of its good electrical conductivity, high stability, large active surface area, and simple preparation process. Recently, PANI decorated with atomic level noble metal clusters is report to show distinct catalytic activity for the electrochemical oxidation of alcohols.[1] However, the effects of the number of the metal atoms in such clusters and the sequence of the atomic level deposition step on their electrocatalytic activity for electrochemical alcohol oxidation remain unexplored.In this presentation, the effects of the number of the metal atoms and the sequence of the atomic level deposition step in the atomic level noble metal clusters on the catalytic activity in electrochemical oxidation of 1-propanol (1-PrOH) are reported. The PANI was deposited on a Pt disk electrode (ϕ = 3 mm) by electrochemical polymerization in a 2 M HBF4 aqueous solution containing 0.1 M of aniline. Then, the PANI deposited electrode was decorated with mono-atomic noble metal clusters, bi-atomic, tri-atomic, or tetra-atomic noble metal clusters. The atomic noble metal clusters are denoted as PdxAuy, where x represents the number of Pd atoms in a cluster and y is the number of the Au atoms. The sources of the Pd and Au were K2PdCl4 and KAuCl4, respectively.. Fig. 1 shows the schematic procedures for fabricating a bi-atomic pure Pd (Pd2) decorated PANI electrode and a PdAu decorated PANI electrode. The catalytic activity for the electrochemical oxidation of 1-PrOH was evaluated by performing cyclic voltammetry measurements with an aqueous solution containing 0.5 M 1-PrOH and 1 M KOH.The catalytic activtiy was found be higher for the Pd2 and Pd4 decorated PANI electrodes than those of the Pd1 and Pd3 decorated PANI electrodes, which revealed odd-even pattern effects as reported in a previous study.[ 1] Furthermore, the catalytic activity was found to be affected by the sequence in deposition of the atomic level noble metal clusters. Reference [1] A. P. Jonke, J. L. Steeb, M. Josowicz, J. Janata, Catal Lett 2013, 143, 531–538. Figure 1

Hydrothermal electrochemical flow reactor to independently control temperature, pressure, and potential for manganese oxide electrodeposition

Electrodeposition has been widely applied for the fabrication of functional materials; however, most previous deposition processes were limited to temperatures of less than 100 °C. Furthermore, reaction pressure was concomitantly determined with the reaction temperature, hindering the full exploration of synthetic conditions. Here, we developed a hydrothermal electrochemical flow reactor equipped with flowing system and that enables the independent control of temperature and pressure and applied this reactor to the synthesis of manganese oxides (MnOx) for electrochemical oxygen evolution reaction. Systematic investigation of temperature and pressure revealed that the crystallinity and morphology of MnOx was influenced by deposition temperature, with particle size decreasing under higher pressure (4 MPa). Electrodeposition at higher temperature (160 °C) at 1 MPa generated a mixed phase of ε- and γ- MnO2, which showed superior electrochemical water oxidation activity to samples prepared at lower temperature (80 and 100 °C, respectively), achieving a current density of 10 mA cm−2 for at least 100 h under acidic conditions (pH 2.3). Our results show that the hydrothermal electrochemical flow reactor allows expanding synthetic parameters for the synthesis of highly functional catalytic materials.

Y-mediated optimization of 3DG-PbO2 anode for electrochemical degradation of PFOS

In our previous study, the three-dimensional graphene-modified PbO2 (3DG-PbO2) anode was prepared for the effective degradation of perfluorooctanesulfonat (PFOS) by the electrochemical oxidation process. However, the mineralization efficiency of PFOS at the 3DG-PbO2 anode still needs to be further improved due to the recalcitrance of PFOS. Thus, in this study, the yttrium (Y) was doped into the 3DG-PbO2 film to further improve the electrochemical activity of the PbO2 anode. To optimize the doping amount of Y, three Y and 3DG codoped PbO2 anodes were fabricated with different Y3+ concentrations of 5, 15, and 30 mM in the electroplating solution, which were named Y/3DG-PbO2-5, Y/3DG-PbO2-15 and Y/3DG-PbO2-30, respectively. The results of morphological, structural, and electrochemical characterization revealed that doping Y into the 3DG-PbO2 anode further refined the β-PbO2 crystals, increased the oxygen evolution overpotential and active sites, and reduced the electron transfer resistance, resulting in a superior electrocatalytic activity. Among all the prepared anodes, the Y/3DG-PbO2-15 anode exhibited the best activity for electrochemical oxidation of PFOS. After 120 min of electrolysis, the TOC removal efficiency was 80.89% with Y/3DG-PbO2-15 anode, greatly higher than 69.13% with 3DG-PbO2 anode. In addition, the effect of operating parameters on PFOS removal was analyzed by response surface, and the obtained optimum values of current density, initial PFOS concentration, pH, and Na2SO4 concentration were 50 mA/cm2, 12.21 mg/L, 5.39, and 0.01 M, respectively. Under the optimal conditions, the PFOS removal efficiency reached up to 97.16% after 40 min of electrolysis. The results of the present study confirmed that the Y/3DG-PbO2 was a promising anode for electrocatalytic oxidation of persistent organic pollutants.

Unveiling the electrochemical CO oxidation activity on support-free porous PdM (M = Fe, Co, Ni) foam-like nanocrystals over a wide pH range

Binary PdM-based nanocrystals are efficient electrocatalysts for a wide range of renewable and green fuel cell applications; however, their poisoning by CO is a great barrier for commercialization, so it is pivotal to solve this issue. Herein, we fabricated support-free PdM alloys (M = Fe, Co, and Ni) by a prompt one-step aqueous-solution co-reduction with sodium borohydride driven by the coalescence growth mechanism. This forms support-free PdM porous foam-like nanostructures with well-defined compositions from the ICP-OES analysis and clean surface without any hazardous chemicals or multiple reaction steps. The as-prepared PdM foam-like nanostructures were demonstrated for carbon monoxide oxidation (COOxid) electrocatalysis at varied electrolyte pH compared with commercial Pd/C catalyst. The foam-like PdFe nanocrystals achieved an excellent electrochemical COOxid activity that was at least 2.18-times of PdCo, 4.35-times of PdNi, and 1.56-times of Pd/C in both alkaline (KOH) and acidic (HClO4) electrolytes, but PdCo was the best in neutral (NaHCO3) medium. The superior activity of PdM is due to the strain and alloying effect, which promoted the superb CO oxidation durability for 1000 cycles than Pd/C catalyst. This study demonstrated the superiority of support-free bimetallic PdM alloys than Pd/C catalyst in all electrolytes, which may open new gates for understanding CO-poisoning in alcohol-based fuel cells.

Polyhedral Coordination Determined Co‐O Activity for Electrochemical Oxidation of Biomass Alcohols

AbstractEarth‐abundant transition metal oxides are promising electrocatalysts for oxidation of biomass alcohols. Here, CoO and Co3O4 are selected as representative cobalt oxide catalysts and grown on carbon fiber paper (CFP) electrodes to reveal the interplay between electronic structure and catalytic activity of catalysts for oxidation of glycerol, diols, and monohydric alcohols. In situ electrochemical tests elucidate that the CoO/CFP electrode has lower interfacial impedance, higher charge transfer, faster oxidation rate, and thereby the higher catalytic activity for alcohol oxidation than the Co3O4/CFP electrode. Especially for glycerol oxidation, the CoO/CFP electrode only requires 1.32 V to reach 10 mA cm−2, the potential is 120 mV lower than that for the Co3O4/CFP electrode. The CoO/CFP electrode can also produce value‐added products such as formate, acetate, and glycolate with high selectivity and efficiency at low energy consumptions from oxidation of biomass alcohols. Theoretical calculations further confirm the dominant role of octahedrally coordinated Co‐O sites in adsorption, activation, and oxidation of C3‐C1 alcohols. This work sheds light on the design of highly efficient transition metal oxide catalysts for oxidation of alcohols by populating octahedral sites in the crystal structure.

Achieve a high electrochemical oxidation activity by a self-assembled cermet composite anode with low Ni content for solid oxide fuel cells

Achieve a high electrochemical oxidation activity by a self-assembled cermet composite anode with low Ni content for solid oxide fuel cells

Bio-Inspired Electrochemical Detection of Nitric Oxide Promoted by Coordinating the Histamine-Iron Phthalocyanine Catalytic Center on Microelectrode.

Biomimetic structures to fabricate bioelectronic interfaces that allow sensors to electrically communicate with electrodes have potential applications in the development of biosensors. Herein, inspired by the structure feature of nitric oxide (NO) sensory protein, we constructed a biomimetically catalytic center, the histamine coordinated iron phthalocyanine (FePc), for efficient and sensitive detection of NO. In specific, NO is recognized by axial tethered FePc, and the oxidative signal of NO on FePc is converted into output signal through electrocatalytic oxidation. Based on the fabricated catalytic structure on the carbon fiber electrode, on one hand, the macrocyclic π system of FePc enabled a rapid redox process, which facilitates electron transfer, thereby greatly improving sensitivity. On the other hand, by coordination with histamine on the electrode surface, FePc can enhance the electrochemical oxidation activity toward NO and promote catalytic detection, which have been revealed by electrochemical characterizations and density functional theory theoretical calculations. The designed electrochemical microsensor exhibits a low limit of detection (0.03 nM) and shows a wide detection range (0.1 nM-2 μM). In addition, the electrochemical microsensor has been successfully used for real-time monitoring of NO release by live cells. So, this work shows a new strategy for the design of bio-inspired electrochemical microsensors that may provide a potential analytical tool for tracing biological signal molecules with enzyme-free biomimetically catalytic centers.

FeCoNiMn/Ti electrode prepared by magnetron sputtering for efficient RhB degradation

Complex concentrated alloys (CCAs) with good catalytic performance have attracted considerable attention in dye wastewater treatment. However, there are few studies on CCAs as electrode materials for the electrochemical treatment of wastewater. In this work, FeCoNiMn thin film was deposited on a Ti substrate by direct current (DC) magnetron sputtering to obtain FeCoNiMn/Ti electrode. The composition and structure of the electrodes were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), high-resolution transmission electron microscope (HRTEM). Then Rhodamine B (RhB) was used as the model pollutant to evaluate the electrochemical oxidation activity and cycling stability of the electrode. The results show that the FeCoNiMn thin film is amorphous with a thickness of about 780 nm. RhB (10 mg/L) was almost completely degraded at a current density of 10 mA/cm2 within 270 min. Furthermore, the FeCoNiMn/Ti electrode could maintain the degradation ability of RhB in four consecutive cycles. The degradation mechanism of RhB was discussed and the failure cause of the electrode was analyzed in detail.

High-entropy (Oxy)hydroxide Prepared by Electrodeposition for Highly Efficient OER in Alkaline Medium

With the development of the economy and society, energy shortage and environmental pollution are increasingly in the spotlight. Electrolytic water to hydrogen technology is considered to be the best way to produce green hydrogen. However, the slow thermodynamic/kinetic limitations make it difficult to scale application due to an anodic oxygen evolution reaction (OER) involving four electrons. Recently, transition metal-based materials become popular research subjects because properties of abundant reserve and low cost. Fortunately, the performances for water splitting are surprising compared to some noble metal-based materials which means these materials have huge potential for practical application in reality. The transition metal (oxy)hydroxides are confirmed to be a category of promising electrocatalysts for OER. To improve the activity of catalysts, many effective strategies (including defects engineering, vacancy engineering, interface engineering, high-entropy effect, etc.) are adopted to modulate the electronic structure and enrich active site density. In this work, we have successfully synthesized high-entropy transition metal (oxy)hydroxides by one-step electrodeposition for water oxidation. The results obtained confirmed the high-entropy effect results in high intrinsic activity and high stability for electrochemical water oxidation.

Highly Dispersed Core–Shell Ni@NiO Nanoparticles Embedded on Carbon–Nitrogen Nanotubes as Efficient Electrocatalysts for Enhancing Urea Oxidation Reaction

Wastewater treatment and energy production are important fields of research to meet the current requirements of sustainable energy development and wastewater restoration. The urea oxidation reaction (UOR) can be used for simultaneous environmental remediation and energy production on a priority basis. Nickel–nickel oxide (Ni@NiO) core–shell NPs on carbon–nitrogen nanotubes (CNNTBs) have been synthesized as electrocatalysts by using a simple and easy aerial annealing method. Morphological analysis by high resolution-transmission electron microscopy (HR-TEM) confirms the formation of Ni@NiO NPs on CNNTBs with an average size of ∼40 nm. Powder X-ray diffraction (XRD) confirms Ni@NiOCN-X with a face-centered cubic (FCC) crystal structure. A BET surface area measurement suggests that annealing at 400 °C (Ni@NiOCN-4) creates a larger surface area than that of carbon–nitrogen material (CN). The electrochemical studies of the Ni@NiOCN-4 nanocomposite reveal that it has a better electrochemical activity and ultralow onset potential with an Eonset = 0.42 VAg/AgCl and current density of 34 mA/cm2 for a potential of 0.71 VAg/AgCl toward urea oxidation reactions. The annealing temperature-dependent studies were found to be effective toward the morphology tunning and hence tunable catalytic performance toward urea oxidation reactions. In urea oxidation studies, chronoamperometry (i–t) and EIS analysis show that the proposed Ni@NiOCN-4 system has long-term stability and ultrafast electron transfer. This work showed a simple way for temperature-dependent morphology tuning of a catalyst with enhanced electrochemical activity for urea oxidation, which is useful for sustainable energy production utilizing urea-rich wastewater.

One-pot preparation of NiMn layered double hydroxide-MOF material for highly sensitive electrochemical sensing of glucose

To rationally design and construct electrocatalytic nanomaterials is crucial for improving the sensitivity and selectivity of non-enzyme-based electrochemical sensors. Here, NiMn layered double hydroxide (LDH)-based MOF (NiMn-LDH-MOF) material was used as electrochemical electrode for highly sensitive assay of glucose. The NiMn-LDH-MOF was firstly synthesized by one-pot method via directly blending MOF-74, metal nodes and ammonia. The obtained NiMn-LDH-MOF has an excellent electrocatalytic activity for electrochemical oxidation of glucose and the NiMn-LDH-MOF/GCE sensor exhibits a wide linear detection range from 4.9 μM to 2.2 mM, a low detection limit (0.87 μM, S/N = 3), and high sensitivity (0.849 mA mM−1 cm−2). Meanwhile, the sensor has good selectivity and reliability for glucose detection in actual serum samples, suggesting the potential applicability of the sensor for glucose detection. The more exposed active sites, the introduction of LDHs subunit and the synergistic effect between Ni and Mn in the NiMn-LDH-MOF are the major factors to enhance the assay performance.

Accelerating Electrochemical Water Oxidation Activity by Tailoring Morphology and Electronic Structure of Nickel Organic Framework Nanoarrays with a Fe Etching Effect

Fe-mediated nickel organic framework nanoarrays (NiFe-MOFs NAs) on carbon cloth were successfully constructed from ultrathin nanosheets via an etching effect. This strategy also combined the dissolution and coordination effect of acidic ligand (2,6-naphthalenedicarboxylic acid, NDC) to a self-sacrificial template of Ni(OH)2 NAs. Benefiting from the strong Fe etching effect, dense and thick brick-like Ni-NDC nanoplates were tailored into loose and ultrathin NiFe-NDC nanosheets with abundant squamous nanostructures, which were still tightly attached to carbon cloth. As a consequence, more coordinatively unsaturated metal sites (CUMSs) that served as active centers were exposed to accelerate oxygen production. Meanwhile, the electronic structure of active Ni centers was modulated by the incorporation of Fe atoms. The charge density redistribution between Ni and Fe ultimately optimized the energy barrier of the adsorption/desorption of oxygenated intermediates, promoting the kinetics for water oxidation.

Highly sensitive non-enzymatic glucose sensor based on CoCu@MC derived from CoCu/melamine cyanurate superstructures

Non-enzymatic glucose detections have attracted more and more attentions with the development of electrochemical catalysts. Herein, Co2+ and Cu2+ are introduced into the hexagonal prism of melamine cyanurate, and nitrogen-doped carbon seaweed-like nanosheets ([email protected]) are synthesized through pyrolysis. [email protected] shows superior electrochemical catalytic activity for glucose oxidation with high sensitivity (1.489 μA μM−1 cm−2), low detection limit (0.34 μM) and wide linear range (1 μM–1.25 mM). Also, [email protected] demonstrates excellent application potential for glucose detection in artificial sweat with good conductivity, fast electron transfer, and high selectivity, which result from CoCu bimetal composites and seaweed-like carbon nanostructures. The glassy carbon electrode coated with [email protected] was used as the working electrode along with Ag/AgCl as the reference electrode and carbon rod as the counter electrode. The findings above will provide a general methodology to design and synthesize different carbon nanostructures through the addition of different transition metal cations.