Favorable Electrocatalytic Activity Research Articles

Cobalt nanoparticles intercalation coupled with tellurium-doping MXene for efficient electrocatalytic water splitting

Nowadays, the inherent re-stacking nature and weak d-p hybridization orbital interactions within MXene remains significant challenges in the field of electrocatalytic water splitting, leading to unsatisfactory electrocatalytic activity and cycling stability. Herein, this work aims to address these challenges and improve electrocatalytic performance by utilizing cobalt nanoparticles intercalation coupled with enhanced π-donation effect. Specifically, cobalt nanoparticles are integrated into V2C MXene nanosheets to mitigate the re-stacking issue. Meanwhile, a notable charge redistribution from cobalt to vanadium elevates orbital levels, reduces π*-antibonding orbital occupancy and alleviates Jahn-Teller distortion. Doping with tellurium induces localized electric field rearrangement resulting from the changes in electron cloud density. As a result, Co-V2C MXene-Te acquires desirable activity for hydrogen evolution reaction and oxygen evolution reaction with the overpotential of 80.8 mV and 287.7 mV, respectively, at the current density of −10 mA cm−2 and 10 mA cm−2. The overall water splitting device achieves an impressive low cell voltage requirement of 1.51 V to obtain 10 mA cm−2. Overall, this work could offer a promising solution when facing the re-stacking issue and weak d-p hybridization orbital interactions of MXene, furnishing a high-performance electrocatalyst with favorable electrocatalytic activity and cycling stability.

Hydrothermal synthesis of Cu2CoSnS4 nanoparticles: characterization and their applications of electrochemical, antibacterial and photocatalytic performances

Abstract A hydrothermal technique was used to successfully synthesize tetragonal Cu2CoSnS4 (CCTS) nanoparticles and investigate the effect of various thiourea concentrations on structural, morphological and optical properties. XRD analysis revealed the formation of tetragonal CCTS nanoparticles and the average crystallite size (nm) varied from 26 to 40 nm. The Raman studies confirmed the vibrational modes of the CCTS nanoparticles. The FE-SEM images revealed that the thiourea concentrations induced morphological changes in the CCTS nanoparticles, which exhibited the nanosheets changing into spherical structures. TEM images indicated that the CCTS sample had a spherical structure and the SAED pattern demonstrated a polycrystalline nature. The valance states of metallic species, such as Cu+ and Co2+ were further confirmed by XPS. The optical band gap (1.53 eV) was calculated from UV–Visible data and the obtained bandgap value from the literature. The electrochemical measurements of the CCTS TU-10 electrode exhibited pseudocapacitive behavior with a notable specific capacitance of 198 Fg−1 at a scan rate of 10 mV/S along with favorable electrocatalytic activity. In the photocatalytic application, when compared to MB dye (78 %), the CCTS catalyst was found to have a higher degradation efficiency toward CV dye (84 %). For antibacterial studies, the Vibrio parahaemolyticus bacteria exhibited the maximum zone of inhibition at 20 mm for 100 μg/ml. Finally, the experimental results suggested that the synthesized CCTS nanoparticles had better electrochemical, photocatalytic, and antibacterial properties.

One-step growth of RuNi-MOF nanoarrays on carbon felt host as a high-performance binder-free electrode for dual application: Ethanol fuel cell and supercapacitor

The future perspective is to develop high-efficient catalysts in next-generation energy technologies. Metal-organic frameworks (MOFs) offer a high degree of design flexibility which plays an important role as electrocatalysts. However, poor stability and low conductivity of MOFs are challenging to favorable electrocatalytic activity. Accordingly, a new and efficiently bimetallic RuNi-MOF is fabricated by in-situ growth of 3D nanoscale of MOFs on a 3D network of carbon felt (CF) to enhance the practical applicability of direct ethanol fuel cells (DEFCs) and supercapacitors (SCs). The RuNi-MOF/CF displays remarkable performance for SCs (the high specific capacitance of 1173.7 mF cm−2 (810.8 F g−1) at 6 mA cm−2, a high energy density of 145.9 Wh kg−1 and a power density of 6 kW kg−1 with cyclic retention of 95 %) and as an anode in DEFCs (peak current density of 84.6 mA cm−2 and power density of 70.2 mW cm−2 at 60 °C). The electron/ion transport ability and electrocatalytic performance of RuNi-MOF are enhanced due to the incorporation of Ru about 1.0 %. The success is attributed to the synergistic effects between Ru, Ni, and conductive CF. This work highlights a new understanding of using high-performance materials to improve electrocatalytic activity.

Electrochemical Determination of Homocysteine Using Self-Assembled 6-Ferrocenylhexanethiol on a Molybdenum Disulfide Nanoparticle Modified Glassy Carbon Electrode (GCE)

The determination of homocysteine (Hcy) is important because high levels are associated with a greater risk of developing heart disease or stroke. Herein, an electrochemical sensor of homocysteine was constructed based upon the self-assembly of 6-ferrocenylhexanethiol (FcC6SH) on a MoS2 nanoparticles-modified electrode with a Nafion coating. The sensor showed a favorable electrocatalytic activity for oxidation of homocysteine since 6-ferrocenylhexanethiol acted as a good electron transfer mediator. Moreover, the MoS2 nanoparticles served as modifiers to covalently immobilize FcC6SH and enhance the electrochemical active surface area. Highly sensitive determination of homocysteine was achieved with a linear range from 2.0 to 100 µmol L−1 and a minimum detectable concentration of 0.30 µmol L−1 by chronoamperometry. The constructed sensor was applied to the analysis of immunoglobulin G (IgG) samples with satisfactory results.

Nanoengineering of ZnCo2O4@CoMoO4 heterogeneous structures for supercapacitor and water splitting applications

A hybrid ZnCo2O4@CoMoO4 heterogeneous structure deposited onto nickel foam was synthesized via a two-step hydrothermal process. The results demonstrate that the hybrid architecture exhibits excellent electrochemical performance, including the specific capacitance of 1040C g−1 at 1 A g−1 for hybrid structures, high energy density of 87.3 Wh kg−1 at a power density of 2700 W kg−1 for an as-assembled supercapacitor and excellent cycle stability with a capacity retention of 99% undergoing 8000 charge-discharge for the device. Moreover, it also shows favorable electrocatalytic activity with low overpotentials of 237 mV at 20 mA cm−2 for oxygen evolution reaction and 114 mV at 10 mA cm−2 for hydrogen evolution reaction, and low cell voltage of 1.54 V at 10 mA cm−2 for overall water splitting. In addition, the stability maintains well for the long-term use of 13 h. We believe that this hybrid ZnCo2O4@CoMoO4 heterogeneous structure could be a promising candidate for future energy storage and conversion.

Polydopamine‐derived carbon layer anchoring NiCo‐P nanowire arrays for high‐performance binder‐free supercapacitor and electrocatalytic hydrogen evolution

AbstractTransition metal phosphides (TMPs) have been extensively and deeply researched as electrode materials for energy‐related applications. However, the inferior stability is still a bottleneck restricting their substantive development. Herein, a freestanding three‐dimensional hierarchical nanostructure (marked as CC@NC/NiCo‐P) is delicately designed for high‐performance supercapacitors and electrocatalytic hydrogen evolution, where the nitrogen‐doped carbon (NC) layer derived from polydopamine serves as an interface coupling bridge for anchoring electroactive nickel cobalt phosphide (NiCo‐P) nanowire arrays on flexible carbon cloth (CC) substrate. Thanks to the robust interaction between the conductive carbon support and NiCo‐P nanowires, the resultant CC@NC/NiCo‐P electrode delivers an ultrahigh capacitance (2175.5 F/g at 1 A/g) and a distinguished rate capability with a capacity retention of 85.8%. The assembled asymmetric supercapacitor can achieve a superior energy density of 28.47 Wh/kg and an ultralong lifespan of 10 000 cycles. In addition, the CC@NC/NiCo‐P electrode shows favorable electrocatalytic activity toward the hydrogen evolution reaction. These results indicate that the strong binding between the NC layer and metal species in TMPs notably improves the stability and electrochemical activity of CC@NC/NiCo‐P. It is expected that this effective strategy to design innovative electrode materials may be promising for the applications in energy‐related fields.

Dimethylimidazole and dicyandiamide assisted synthesized rich-defect and highly dispersed CuCo-Nx anchored hollow graphite carbon nanocages as efficient trifunctional electrocatalyst in the same electrolyte

This paper introduces a facile method to disperse rich-defect CuCo-N x active sites onto hollow graphite carbon nanocages, through one-pool dicyandiamide-assisted pyrolysis of porous CuCo-PBA-2MI precursor. The as-prepared CuCo-N x @N-CCs composites exhibit favorable electrocatalytic activity and robust durability for oxygen reversible catalysis (ORR/OER) and hydrogen evolution reaction (HER) in the same low concentration alkaline electrolyte (0.1 M KOH), including E ORR, 1/2 = 0.80 V, E OER, 10 = 1.58 V and E HER, 10 = −0.319 V. The nanocomposites show the superior electrocatalytic practical application in Zn-air batteries self-driven overall water splitting. Insights into the experimental analyses reveal that during the pyrolysis process, CuCo-PBA-2MI precursor captures volatile CN x active species from dicyandiamide, eventually forming high dispersed CuCo-N x active sites with unique N-doped porous hollow carbon scaffolds structure. Such hollow nanocage structures can effectively protect the active site from agglomeration and uneven distribution. It also prevents nanomaterials corrosion from alkaline electrolyte in the electrocatalytic reaction process. We believe that this strategy will offer useful guidelines to researchers who are interested in developing advanced and performance-oriented multifunctional electrocatalysts for clean energy devices. • Dimethylimidazole promoted the generation of hollow nanocage. • Dimethylimidazole acts as both a competitive ligand and a carbon/nitrogen source. • The dimethylimidazole and dicyandiamide make CuCo-N x active sites uniformly dispersed. • Unique hollow nanocage structure can prevent agglomerate and shedding of active sites. • CuCo-N x @N-CCs has excellent trifunctional electrocatalytic properties in same electrolyte.

A Dual-Functional Fibrous Skeleton Implanted with Single-Atomic Co-Nx Dispersions for Longevous Li-S Full Batteries.

Although lithium-sulfur (Li-S) batteries have long been touted as next-generation energy storage devices, the rampant dendrite growth at the anode side and sluggish redox kinetics at the cathode side drastically impede their practical application. Herein, a dual-functional fibrous skeleton implanted with single-atom Co-Nx dispersion is devised as an advanced modificator to realize concurrent regulation of both electrodes. The rational integration of single-atomic Co-Nx sites could convert the fibrous carbon skeleton from lithiophobic to lithiophilic, helping assuage the dendritic formation for the Li anode. Meanwhile, the favorable electrocatalytic activity from the Co-Nx species affording a lightweight feature effectively enables expedited bidirectional conversion kinetics of sulfur electrochemistry, thereby inhibiting the polysulfide shuttle. Moreover, the interconnected porous framework endows the entire skeleton with good mechanical robustness and fast electron/ion transportation. Benefiting from the synergistic effects between atomically dispersed Co-Nx sites and three-dimensional conductive networks, the integrated Li-S full batteries can achieve a reversible areal capacity (>7.0 mAh cm-2) at a sulfur loading of 6.9 mg cm-2. This work might be beneficial to the development of practically viable Li-S batteries harnessing single-atom mediators.

Structure-designed synthesis of hollow/porous cobalt sulfide/phosphide based materials for optimizing supercapacitor storage properties and hydrogen evolution reaction

Cobalt-based transition metal phosphides/sulfides have been viewed as promising candidates for supercapacitor (SCs) and hydrogen evolution reaction (HER) featured with their intrinsic merits. Nevertheless, the sluggish reaction kinetics and drastic volume expansion upon electrochemical process hinder their commercial application. In this work, the hollow/porous cobalt sulfide/phosphide based nanocuboids (C-CoP4 and CoS2 HNs) with superior specific surface area are achieved by employing a novel chemical etching-phosphatization/sulfuration strategy. The hollow/porous structure could offer rich active sites and shorten electrons/ions diffusion length. In virtue of their structural advantage, the obtained C-CoP4 and CoS2 HNs perform superior specific capacitance, fast charge/discharge rate and beneficial cycling stability. The advanced asymmetrical supercapacitors assembled by C-CoP4 and CoS2 HNs deliver exceptional energy density, respectively. Furthermore, when employed as hydrogen evolution reaction electrocatalysts, C-CoP4 and CoS2 HNs yield favorable electrocatalytic activity. These findings shed fundamental insight on the design of dual-functional transition metal phosphide/sulfide based materials for optimizing hydrogen evolution reaction and supercapacitor storage properties.

Ni3Fe nanoalloys embedded in N-doped carbon derived from dual-metal ZIF: Efficient bifunctional electrocatalyst for Zn-air battery

Developing non-noble oxygen electrocatalyst is of great importance in multiple energy conversion and storage technologies, for instance, metal-air battery, fuel cell and water electrolysis. Here, we report a bifunctional oxygen electrocatalyst derived from Ni–Fe dual-metal zeolitic imidazole frameworks, Ni3Fe nanoalloys embedded in N-doped carbon (Ni3Fe/N–C) containing carbon nanotube and porous carbon, which exhibits superior oxygen reduction and evolution reaction electrocatalytic performance. For oxygen reduction reaction, the onset potential and the half-wave potential of Ni3Fe/N–C are 0.92 V and 0.85 V, respectively, which are well consistent with those of commercial Pt/C. For oxygen evolution reaction, a low overpotential of 330 mV at 10 mA cm−2 is obtained for Ni3Fe/N–C, prominently better than that of commercial RuO2/C. Moreover, the oxygen reduction and evolution stability of Ni3Fe/N–C distinctly overmatches that of commercial Pt/C and RuO2/C. Benefiting from the favorable electrocatalytic activity and stability, the rechargeable Zn–air battery based on Ni3Fe/N–C exhibits smaller voltage gap (∼0.8 V) than the one based on commercial Pt/C and RuO2/C, and remarkable stability during 300-cycle discharge-charge test. The excellent performance can be attributed to the interaction between Ni3Fe nanoalloy and N-doped carbon, the unique nanostructure composed of carbon nanotube and porous carbons, and high graphitization degree.

Pulse Electrodeposition of a Superhydrophilic and Binder-Free Ni-Fe-P Nanostructure as Highly Active and Durable Electrocatalyst for Both Hydrogen and Oxygen Evolution Reactions.

Development and fabrication of electrodes with favorable electrocatalytic activity, low-cost, and excellent electrocatalytic durability are one of the most important issues in the hydrogen production area using the electrochemical water splitting process. We use the pulse electrodeposition method as a versatile and cost-effective approach to synthesize three-dimensional Ni-Fe-P electrocatalysts on nickel nanostructures under various applied frequencies and duration times, in which nanostructures exhibit excellent intrinsic electrocatalytic activity. Benefiting from the three-dimensional structure, as well as the simultaneous presence of the three elements nickel, iron, and phosphorus, the electrode fabricated at the optimal conditions has indicated outstanding electrocatalytic activity with a η10 of 66 and 198 mV for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively, in a 1.0 M KOH solution. Also, the water electrolysis cell constructed with this electrode and tested as a bifunctional electrode exhibited 1.508 V for 10 mA cm-2 in overall water splitting. In addition, the lowest amount of potential change in 100 mA cm-2 was observed for HER and OER, indicating excellent electrocatalytic stability. This study proposes a binder-free and economical technique for the synthesis of three-dimensional electrocatalysts.

An efficient and durable perovskite electrocatalyst for oxygen reduction in solid oxide fuel cells

Achieving superior electrocatalytic activity and thermal/chemical stability of cathode materials is the key to high-performance and durable solid oxide fuel cells (SOFC). Here, we present a barium and praseodymium co-substituted perovskite Bi0.7Pr0.1Ba0.2FeO3-δ (BPBF), a cubic-symmetry oxide phase, as a candidate cathode material for SOFC, with a focus on its crystalline structure, oxygen transport, electrocatalytic activity, as well as structural and chemical stability. The BPBF-based cathode delivers superior electroactivity, with a polarization area-specific-resistance as low as 0.056 Ω cm2 at 700 °C in symmetrical cells. Surprisingly, when exposed to both air and 1 vol% CO2-containing air at 600 °C for 100 h, the electrode activity remains constant. The prominent thermal and chemical (CO2 tolerance) stability can be ascribed to co-substitution of barium and praseodymium and high acidity of bismuth ions. Endowed with favorable electrocatalytic activity and excellent durability, the BPBF-based material can be a promising cathode to facilitate commercialization of SOFC technology.

3D pothole-rich hierarchical carbon framework-encapsulated Ni nanoparticles for highly selective nonenzymatic cysteine detection

3D pothole-rich hierarchical amorphous carbon network-encapsulated Ni nanoparticles (Ni NPs) electrocatalytic material (3D-Ni@AC) is successfully designed and synthesized via a facile in-situ NaCl template-removal method for electrochemical non-enzymatic cysteine (CySH) detection. 3D-Ni@AC assembled from the carbon nanosheet encapsulated Ni NPs layer-by-layer interlaced possesses interconnected porous network structure, the network structure of carbon nano-layer can effectively prevent the agglomeration of Ni NPs, ensuring full utilization of active materials. Cyclic voltammetric (CV) study showed that 3D-Ni@AC/GCE displayed high electrocatalytic activity toward the oxidation of CySH compared to template-free Ni@AC/GCE. The unique structure, the enlarged specific surface area and the synergistic effects from the excellent conductivity of carbon frame and Ni NPs provide fast electrons/ions transfer and favorable electrocatalytic activity for the electro-oxidation of CySH. In an electrolyte solution of 0.1 M NaOH, the constructed CySH sensor offered a high sensitivity (0.079 mA/cm2 μM), a low detection limit (0.15 μM) and a wide linear range (from 0.8 to 85 μM). The fabricated high electrocatalytic performance sensor was utilized to monitor the CySH levels in urine and serum, and satisfactory results were gained. Moreover, 3D-Ni@AC electrode showed good reproducibility, stability, and anti-interference ability, indicating that 3D-Ni@AC can be used as a good electrocatalytic material in practical biological applications.

Defect-rich hexagonal boron nitride for the simultaneous determination of 4-aminophenol and phenol

A new electrochemical sensor has been developed for the simultaneous determination of 4-aminophenol (4-AP) and phenol (Ph) based on the defect-rich hexagonal boron nitride (D-h-BN). The D-h-BN was prepared via one-step calcination route using a single-source precursor. The obtained D-h-BN was structurally characterized by X-ray diffraction (XRD), fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM). Photoluminescent (PL) result suggested that the as-synthesized h-BN was highly defective. More interestingly, such D-h-BN exhibited favorable electrocatalytic activity in the redox reaction of Ph and 4-AP, which was confirmed by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) measurements. The enhanced electrocatalytic activity of D-h-BN was attributed to its large surface-active sites and fast electron transfer mediated by defect structure. Thus, D-h-BN was employed to modify glassy carbon electrode (GCE) without any binder agents and the as-fabricated sensor showed good electrochemical performances in the simultaneous determination of 4-AP and Ph. By using DPV method, the linear detection ranges between concentrations and current intensities for 4-AP and Ph were 0.01–30 and 0.1–30 μM, respectively, and their detection limits (S/N = 3) were estimated to be 0.003 and 0.035 μM. Moreover, the desirable selectivity and reproducibility make the proposed method successfully applied for real sample assay.

Enhanced photovoltaic performance of dye-sensitized solar cells based on electrodeposited sulfur-doped MSex (M=Co, Ni) films

Rational design of ternary transition metal sulfoselenide films by an electrodeposition technique remains a critical challenge to further improve their catalytic activity. This study reports a fabrication approach of sulfur-doped MSex (M = Co, Ni) films, which are directly employed as efficient counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). The morphology and electronic structure of sulfur-doped MSex films are controlled by adjusting the molar ratio of S/Se in their electrodeposition solutions. It is found that sulfur-doped MSex films exhibit favorable electrocatalytic activity for the reduction of I3−, owing to their more exposed activity sites and strong charge-transfer capability. Furthermore, the DSSC fabricated with the optimized sulfur-doped CoSex (sulfur-doped NiSex) CE has achieved the highest power conversion efficiency (PCE) of 7.44% (7.54%) than that of the DSSC fabricated with platinum (Pt) CE (6.38%). The results demonstrate that sulfur-doped MSex films have been applied as the attractive low-cost CEs with outstanding electrocatalytic activity for DSSCs.

A facile method to conduct 3D self-supporting Co-FeCo/N-doped graphene-like carbon bifunctional electrocatalysts for flexible solid-state zinc air battery

The rapid development of wearable and portable electronics is triggering a lot of researches on flexible energy device. Flexible zinc-air batteries (ZABs) with high bifunctional oxygen electrocatalytic activity and superb flexible can be employed as promising power supplies to fulfill these novel electronic devices. Considering the major challenges to the flexible ZABs such as low power density, poor energy efficiency and unsatisfactory mechanical stability, we propose a novel plasma-assistance strategy to prepare highly foldable self-supporting air-electrodes based on nitrogen-doped carbon layer encapsulated Co and FeCo nanoparticles hybrid nanowire arrays (Co-FeCo/N-G). The obtained Co-FeCo/N-G air-electrode show superior oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) activity. Thus, the flexible ZABs using Co-FeCo/N-G air-electrode achieve a high open circuit voltage of 1.419 V. Furthermore, it exhibits an outstanding peak power density of 82 mW cm−2, a small discharge-charge voltage gap of 0.61 V at 1 mA cm−2 and long-term durability. Specially, the flexible Co-FeCo/N-G ZAB displays excellent mechanical stability under large deformation conditions, which can be folded into 180° without obvious decay of its performance. Thereby, our work offers a unique insight into design of highly flexible air electrodes with favorable electrocatalytic activity for emerging wearable and portable electronics.

CuNCo3-Xvx Antiperovskite As a High Performance Catalyst for Oxygen Evolution Reaction

Oxygen evolution reaction (OER) has drawn particular attention due to its important role for various energy generation and storage application, such as water splitting, rechargeable metal-air batteries and regenerative fuel cells. However, the intrinsically sluggish kinetic caused by multi proton-couple electron transfer steps, makes the OER inefficient on these applications. To promote the overall energy storage and generative efficiency, it is indispensable to develop highly efficient electrocatalyst for OER. Up to now, the noble-metal oxides (e.g. IrO2 and RuO2) are still considered as the best electrocatalysts for OER. Nevertheless, the high cost and scarcity of the involved precious metal have greatly limited their applications. Therefore, it urgently requires to seek the highly efficient OER catalysts that are cost-effective and earth-abundant. In the past decades, the perovskite oxides (ABO3, where A is rare or alkaline earth metal element and B is transition metal element) have been considered as an alternative OER catalyst for their low cost and intrinsically desirable OER activities. These oxides possess sufficient combination between different transition metal, which enables the highly synergic effect for their electrocatalysis. Also, the A site or B site can be partially substituted by other transition metal. This structural flexibility can arise the enhancement of the activity and stability of the perovskite oxides. However, the perovskite-based OER catalysts usually suffer poor conductivity at the applied temperature. To solve this problem, a widely used strategy is to combine metal oxides with high-surface-area carbon supports. It’s notable that metal oxide/carbon hybrid catalysts are unstable, especially under the condition of oxygen evolution reaction, because the oxidation of carbon occurs at low potentials (equilibrium potential of 0.207 V vs. the reversible hydrogen electrode (RHE). Transition metal nitrides are very attractive as robust supports and electrocatalysts because they have a number of desirable properties such as high electrical conductivity. Some antiperovskite nitride such as InNNi3 have been considered as the superconductive materials. More interestingly, the antiperovskite nitrides (ANM3, A and M represent different transition metal, respectively) share the similar perovskite structure with the perovskite oxides. Moreover, the perovskite structure of antiperovskite nitrides may enable the ANM3 to achieve structural flexibility as the corresponding effects have been verified by the previously reported materials (e.g. CdNCo3-zNiz (0  z 3) and Cd1−xInxNNi3 (0  x  0.2)). The tunable structure of the ANCo3 can offer much potential for the optimization of its electrocatalytic activity. Herein, we report an antiperovskite-based CuNCo3-xVx (0  x < 1) nitride as a high-performance OER catalyst exhibiting favorable electrocatalytic activity and stability. The experimental results reveal that the CuNCo3 exhibits highly intrinsic OER performance compared to Co4N. And the structural flexibility of the antiperovskite CuNCo3 also has been verified by the partially substituting the Co sites with V. The derived CuNCo2.4V0.6 can achieve an impressive enhancement with an overpotential of merely 242 mV to reach the current density of 10 mA cm-2. The time-dependent potential measurement and zinc-air batteries test also suggested its superior durability compared to Ir/C catalyst. Density of states (DOS) indicates the partial substitution of Co by V results in the negative shift of the d band center near the Fermi level for CuNCo3, which would weaken the interaction between the adsorbates and the OER catalyst and facilitate the OER process.

Metal-organic-framework-derived formation of Co–N-doped carbon materials for efficient oxygen reduction reaction

Abstract Non-precious metal nitrogen-doped carbonaceous materials have attracted tremendous attention in the field of electrochemical energy storage and conversion. Herein, we report the designed synthesis of a novel series of Co-N-C nanocomposites and their evaluation of electrochemical properties. Novel yolk-shell structured Co nanoparticles@polymer materials are fabricated from the facile coating polymer strategy on the surface of ZIF-67. After calcination in nitrogen atmosphere, the Co–N–C nanocomposites in which cobalt metal nanoparticles are embedded in the highly porous and graphitic carbon matrix are successfully achieved. The cobalt nanoparticles containing cobalt metal crystallites with an oxidized shell and/or smaller (or amorphous) cobalt-oxide deposits appear on the surface of graphitic carbons. The prepared Co–N–C nanoparticles showed favorable electrocatalytic activity for oxygen reduction reactions, which is attributed to its high graphitic degree, large surface area and the large amount existence of Co–N active sites.

Co-synthesis of CuO-ZnO nanoflowers by low voltage liquid plasma discharge with brass electrode

Transition metal oxides CuO-ZnO nano-flowers have been simultaneously synthesized by the low voltage liquid plasma discharge method using brass cathode. The effects of discharge statue (normal and abnormal glow discharge) on the nanostructures were investigated. It was found that a lower discharge voltage 52 V in the normal glow discharge period is beneficial to produce homogeneous nano-flower structures while a higher voltage tend to result in inhomogeneous products including larger particles. The obtained products were characterized by SEM, XRD, high-resolution TEM, Raman and XPS. Moreover, the nano-flowers exhibit a favorable electrocatalytic activity of glucose oxidation.

Multi-modal tracking dopamine using a hybrid inorganic-organic silver nanoparticle and its cellular imaging performance

A novel strategy to highly sensitize terbium luminescence through 3-carboxyphenylboronic acid as the antenna ligand has been realized and the hybrid inorganic-organic probe has been assembled based on the silver nanoparticles. Its green emission is turned off in the presence of dopamine and the detection process is within 2–3 s. Cyclic voltammetry curves showed that a glassy carbon electrode modified with this lanthanide nanostructure demonstrated favorable electrocatalytic activity for the oxidation of dopamine in phosphate buffer. The developed nanosensor gave rise to a linear correlation depending on dopamine concentration and the detection limit was determined to be 0.41 μM. This dual-modal (optical and electrochemical) probe exhibited excellent selectivity and enough stability. The feasibility of the terbium sensitized nanosensor for cellular imaging has also been reported. Two adherent cell lines (Hela cells and THP-1 cells) exposed to the nanoprobe demonstrated striking green luminescence and showed on-off changes in the regulation of dopamine.