Superior Electrochemical Behavior Research Articles

Synthesis, characterization and evaluation of new alternative ruthenium complex for dye sensitized solar cells

For first time, new innovative ruthenium N3-Dye anchored with selenium (Se) and N3 dye anchored with sulphur atoms were synthesized in a good yield. Dyes are applied and evaluated in performance of dye sensitized solar cell. N3–Se dye showed superior photochemical& electrochemical behavior and high rate electron transfer across anode surface than N3–S dye. The better optical and electrochemical activities would make Se-dye a candidate for applications in solar cells. Half life time of N3–S showed a single exponential decay with an average lifetime of 0.8 ns. For N3–Se dye, decay curve was fitted by sum two exponential functions with 75% and 25% counts have 2.5 ns and 30 ns respectively. Solar cells were fabricated and analyzed to determine their solar-to-electric conversion efficiency under standard AM 1.5 sunlight. Commercial N3 dyes showed current density (Jsc) of 17.813 mA cm−2, open circuit potential (Voc) of 0.678 V, filling factor (FF) of 0.607 and conversion efficiencies (η) of 7.3%. Corresponding values for N3–S dye, Jsc 11.2 mA cm−2, Voc 0.650 V, FF 0.681 and η 5%. Se–N3 dye, showed Jsc = 6.670 mA cm−2, Voc = 0.6004 V, FF = 0.77 and η = 3.09%. Long lifetime of N3–Se caused low practical performance.

Effect of protein adsorption on hyaluronic acid/curcumin/multi-walled carbon nanotube based electrochemical sensor for detection of dopamine

Resisting protein adsorption on electrode surfaces is one of pivotal challenges in the electrochemical analysis of small bioactive molecules. In this work, we constructed a novel electrochemical sensing electrode modified with hydrophilic hyaluronic acid (HA) and curcumin/multi-walled carbon nanotube (CM/MWCNTs). The modified electrodes were comprehensively characterized for dopamine detection including the sensing sensitivity, selectivity and stability. The constructed electrochemical sensor for dopamine detection exhibited remarkable resistance to protein adsorption because of the inherent hydrophilicity of HA, and synergistically, the superior electrochemical behavior of the CM/MWCNTs composite (quinone/hydroquinone redox couples enabled superior electrochemical behavior). The HA/CM/MWCNTs/GCE performed about 5.0 folds, 3.5 folds and 2.4 folds higher electrocatalytic current for dopamine than that revealed at bare GCE, MWCNTs/GCE, and CM/MWCNTs/GCE, respectively. In addition, the HA/CM/MWCNTs-based sensor demonstrated excellent sensing performance with a low detection limit of 0.009 μM (S/N = 3) within the concentration range from 50 to 200 μM. The constructed HA/CM/MWCNTs-modified glassy carbon electrodes offered a reliable platform for the real-time monitoring of dopamine with no protein absorption.

Augmented surface terminations on few-layer MXene (Ti3C2Tx) with superior electrochemical behavior for energy storage applications

Augmented surface terminations on few-layer MXene (Ti3C2Tx) with superior electrochemical behavior for energy storage applications

Synthesis of BiDy composite oxide nanoflakes with good electrochemical properties

Bismuth dysprosium (BiDy) composite oxide nanoflakes with a thickness of about 50 nm were synthesized using a one-step hydrothermal method. Electrodes modified with BiDy composite oxide nanoflakes exhibited a superior electrochemical behavior for detecting l-cysteine using the cyclic voltammetry (CV) method. The impacts of scan rate, electrolyte and concentration of l-cysteine on electrochemical behaviors were investigated. A pair of strong quasi-reversible CV peaks was observed at +0.03 V (cvp1) and −0.69 V (cvp1′) with peak currents of 171.2 and 171.3 μA, respectively, for a BiDy-composite-oxide-nanoflake-modified glassy carbon electrode (GCE) in 0.1 M potassium chloride (KCl) and 2 mM l-cysteine solution. The GCE modified with BiDy composite oxide nanoflakes displayed a broad range of linearity (0.001–2 mM) and a low detection limit (0.29 μM) for l-cysteine. Using a hydrothermal approach as a synthesis technique for nanoflakes, a facile and sensitive electrochemical sensor based on nanoflakes was developed for detecting l-cysteine, making it a promising approach for practical application.

Construction of a nanostructured NiCo2S4/Ni/Ni9S8 composite for energy storage applications

It is necessary to investigate and develop nickel-cobalt sulfide electrodes with superior electrochemical behavior. This work produced the NiCo2S4/Ni/Ni9S8 nanostructure composite (NCS/N/NS) for energy storage in supercapacitors using a solvothermal technique with polyethyleneimine (PEI) as a carbon source, followed by an hour of annealing in an argon atmosphere, and a hydrothermal method with thiourea as a sulfur and nitrogen source. Outstanding electrochemical energy storage properties are provided by NCS/N/NS. The produced electrode material, NCS/N/NS, demonstrated an exceptional capacitance of 1620 F g−1 (696 C g−1) at 1 A g−1 when employed for SCs. An NCS/N/NS was used as the positively charged electrode and the opposite electrode of commercial AC to build an NCS/N/NS//activated carbon (AC) asymmetric device for practical usage. At 1 A g−1, the asymmetric device produced a specific power of 887 W kg−1 and a unique specific energy of 53 Wh kg−1. Moreover, it exhibits a 100% coulombic efficacy and a 95% capacity retention after 3000 cycles, respectively.

Recent Advances in the Synthesis of Conjugated Polymers for Supercapacitors

AbstractConjugated polymers have attracted growing attention for versatile applications in energy storage due to their potential benefits including low‐cost processing, molecular tunability, environmental benignity, and high mechanical flexibility. In particular, polymer‐based organic electrode materials have shown significant progress in supercapacitor (SC) applications with superior electrochemical behaviors. The performances of SCs are closely related to the intrinsic characteristics of different polymers in the nanoscale and the morphological features of the polymer‐based electrode materials obtained by different fabrication techniques in the macroscale. This review summarizes the design and synthesis of both p‐type and n‐type conjugated polymers, highlighting the pros and cons of three synthesis techniques: electrochemical polymerization, chemical polymerization, and in situ polymerization. The performances of conjugated polymers in SCs, their cycling stabilities, and structure‐performance relationships are discussed. Moreover, the existing challenges and future directions of polymer‐based SCs are considered with respect to energy density, stability, and large‐scale production to promote commercialization.

High-performance Ni-free sustainable cathode Na0.67Mg0.05Fe0.1Mn0.85O2 for sodium-ion batteries.

Having in mind the remarkable economic and environmental issues involved in the presence of nickel and cobalt metals in electrode compositions, new Na0.67Mg0.05Fe0.1NixMn0.85-xO2 (x=0.0, 0.05, 0.1, 0.15) with a P2 type layered structure, are synthesized to be essayed as positive electrodes in sodium-ion batteries. The sol-gel route here proposed favors the obtention of highly pure and crystalline samples with a homogeneous distribution of the constituting elements. Both galvanostatic and voltammetric tests reveal a superior electrochemical behavior for the Ni-free sample, which delivers 94 mA h g-1 at 5C. This excellent performance is associated with a good kinetic response in terms of low charge and discharge hysteresis, high Na+ diffusivity, and low cell resistance. Ex-situ measurements evidenced the combined contribution of both the reversible electrolyte insertion and the formation of peroxo species. These advantageous properties allow this electrode to reach a remarkable behavior when is cycled either to low temperatures or high rates.

Consecutive engineering of anodic graphene supported cobalt monoxide composite and cathodic nanosized lithium cobalt oxide materials with improved lithium-ion storage performances

Downsizing the electrochemically active materials in both cathodic and anodic electrodes commonly brings about enhanced lithium-ion storage performances. It is particularly meaningful to explore simplified and effective strategies for exploiting nanosized electrode materials in the advanced lithium-ion batteries. In this work, the spontaneous reaction between few-layered graphene oxide (GO) and metallic cobalt (Co) foils in mild hydrothermal condition is for the first time employed to synthesize a reduced graphene oxide (RGO) supported nanosized cobalt monoxide (CoO) anode material (CoO@RGO). Furthermore, the CoO@RGO sample is converted to nanosized lithium cobalt oxide cathode material (LiCoO2, LCO) by taking the advantages of the self-templated effect. As a result, both the CoO@RGO anode and the LCO cathode exhibit inspiring lithium-ion storage properties. In half-cells, the CoO@RGO sample maintains a reversible capacity of 740.6 mAh·g−1 after 300 cycles at the current density of 1000 mA·g−1 while the LCO sample delivers a reversible capacity of 109.1 mAh·g−1 after 100 cycles at the current density of 100 mA·g−1. In the CoO@RGO//LCO full-cells, the CoO@RGO sample delivers a reversible capacity of 553.9 mAh·g−1 after 50 cycles at the current density of 200 mA·g−1. The reasons for superior electrochemical behaviors of the samples have been revealed, and the strategy in this work can be considered to be straightforward and effective for engineering both anode and cathode materials for lithium-ion batteries.

Designing F/P Hybrid Polymer as Ultrastable Cationic Shielding Interphase for High-Performance Lithium Metal Batteries.

Dendrite growth on electrode-electrolyte interphase has severely limited applications of lithium metal batteries (LMBs). Here, we developed an ionic alternating polymer with fluorocarbons and phosphonium cations in repeating units to regulate Li deposition for the first time. The combined functionalities in the F/P hybrid polymer exhibit remarkable characteristics as a protective layer on top of Li anode, demonstrating outstanding electrochemical stability, ion flux redistributing capability and adaptive chain mobility. Based on characterizations and simulations, this cationic interlayer could effectively furnish long-standing electrostatic shielding for anodes, allowing restrained coating decomposition and homogenized electric field distribution to induce dendrite-free Li deposition, and enabling full cells with enhanced rate and long-term cycling performance. Given the importance of LMBs, this work will promote polymer design to stabilize anodes with superior electrochemical behavior.

Designing F/P Hybrid Polymer as Ultrastable Cationic Shielding Interphase for High‐Performance Lithium Metal Batteries

AbstractDendrite growth on electrode‐electrolyte interphase has severely limited applications of lithium metal batteries (LMBs). Here, we developed an ionic alternating polymer with fluorocarbons and phosphonium cations in repeating units to regulate Li deposition for the first time. The combined functionalities in the F/P hybrid polymer exhibit remarkable characteristics as a protective layer on top of Li anode, demonstrating outstanding electrochemical stability, ion flux redistributing capability and adaptive chain mobility. Based on characterizations and simulations, this cationic interlayer could effectively furnish long‐standing electrostatic shielding for anodes, allowing restrained coating decomposition and homogenized electric field distribution to induce dendrite‐free Li deposition, and enabling full cells with enhanced rate and long‐term cycling performance. Given the importance of LMBs, this work will promote polymer design to stabilize anodes with superior electrochemical behavior.

Synthesis of hierarchical binary core‐branch nanocomposite of carbon microspheres@α‐Fe2O3 for enhancing electrochemical behavior

AbstractA facial strategy for the synthesis of hierarchical binary core‐branch carbon microspheres (CMS)@α‐Fe2O3 is presented. X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FT‐IR), energy‐dispersive X‐ray spectroscopy (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high‐resolution TEM (HR‐TEM), and Brunauer–Emmett–Teller (BET) were used to characterize the structural and morphological properties of the products. XRD diffraction analysis of CMS@α‐Fe2O3 reveals the highly crystalline nature of α‐Fe2O3 in the hierarchical binary core‐branch CMS@α‐Fe2O3 nanocomposite. Morphological analyses show that the α‐Fe2O3 shell layer grew onto the surface of CMS to form nanoscale heterointerfaces in the core‐branch structure, demonstrating the effectiveness of the synthesized route. More importantly, CMS@α‐Fe2O3 demonstrated superior electrochemical behavior to CMS. The enhanced CMS@α‐Fe2O3 electrochemical performance can be attributed to its large specific surface area, which allows for the rapid transfer of electrons into the electrode during the redox process.

Application of purified kish flake graphite as a potential cathode material for high-performance aluminum ion batteries

The separation and purification of kish graphite is an important prerequisite for its high value and comprehensive utilization. The comprehensive separation process including water washing dust removal, magnetic separation and acid leaching purification can effectively enrich and purify kish flake graphite (KFG) from low-cost industrial by-product kish graphite. When the magnetic strength is 2000 Gauss, the purified KFG has suitable recovery (57.34%), high fixed carbon content (99.38%) and low ash content (0.62%). Compared with natural flake graphite, KFG has a highly ordered graphite microcrystalline layer structure with higher graphitization degree (99.77%) and well-developed micro/nanopore with larger specific surface area (4.12 m2·g−1). Such distinctive microstructure features ensure KFG to be applied as a cathode material for aluminum ion batteries (AIBs) to exhibit superior electrochemical behaviors. KFG exhibits a high reversible specific capacity (110.7 mAh/g at 50 mA/g), outstanding rate capability (56.9 and 26.6 mAh/g at high current densities of 1000 and 2000 mA/g) and superior long-term cycling stability (101.8 mAh/g with a Coulombic efficiency of 99.5% at 1000 mA/g after 2000 cycles). This study demonstrates a promising feasibility for mass production of KFG from industrial by-product kish graphite for high performance AIBs.

Nanocomposites with ZrO2@S-Doped g-C3N4 as an Enhanced Binder-Free Sensor: Synthesis and Characterization.

This study describes new electrocatalyst materials that can detect and reduce environmental pollutants. The synthesis and characterization of semiconductor nanocomposites (NCs) made from active ZrO2@S-doped g-C3N4 is presented. Electrochemical impedance spectroscopy (EIS) and Mott-Schottky (M-S) measurements were used to examine electron transfer characteristics of the synthesized samples. Using X-ray diffraction (XRD) and high-resolution scanning electron microscopy (HR-SEM) techniques, inclusion of monoclinic ZrO2 on flower-shaped S-doped-g-C3N4 was visualized. High-resolution X-ray photoelectron spectroscopy (XPS) revealed successful doping of ZrO2 into the lattice of S-doped g-C3N4. The electron transport mechanism between the electrolyte and the fluorine tin-oxide electrode (FTOE) was enhanced by the synergistic interaction between ZrO2 and S-doped g-C3N4 as co-modifiers. Development of a platform with improved conductivity based on an FTOE modified with ZrO2@S-doped g-C3N4 NCs resulted in an ideal platform for the detection of 4-nitrophenol (4-NP) in water. The electrocatalytic activity of the modified electrode was evaluated through determination of 4-NP by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) under optimum conditions (pH 5). ZrO2@S-doped g-C3N4 (20%)/FTOE exhibited good electrocatalytic activity with a linear range from 10 to 100 μM and a low limit of detection (LOD) of 6.65 μM. Typical p-type semiconductor ZrO2@S-doped g-C3N4 NCs significantly impact the superior detection of 4-NP due to its size, shape, optical properties, specific surface area and effective separation of electron-hole pairs. We conclude that the superior electrochemical sensor behavior of the ZrO2@S-doped g-C3N4 (20%)/FTOE surfaces results from the synergistic interaction between S-doped g-C3N4 and ZrO2 surfaces that produce an active NC interface.

Ultrathin MoS2 nanosheets grown on hollow carbon spheres as advanced separator coating for superior electrochemical behaviors of Li–S batteries

Ultrathin MoS2 nanosheets grown on hollow carbon spheres as advanced separator coating for superior electrochemical behaviors of Li–S batteries

Reduced Potential Barrier of Sodium-Substituted Disordered Rocksalt Cathode for Oxygen Evolution Electrocatalysts.

Cation-disordered rocksalt (DRX) cathodes have been viewed as next-generation high-energy density materials surpassing conventional layered cathodes for lithium-ion battery (LIB) technology. Utilizing the opportunity of a better cation mixing facility in DRX, we synthesize Na-doped DRX as an efficient electrocatalyst toward oxygen evolution reaction (OER). This novel OER electrocatalyst generates a current density of 10 mA cm-2 at an overpotential (η) of 270 mV, Tafel slope of 67.5 mV dec-1, and long-term stability >5.5 days' superior to benchmark IrO2 (η = 330 mV with Tafel slope = 74.8 mV dec-1). This superior electrochemical behavior is well supported by experiment and sparse Gaussian process potential (SGPP) machine learning-based search for minimum energy structure. Moreover, as oxygen binding energy (OBE) on the surface closely relates to OER activity, our density functional theory (DFT) calculations reveal that Na-doping assists in facile O2 evolution (OBE = 5.45 eV) compared with pristine-DRX (6.51 eV).

High Electrochemical Performance of a Nanostructured Electrode Material Based on a Cobalt-Manganese Layered Double Hydroxide

In this work, alpha-cobalt hydroxide (Co(OH)2) and cobalt/manganese layered double hydroxide (CoMn-75-LDH) were synthesized using the Tower method. The alpha phase was confirmed for Co(OH)2 through XRD analysis. Furthermore, the TEM images showed that the materials are formed by nanoparticles with an average size of ~5 nm. Cyclic voltammetry and galvanostatic charge/discharge measurements were carried out and the CoMn-75-LDH presented a superior electrochemical behavior to Co(OH)2. The presence of Mn2+/3+ ions in the crystal structure of CoMn-75-LDH, verified by XPS analysis, enhanced the electrical conductivity of the material, providing more electroactive sites, as a result, the electrochemical performance of the material was improved. Electrochemical studies showed that CoMn-75-LDH has a specific capacitance of 677 F g-1 at current density of 0.5 A g-1 compared to Co(OH)2, whose specific capacitance value was 268.7 F g-1 at the same current density. In addition, the electrochemical signature of Co(OH)2 revealed that the electrode material exhibits an extrinsic pseudocapacitive behavior instead of the typical behavior of battery-type materials due to its nanostructured morphology. Also, electrochemical studies showed that the charge storage mechanism for CoMn-75-LDH is controlled by both the capacitive and diffusion process.

Enhanced electricity generation and storage by nitrogen-doped hierarchically porous carbon modification of the capacitive bioanode in microbial fuel cells

Microbial fuel cells (MFCs) can potentially be utilized for power generation, but their low power density and low energy storage capabilities remain major bottlenecks for their large-scale development. In this research, a simplistic nitrogen-doped hierarchically porous carbon material (HPC-A) was developed through a one-step carbonization and activation process and was successfully hot-pressed on the carbon cloth (CC) substrate. This process fabricates capacitive bioanodes (HPC-A-CC) that can enhance electricity generation and storage in MFCs. The as-prepared HPC-A-CC anode delivered a power density of 2043.6 mW·m−2 and a cumulative total charge (Qm) of 426.4 ± 13.4C·m−2 at each cycle, which was 2.1 and 34.8 times higher than that of the plain CC anode, respectively. This was a result of the hierarchical and interconnected porous structure, improved hydrophilic surface, and increased number of active centers which host the bacteria for enhanced electron transfer. Electrochemical measurements indicated the superior electrochemical activity and capacitive behavior of the HPC-A-CC anode. Furthermore, biofilm analysis revealed that the HPC-A-CC biofilm exhibited higher cell viability and a more uniform spatial distribution. These findings not only demonstrate the potential of HPC-A-CC for power enhancement in MFCs but also provide a feasible solution to the problem of power generation and demand mismatch in MFC applications.

Printed Graphite Electrodes for Fast Charging Lithium-Ion Batteries

Fast charging capability has become one of the key features of lithium-ion batteries (LIBs) to facilitate the rapid growth of the electric vehicle (EV) market. However, charging thick electrodes in conventional EV batteries at high current densities always leads to adverse battery performance and safety issues. To address these challenges, thick graphite electrodes with patterned porous architecture were developed through a facile printing process. With selected graphite and developed formula, an appropriate graphite ink was printed onto the copper foil through the screen printing with designed patterned pore channels. The porous structure including pore diameter and pore-to-pore distance was controlled via adjusting the designed patterns on the screens. The presence of porous structure was confirmed through microscopic images. The printed graphite electrodes exhibited superior electrochemical behaviors over traditional electrodes in terms of rate capability and cycle life. It is believed that the improved battery performance is associated with the improved Li-ion transport arising from the patterned porous structure in printed electrodes. Results from the electrochemical impedance spectroscopy (EIS) indicate that, compared with traditional electrodes without patterned pores, printed electrodes have significantly reduced tortuosity. The post-mortem analysis of cycled cells demonstrates that the printed electrodes have the capability to suppress the Li plating related to fast charging rates. Combining with the advantages of low cost and high throughput, the printed electrode with patterned pores, thus, has the potential of replacing conventional electrodes in commercial LIBs to realize the fast-charging application. Keywords: Graphite, Printing, Fast charging, Li-Ion Batteries

Architecturally robust tubular nano-clay grafted Li0.9Ni0.5Co0.5O2-x/LiFeO2 nanocomposites: New implications for electrochemical hydrogen storage

To meet the demand for sustainable energy development, focusing on storage systems of clean energy like hydrogen is a priority. However, the utilization of new sorbent materials for an in-depth understanding of hydrogen storage mechanisms remains lacking. Herein, a novel composite electrode based on halloysite nanotube-Li0.9Ni0.5Co0.5O2-x/LiFeO2 (HNT-LNCO/LFO) nanostructures with superior electrochemical hydrogen storage behavior is developed via two-pot synthesis strategy, in which the HNT bridges with rich active sites serve as a natural clay support for LNCO/LFO electrocatalysts to equip improved hydrogen sorption kinetics through the spillover phenomena and redox coupling effect. Varied parameters, such as fuel types, the molar ratio of fuel to nitrates, the concentration of the LNCO/LFO (mg/ml), and solvent were optimized to prepare HNT-LNCO/LFO nanocomposites with desired purity, structure, and morphology. These physicochemical changes were realized by a combination of X-ray Powder Diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), High Resolution Transmission Electron Microscopy (HR-TEM), and Brunauer-Emmett-Teller (BET) analyses. Furthermore, the electrochemical nature of the proposed nanocomposites were probed by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronopotentiometry charge–discharge (CCD) process in KOH medium. The effect of conductive LNCO/LFO contents (3.0 %, 5.0 % and 7.0 %) on the HNT substrate was evaluated with the discharge efficiency and hydrogen spillover mechanism. As a consequence, the LNCO/LFO nanoparticles and pristine HNT structures exhibited the hydrogen storage capacities of 499.67 and 84.05 mAhg−1 after 15 cycles, respectively. However, the contribution of LNCO/LFO nanoparticles with weight percent of 3.0 %, 5.0 % and 7.0 % in tubular matrix can produce the discharge efficiencies of 309.33, 437.34 and 132.25 mAhg−1 in three electrode cells, respectively. This systematic work will result in alternative insights of the well-designed HNT-based nanocomposites for highly efficient energy storage applications.

Architectures of flower-like MoS2 nanosheet coated N-doped carbon sphere electrode materials for enhanced capacitive deionization

The development of promising nanomaterials for capacitive deionization (CDI) is an emerging energy-efficient technology for water recovery and purification. Herein, the nanoarchitecture of deposition of molybdenum disulfide nanosheets onto N-doped carbon sphere (MoS2@NCS) has been successfully developed using hydrothermal processes for CDI applications. The morphological and fine structural analyses clearly indicate that the hexagonal structure of MoS2 nanosheets are homogeneously dispersed onto the 300-nm NCS to form the flower-like MoS2@NCS heterostructure. After calcination for 2 h at 800 °C, the MoS2@NCS exhibits a large specific surface area of 82 m2 g−1 and interconnected meso-macroporous channels for rapid ion and electron transfer, resulting in the superior electrochemical behaviors with the specific capacitance of 340 F g−1 at 5 A g−1 in 1 M Na2SO4 solution. Moreover, the electrosorption performance of MoS2@NCS-800 was investigated under different conditions in terms of initial NaCl concentration and voltage, and the superior specific electrosorption capacity of 59.9 mg g−1 is obtained at 2000 mg L−1 NaCl and applied voltage of 1.4 V. The experimental data is then well-fitted with the modified Donnan model, signifying that the electrosorption performance is highly dependent on the formation of electrical double layers and homogeneous potential distribution throughout the diffuse layer of the porous electrodes. The excellent cyclic durability of MoS2@NCS electrode is also highlighted after 100 electrosorption-desorption cycles. These results elaborate that MoS2@NCS composites are promising electrochemical materials for CDI application, which can open a pathway to design the 2D/3D hybrid nanoarchitectures as a highly potential material for green and sustainable water purification and ion removal in grey and salty waters.